[hal,wpilib] Rename FPGA clock to monotonic clock (#8672)

- Remove status return from HAL level (clock getting should never fail)
- Remove 32-bit timestamp expand function
- Make monotonic_clock.hpp (formerly fpga_clock.hpp) header-only and
move to root hal include directory

hal/src/main/java/org/wpilib/hardware/hal/HALUtil.java

@@ -71,11 +71,11 @@ public final class HALUtil extends JNIWrapper {
   public static native int getTeamNumber();
 
   /**
-   * Reads the microsecond-resolution timer on the FPGA.
+   * Reads the microsecond-resolution monotonic timer.
    *
-   * @return The current time in microseconds according to the FPGA (since FPGA reset).
+   * @return The current monotonic time in microseconds.
    */
-  public static native long getFPGATime();
+  public static native long getMonotonicTime();
 
   /**
    * Returns the runtime type of the HAL.

hal/src/main/native/cpp/cpp/fpga_clock.cpp

@@ -1,32 +0,0 @@
-// Copyright (c) FIRST and other WPILib contributors.
-// Open Source Software; you can modify and/or share it under the terms of
-// the WPILib BSD license file in the root directory of this project.
-
-#include "wpi/hal/cpp/fpga_clock.hpp"
-
-#include <cstdio>
-#include <limits>
-
-#include "wpi/hal/HAL.h"
-#include "wpi/util/print.hpp"
-
-namespace wpi::hal {
-const fpga_clock::time_point fpga_clock::min_time =
-    fpga_clock::time_point(fpga_clock::duration(
-        std::numeric_limits<fpga_clock::duration::rep>::min()));
-
-fpga_clock::time_point fpga_clock::now() noexcept {
-  int32_t status = 0;
-  uint64_t currentTime = HAL_GetFPGATime(&status);
-  if (status != 0) {
-    wpi::util::print(
-        stderr,
-        "Call to HAL_GetFPGATime failed in fpga_clock::now() with status {}. "
-        "Initialization might have failed. Time will not be correct\n",
-        status);
-    std::fflush(stderr);
-    return epoch();
-  }
-  return time_point(std::chrono::microseconds(currentTime));
-}
-}  // namespace wpi::hal

hal/src/main/native/cpp/jni/HALUtil.cpp

@@ -473,17 +473,14 @@ Java_org_wpilib_hardware_hal_HALUtil_getTeamNumber
 
 /*
  * Class:     org_wpilib_hardware_hal_HALUtil
- * Method:    getFPGATime
+ * Method:    getMonotonicTime
  * Signature: ()J
  */
 JNIEXPORT jlong JNICALL
-Java_org_wpilib_hardware_hal_HALUtil_getFPGATime
+Java_org_wpilib_hardware_hal_HALUtil_getMonotonicTime
   (JNIEnv* env, jclass)
 {
-  int32_t status = 0;
+  return HAL_GetMonotonicTime();
-  jlong returnValue = HAL_GetFPGATime(&status);
-  CheckStatus(env, status);
-  return returnValue;
 }
 
 /*

hal/src/main/native/include/wpi/hal/HAL.h

@@ -111,29 +111,11 @@ HAL_Bool HAL_GetBrownedOut(int32_t* status);
 int32_t HAL_GetCommsDisableCount(int32_t* status);
 
 /**
- * Reads the microsecond-resolution timer on the FPGA.
+ * Reads the microsecond-resolution monotonic timer.
  *
- * @param[out] status the error code, or 0 for success
+ * @return The current monotonic time in microseconds.
- * @return The current time in microseconds according to the FPGA (since FPGA
- * reset).
  */
-uint64_t HAL_GetFPGATime(int32_t* status);
+uint64_t HAL_GetMonotonicTime(void);
-
-/**
- * Given an 32 bit FPGA time, expand it to the nearest likely 64 bit FPGA time.
- *
- * Note: This is making the assumption that the timestamp being converted is
- * always in the past.  If you call this with a future timestamp, it probably
- * will make it in the past.  If you wait over 70 minutes between capturing the
- * bottom 32 bits of the timestamp and expanding it, you will be off by
- * multiples of 1<<32 microseconds.
- *
- * @param[in] unexpandedLower 32 bit FPGA time
- * @param[out] status the error code, or 0 for success
- * @return The current time in microseconds according to the FPGA (since FPGA
- *         reset) as a 64 bit number.
- */
-uint64_t HAL_ExpandFPGATime(uint32_t unexpandedLower, int32_t* status);
 
 /**
  * Gets the current state of the Robot Signal Light (RSL).

hal/src/main/native/include/wpi/hal/cpp/fpga_clock.hpp

@@ -1,31 +0,0 @@
-// Copyright (c) FIRST and other WPILib contributors.
-// Open Source Software; you can modify and/or share it under the terms of
-// the WPILib BSD license file in the root directory of this project.
-
-#pragma once
-
-#include <chrono>
-
-/** WPILib Hardware Abstraction Layer (HAL) namespace */
-namespace wpi::hal {
-
-/**
- * A std::chrono compatible wrapper around the FPGA Timer.
- */
-class fpga_clock {
- public:
-  using rep = std::chrono::microseconds::rep;
-  using period = std::chrono::microseconds::period;
-  using duration = std::chrono::microseconds;
-  using time_point = std::chrono::time_point<fpga_clock>;
-
-  static fpga_clock::time_point now() noexcept;
-  static constexpr bool is_steady = true;
-
-  static fpga_clock::time_point epoch() noexcept { return time_point(zero()); }
-
-  static fpga_clock::duration zero() noexcept { return duration(0); }
-
-  static const time_point min_time;
-};
-}  // namespace wpi::hal

hal/src/main/native/include/wpi/hal/monotonic_clock.hpp

@@ -0,0 +1,38 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#pragma once
+
+#include <chrono>
+#include <limits>
+
+#include "wpi/hal/HAL.h"
+
+/** WPILib Hardware Abstraction Layer (HAL) namespace */
+namespace wpi::hal {
+
+/**
+ * A std::chrono compatible wrapper around the HAL monotonic timer.
+ */
+class monotonic_clock {
+ public:
+  using rep = std::chrono::microseconds::rep;
+  using period = std::chrono::microseconds::period;
+  using duration = std::chrono::microseconds;
+  using time_point = std::chrono::time_point<monotonic_clock>;
+
+  static time_point now() noexcept {
+    uint64_t currentTime = HAL_GetMonotonicTime();
+    return time_point(std::chrono::microseconds(currentTime));
+  }
+  static constexpr bool is_steady = true;
+
+  static time_point epoch() noexcept { return time_point(zero()); }
+
+  static duration zero() noexcept { return duration(0); }
+
+  static constexpr time_point min_time =
+      time_point(duration(std::numeric_limits<duration::rep>::min()));
+};
+}  // namespace wpi::hal

hal/src/main/native/sim/Alert.cpp

@@ -75,7 +75,7 @@ void HAL_SetAlertActive(HAL_AlertHandle alertHandle, HAL_Bool active,
       // Already active, do nothing (avoids cost of getting time)
       return;
     }
-    int64_t now = HAL_GetFPGATime(status);
+    int64_t now = HAL_GetMonotonicTime();
     int64_t expected = 0;
     // use compare-exchange to avoid potential race
     alert->activeStartTime.compare_exchange_strong(expected, now);

hal/src/main/native/sim/DriverStation.cpp

@@ -20,7 +20,7 @@
 #include "mockdata/DriverStationDataInternal.hpp"
 #include "wpi/hal/DriverStationTypes.h"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 #include "wpi/hal/simulation/MockHooks.h"
 #include "wpi/util/EventVector.hpp"
 #include "wpi/util/mutex.hpp"
@@ -155,16 +155,16 @@ int32_t HAL_SendError(HAL_Bool isError, int32_t errorCode, HAL_Bool isLVCode,
   static constexpr int KEEP_MSGS = 5;
   std::scoped_lock lock(msgMutex);
   static std::string prevMsg[KEEP_MSGS];
-  static fpga_clock::time_point prevMsgTime[KEEP_MSGS];
+  static monotonic_clock::time_point prevMsgTime[KEEP_MSGS];
   static bool initialized = false;
   if (!initialized) {
     for (int i = 0; i < KEEP_MSGS; i++) {
-      prevMsgTime[i] = fpga_clock::now() - std::chrono::seconds(2);
+      prevMsgTime[i] = monotonic_clock::now() - std::chrono::seconds(2);
     }
     initialized = true;
   }
 
-  auto curTime = fpga_clock::now();
+  auto curTime = monotonic_clock::now();
   int i;
   for (i = 0; i < KEEP_MSGS; ++i) {
     if (prevMsg[i] == details) {

hal/src/main/native/sim/HAL.cpp

@@ -254,32 +254,8 @@ int32_t HAL_GetTeamNumber(void) {
   return HALSIM_GetRoboRioTeamNumber();
 }
 
-uint64_t HAL_GetFPGATime(int32_t* status) {
+uint64_t HAL_GetMonotonicTime(void) {
-  return wpi::hal::GetFPGATime();
+  return wpi::hal::GetMonotonicTime();
-}
-
-uint64_t HAL_ExpandFPGATime(uint32_t unexpandedLower, int32_t* status) {
-  // Capture the current FPGA time.  This will give us the upper half of the
-  // clock.
-  uint64_t fpgaTime = HAL_GetFPGATime(status);
-  if (*status != 0) {
-    return 0;
-  }
-
-  // Now, we need to detect the case where the lower bits rolled over after we
-  // sampled.  In that case, the upper bits will be 1 bigger than they should
-  // be.
-
-  // Break it into lower and upper portions.
-  uint32_t lower = fpgaTime & 0xffffffffull;
-  uint64_t upper = (fpgaTime >> 32) & 0xffffffff;
-
-  // The time was sampled *before* the current time, so roll it back.
-  if (lower < unexpandedLower) {
-    --upper;
-  }
-
-  return (upper << 32) + static_cast<uint64_t>(unexpandedLower);
 }
 
 HAL_Bool HAL_GetSystemActive(int32_t* status) {

hal/src/main/native/sim/MockHooks.cpp

@@ -25,7 +25,7 @@ static std::atomic<uint64_t> programStepTime{0};
 
 namespace wpi::hal::init {
 void InitializeMockHooks() {
-  wpi::util::SetNowImpl(GetFPGATime);
+  wpi::util::SetNowImpl(GetMonotonicTime);
 }
 }  // namespace wpi::hal::init
 
@@ -59,7 +59,7 @@ void StepTiming(uint64_t delta) {
   programStepTime += delta;
 }
 
-uint64_t GetFPGATime() {
+uint64_t GetMonotonicTime() {
   uint64_t curTime = programPauseTime;
   if (curTime == 0) {
     curTime = wpi::util::NowDefault();
@@ -67,10 +67,6 @@ uint64_t GetFPGATime() {
   return curTime + programStepTime - programStartTime;
 }
 
-double GetFPGATimestamp() {
-  return GetFPGATime() * 1.0e-6;
-}
-
 void SetProgramStarted(bool started) {
   programStarted = started;
 }
@@ -131,8 +127,7 @@ void HALSIM_StepTiming(uint64_t delta) {
   WaitNotifiers();
 
   while (delta > 0) {
-    int32_t status = 0;
+    uint64_t curTime = HAL_GetMonotonicTime();
-    uint64_t curTime = HAL_GetFPGATime(&status);
     uint64_t nextTimeout = HALSIM_GetNextNotifierTimeout();
     uint64_t step = (std::min)(delta, nextTimeout - curTime);
 

hal/src/main/native/sim/MockHooksInternal.hpp

@@ -17,9 +17,7 @@ bool IsTimingPaused();
 
 void StepTiming(uint64_t delta);
 
-uint64_t GetFPGATime();
+uint64_t GetMonotonicTime();
-
-double GetFPGATimestamp();
 
 void SetProgramStarted();
 }  // namespace wpi::hal

hal/src/main/native/sim/Notifier.cpp

@@ -93,8 +93,7 @@ void NotifierThread::Main() {
 
     // Wait until next alarm
     const Alarm& alarm = m_alarmQueue.top();
-    int32_t status = 0;
+    uint64_t curTime = HAL_GetMonotonicTime();
-    uint64_t curTime = HAL_GetFPGATime(&status);
     if (alarm.notifier->alarmTime > curTime) {
       m_cond.wait_for(
           lock, std::chrono::microseconds{alarm.notifier->alarmTime - curTime});
@@ -114,8 +113,7 @@ void NotifierThread::Main() {
 
 void NotifierThread::ProcessAlarms(
     wpi::util::SmallVectorImpl<HAL_NotifierHandle>* signaled) {
-  int32_t status = 0;
+  uint64_t curTime = HAL_GetMonotonicTime();
-  uint64_t curTime = HAL_GetFPGATime(&status);
 
   // Process alarms
   while (!m_alarmQueue.empty() &&
@@ -264,7 +262,7 @@ void HAL_SetNotifierAlarm(HAL_NotifierHandle notifierHandle, uint64_t alarmTime,
   }
 
   if (!absolute) {
-    alarmTime += HAL_GetFPGATime(status);
+    alarmTime += HAL_GetMonotonicTime();
   }
 
   uint64_t prevWakeup = UINT64_MAX;

hal/src/main/native/systemcore/AddressableLED.cpp

@@ -20,8 +20,8 @@
 #include "SystemServerInternal.hpp"
 #include "wpi/hal/AddressableLEDTypes.h"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
 #include "wpi/hal/handles/HandlesInternal.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 #include "wpi/nt/NetworkTableInstance.hpp"
 #include "wpi/nt/RawTopic.hpp"
 
@@ -133,9 +133,9 @@ void HAL_FreeAddressableLED(HAL_AddressableLEDHandle handle) {
   smartIoHandles->Free(handle, HAL_HandleEnum::AddressableLED);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("AddressableLED handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/Alert.cpp

@@ -75,7 +75,7 @@ void HAL_SetAlertActive(HAL_AlertHandle alertHandle, HAL_Bool active,
       // Already active, do nothing (avoids cost of getting time)
       return;
     }
-    int64_t now = HAL_GetFPGATime(status);
+    int64_t now = HAL_GetMonotonicTime();
     int64_t expected = 0;
     // use compare-exchange to avoid potential race
     alert->activeStartTime.compare_exchange_strong(expected, now);

hal/src/main/native/systemcore/AnalogInput.cpp

@@ -12,8 +12,8 @@
 #include "PortsInternal.hpp"
 #include "SmartIo.hpp"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
 #include "wpi/hal/handles/HandlesInternal.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 
 namespace wpi::hal::init {
 void InitializeAnalogInput() {}
@@ -73,9 +73,9 @@ void HAL_FreeAnalogInputPort(HAL_AnalogInputHandle analogPortHandle) {
   smartIoHandles->Free(analogPortHandle, HAL_HandleEnum::AnalogInput);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("DIO handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/Counter.cpp

@@ -13,7 +13,7 @@
 #include "HALInternal.hpp"
 #include "PortsInternal.hpp"
 #include "SmartIo.hpp"
-#include "wpi/hal/cpp/fpga_clock.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 
 using namespace wpi::hal;
 
@@ -74,9 +74,9 @@ void HAL_FreeCounter(HAL_CounterHandle counterHandle) {
   smartIoHandles->Free(counterHandle, HAL_HandleEnum::Counter);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("DIO handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/DIO.cpp

@@ -13,8 +13,8 @@
 #include "PortsInternal.hpp"
 #include "SmartIo.hpp"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
 #include "wpi/hal/handles/HandlesInternal.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 
 using namespace wpi::hal;
 
@@ -79,9 +79,9 @@ void HAL_FreeDIOPort(HAL_DigitalHandle dioPortHandle) {
   smartIoHandles->Free(dioPortHandle, HAL_HandleEnum::DIO);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("DIO handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/DutyCycle.cpp

@@ -12,8 +12,8 @@
 #include "PortsInternal.hpp"
 #include "SmartIo.hpp"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
 #include "wpi/hal/handles/HandlesInternal.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 
 using namespace wpi::hal;
 
@@ -71,9 +71,9 @@ void HAL_FreeDutyCycle(HAL_DutyCycleHandle dutyCycleHandle) {
   smartIoHandles->Free(dutyCycleHandle, HAL_HandleEnum::DutyCycle);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("DIO handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/HAL.cpp

@@ -205,35 +205,11 @@ int32_t HAL_GetTeamNumber(void) {
   return teamNumber;
 }
 
-uint64_t HAL_GetFPGATime(int32_t* status) {
+uint64_t HAL_GetMonotonicTime(void) {
   wpi::hal::init::CheckInit();
   return wpi::util::NowDefault();
 }
 
-uint64_t HAL_ExpandFPGATime(uint32_t unexpandedLower, int32_t* status) {
-  // Capture the current FPGA time.  This will give us the upper half of the
-  // clock.
-  uint64_t fpgaTime = HAL_GetFPGATime(status);
-  if (*status != 0) {
-    return 0;
-  }
-
-  // Now, we need to detect the case where the lower bits rolled over after we
-  // sampled.  In that case, the upper bits will be 1 bigger than they should
-  // be.
-
-  // Break it into lower and upper portions.
-  uint32_t lower = fpgaTime & 0xffffffffull;
-  uint64_t upper = (fpgaTime >> 32) & 0xffffffff;
-
-  // The time was sampled *before* the current time, so roll it back.
-  if (lower < unexpandedLower) {
-    --upper;
-  }
-
-  return (upper << 32) + static_cast<uint64_t>(unexpandedLower);
-}
-
 HAL_Bool HAL_GetSystemActive(int32_t* status) {
   wpi::hal::init::CheckInit();
   *status = HAL_HANDLE_ERROR;
@@ -296,14 +272,9 @@ HAL_Bool HAL_Initialize(int32_t timeout, int32_t mode) {
 
   // WPILIB_NetworkCommunication_Reserve(nullptr);
 
-  int32_t status = 0;
-
   wpi::hal::InitializeDriverStation();
 
-  dsStartTime = HAL_GetFPGATime(&status);
+  dsStartTime = HAL_GetMonotonicTime();
-  if (status != 0) {
-    return false;
-  }
 
   wpi::hal::WaitForInitialPacket();
 

hal/src/main/native/systemcore/Notifier.cpp

@@ -84,8 +84,7 @@ void NotifierThread::Main() {
 
     // Wait until next alarm
     const Alarm& alarm = m_alarmQueue.top();
-    int32_t status = 0;
+    uint64_t curTime = HAL_GetMonotonicTime();
-    uint64_t curTime = HAL_GetFPGATime(&status);
     if (alarm.notifier->alarmTime > curTime) {
       m_cond.wait_for(
           lock, std::chrono::microseconds{alarm.notifier->alarmTime - curTime});
@@ -99,8 +98,7 @@ void NotifierThread::Main() {
 }
 
 void NotifierThread::ProcessAlarms() {
-  int32_t status = 0;
+  uint64_t curTime = HAL_GetMonotonicTime();
-  uint64_t curTime = HAL_GetFPGATime(&status);
 
   while (!m_alarmQueue.empty() &&
          m_alarmQueue.top().notifier->alarmTime <= curTime) {
@@ -190,7 +188,7 @@ void HAL_SetNotifierAlarm(HAL_NotifierHandle notifierHandle, uint64_t alarmTime,
   }
 
   if (!absolute) {
-    alarmTime += HAL_GetFPGATime(status);
+    alarmTime += HAL_GetMonotonicTime();
   }
 
   uint64_t prevWakeup = UINT64_MAX;

hal/src/main/native/systemcore/PWM.cpp

@@ -15,8 +15,8 @@
 #include "PortsInternal.hpp"
 #include "SmartIo.hpp"
 #include "wpi/hal/Errors.h"
-#include "wpi/hal/cpp/fpga_clock.hpp"
 #include "wpi/hal/handles/HandlesInternal.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 
 using namespace wpi::hal;
 
@@ -83,9 +83,9 @@ void HAL_FreePWMPort(HAL_DigitalHandle pwmPortHandle) {
   smartIoHandles->Free(pwmPortHandle, HAL_HandleEnum::PWM);
 
   // Wait for no other object to hold this handle.
-  auto start = wpi::hal::fpga_clock::now();
+  auto start = wpi::hal::monotonic_clock::now();
   while (port.use_count() != 1) {
-    auto current = wpi::hal::fpga_clock::now();
+    auto current = wpi::hal::monotonic_clock::now();
     if (start + std::chrono::seconds(1) < current) {
       std::puts("PWM handle free timeout");
       std::fflush(stdout);

hal/src/main/native/systemcore/PowerDistribution.cpp

@@ -34,10 +34,7 @@ HAL_PowerDistributionHandle HAL_InitializePowerDistribution(
 
     // Ensure we have been alive for long enough to receive a few Power packets.
     do {
-      uint64_t currentTime = HAL_GetFPGATime(status);
+      uint64_t currentTime = HAL_GetMonotonicTime();
-      if (*status != 0) {
-        return HAL_kInvalidHandle;
-      }
       if (currentTime >= waitTime) {
         break;
       }

hal/src/main/python/semiwrap/HAL.yml

@@ -33,8 +33,7 @@ functions:
   HAL_GetRuntimeType:
   HAL_GetSystemActive:
   HAL_GetBrownedOut:
-  HAL_GetFPGATime:
+  HAL_GetMonotonicTime:
-  HAL_ExpandFPGATime:
   HAL_GetRSLState:
   HAL_GetSystemTimeValid:
   HAL_Initialize:

robotpyExamples/RomiReference/commands/drivetime.py

@@ -30,7 +30,7 @@ class DriveTime(commands2.Command):
 
     def initialize(self) -> None:
         """Called when the command is initially scheduled."""
-        self.startTime = wpilib.Timer.getFPGATimestamp()
+        self.startTime = wpilib.Timer.getTimestamp()
         self.drive.arcadeDrive(0, 0)
 
     def execute(self) -> None:
@@ -43,4 +43,4 @@ class DriveTime(commands2.Command):
 
     def isFinished(self) -> bool:
         """Returns true when the command should end"""
-        return wpilib.Timer.getFPGATimestamp() - self.startTime >= self.duration
+        return wpilib.Timer.getTimestamp() - self.startTime >= self.duration

robotpyExamples/RomiReference/commands/turntime.py

@@ -32,7 +32,7 @@ class TurnTime(commands2.Command):
 
     def initialize(self) -> None:
         """Called when the command is initially scheduled."""
-        self.startTime = wpilib.Timer.getFPGATimestamp()
+        self.startTime = wpilib.Timer.getTimestamp()
         self.drive.arcadeDrive(0, 0)
 
     def execute(self) -> None:
@@ -45,4 +45,4 @@ class TurnTime(commands2.Command):
 
     def isFinished(self) -> bool:
         """Returns true when the command should end"""
-        return wpilib.Timer.getFPGATimestamp() - self.startTime >= self.duration
+        return wpilib.Timer.getTimestamp() - self.startTime >= self.duration

robotpyExamples/XrpReference/commands/drivetime.py

@@ -30,7 +30,7 @@ class DriveTime(commands2.Command):
 
     def initialize(self) -> None:
         """Called when the command is initially scheduled."""
-        self.startTime = wpilib.Timer.getFPGATimestamp()
+        self.startTime = wpilib.Timer.getTimestamp()
         self.drive.arcadeDrive(0, 0)
 
     def execute(self) -> None:
@@ -43,4 +43,4 @@ class DriveTime(commands2.Command):
 
     def isFinished(self) -> bool:
         """Returns true when the command should end"""
-        return wpilib.Timer.getFPGATimestamp() - self.startTime >= self.duration
+        return wpilib.Timer.getTimestamp() - self.startTime >= self.duration

robotpyExamples/XrpReference/commands/turntime.py

@@ -32,7 +32,7 @@ class TurnTime(commands2.Command):
 
     def initialize(self) -> None:
         """Called when the command is initially scheduled."""
-        self.startTime = wpilib.Timer.getFPGATimestamp()
+        self.startTime = wpilib.Timer.getTimestamp()
         self.drive.arcadeDrive(0, 0)
 
     def execute(self) -> None:
@@ -45,4 +45,4 @@ class TurnTime(commands2.Command):
 
     def isFinished(self) -> bool:
         """Returns true when the command should end"""
-        return wpilib.Timer.getFPGATimestamp() - self.startTime >= self.duration
+        return wpilib.Timer.getTimestamp() - self.startTime >= self.duration

simulation/halsim_gui/src/main/native/cpp/DriverStationGui.cpp

@@ -1333,8 +1333,7 @@ void FMSSimModel::Update() {
 
   double matchTime = HALSIM_GetDriverStationMatchTime();
   if (!IsDSDisabled() && enabled) {
-    int32_t status = 0;
+    double curTime = HAL_GetMonotonicTime() * 1.0e-6;
-    double curTime = HAL_GetFPGATime(&status) * 1.0e-6;
     if (m_startMatchTime == -1.0) {
       m_startMatchTime = matchTime + curTime;
     }

simulation/halsim_gui/src/main/native/cpp/TimingGui.cpp

@@ -29,8 +29,7 @@ class TimingModel : public wpi::glass::Model {
 }  // namespace
 
 static void DisplayTiming() {
-  int32_t status = 0;
+  uint64_t curTime = HAL_GetMonotonicTime();
-  uint64_t curTime = HAL_GetFPGATime(&status);
 
   if (ImGui::Button("Run")) {
     HALSIM_ResumeTiming();
@@ -50,7 +49,7 @@ static void DisplayTiming() {
   }
   ImGui::PopButtonRepeat();
   ImGui::PushItemWidth(ImGui::GetFontSize() * 4);
-  ImGui::LabelText("FPGA Time", "%.3f", curTime / 1000000.0);
+  ImGui::LabelText("Time", "%.3f", curTime / 1000000.0);
   ImGui::PopItemWidth();
 
   static std::vector<HALSIM_NotifierInfo> notifiers;

wpilibc/src/main/native/cpp/framework/TimedRobot.cpp

@@ -41,7 +41,7 @@ void TimedRobot::StartCompetition() {
       break;
     }
 
-    m_loopStartTimeUs = RobotController::GetFPGATime();
+    m_loopStartTimeUs = RobotController::GetMonotonicTime();
     std::chrono::microseconds currentTime{m_loopStartTimeUs};
 
     callback.func();
@@ -76,7 +76,7 @@ void TimedRobot::EndCompetition() {
 
 TimedRobot::TimedRobot(wpi::units::second_t period)
     : IterativeRobotBase(period) {
-  m_startTime = std::chrono::microseconds{RobotController::GetFPGATime()};
+  m_startTime = std::chrono::microseconds{RobotController::GetMonotonicTime()};
   AddPeriodic([=, this] { LoopFunc(); }, period);
 
   int32_t status = 0;

wpilibc/src/main/native/cpp/hardware/motor/MotorSafety.cpp

@@ -115,7 +115,7 @@ MotorSafety& MotorSafety::operator=(MotorSafety&& rhs) {
 
 void MotorSafety::Feed() {
   std::scoped_lock lock(m_thisMutex);
-  m_stopTime = Timer::GetFPGATimestamp() + m_expiration;
+  m_stopTime = Timer::GetMonotonicTimestamp() + m_expiration;
 }
 
 void MotorSafety::SetExpiration(wpi::units::second_t expirationTime) {
@@ -130,7 +130,7 @@ wpi::units::second_t MotorSafety::GetExpiration() const {
 
 bool MotorSafety::IsAlive() const {
   std::scoped_lock lock(m_thisMutex);
-  return !m_enabled || m_stopTime > Timer::GetFPGATimestamp();
+  return !m_enabled || m_stopTime > Timer::GetMonotonicTimestamp();
 }
 
 void MotorSafety::SetSafetyEnabled(bool enabled) {
@@ -157,7 +157,7 @@ void MotorSafety::Check() {
     return;
   }
 
-  if (stopTime < Timer::GetFPGATimestamp()) {
+  if (stopTime < Timer::GetMonotonicTimestamp()) {
     WPILIB_ReportError(
         err::Timeout,
         "{}... Output not updated often enough. See "

wpilibc/src/main/native/cpp/opmode/PeriodicOpMode.cpp

@@ -25,7 +25,7 @@ PeriodicOpMode::Callback::Callback(std::function<void()> func,
       period{period},
       expirationTime(
           startTime + offset + period +
-          (std::chrono::microseconds{wpi::RobotController::GetFPGATime()} -
+          (std::chrono::microseconds{wpi::RobotController::GetMonotonicTime()} -
            startTime) /
               period * period) {}
 
@@ -38,7 +38,7 @@ PeriodicOpMode::~PeriodicOpMode() {
 PeriodicOpMode::PeriodicOpMode(wpi::units::second_t period)
     : m_period{period},
       m_watchdog(period, [this] { PrintLoopOverrunMessage(); }) {
-  m_startTime = std::chrono::microseconds{RobotController::GetFPGATime()};
+  m_startTime = std::chrono::microseconds{RobotController::GetMonotonicTime()};
   AddPeriodic([=, this] { LoopFunc(); }, period);
 
   int32_t status = 0;
@@ -116,7 +116,7 @@ void PeriodicOpMode::OpModeRun(int64_t opModeId) {
       break;
     }
 
-    m_loopStartTimeUs = RobotController::GetFPGATime();
+    m_loopStartTimeUs = RobotController::GetMonotonicTime();
     std::chrono::microseconds currentTime{m_loopStartTimeUs};
 
     callback.func();

wpilibc/src/main/native/cpp/system/RobotController.cpp

@@ -16,7 +16,7 @@
 using namespace wpi;
 
 std::function<uint64_t()> RobotController::m_timeSource = [] {
-  return RobotController::GetFPGATime();
+  return RobotController::GetMonotonicTime();
 };
 
 std::string RobotController::GetSerialNumber() {
@@ -47,11 +47,8 @@ uint64_t RobotController::GetTime() {
   return m_timeSource();
 }
 
-uint64_t RobotController::GetFPGATime() {
+uint64_t RobotController::GetMonotonicTime() {
-  int32_t status = 0;
+  return HAL_GetMonotonicTime();
-  uint64_t time = HAL_GetFPGATime(&status);
-  WPILIB_CheckErrorStatus(status, "GetFPGATime");
-  return time;
 }
 
 wpi::units::volt_t RobotController::GetBatteryVoltage() {

wpilibc/src/main/native/cpp/system/Timer.cpp

@@ -16,7 +16,7 @@ void Wait(wpi::units::second_t seconds) {
   std::this_thread::sleep_for(std::chrono::duration<double>(seconds.value()));
 }
 
-wpi::units::second_t GetTime() {
+wpi::units::second_t GetSystemTime() {
   using std::chrono::duration;
   using std::chrono::duration_cast;
   using std::chrono::system_clock;
@@ -92,9 +92,10 @@ wpi::units::second_t Timer::GetTimestamp() {
   return wpi::units::second_t{wpi::RobotController::GetTime() * 1.0e-6};
 }
 
-wpi::units::second_t Timer::GetFPGATimestamp() {
+wpi::units::second_t Timer::GetMonotonicTimestamp() {
-  // FPGA returns the timestamp in microseconds
+  // Monotonic timestamp is in microseconds
-  return wpi::units::second_t{wpi::RobotController::GetFPGATime() * 1.0e-6};
+  return wpi::units::second_t{wpi::RobotController::GetMonotonicTime() *
+                              1.0e-6};
 }
 
 wpi::units::second_t Timer::GetMatchTime() {

wpilibc/src/main/native/cpp/system/Tracer.cpp

@@ -17,7 +17,7 @@ Tracer::Tracer() {
 }
 
 void Tracer::ResetTimer() {
-  m_startTime = wpi::hal::fpga_clock::now();
+  m_startTime = wpi::hal::monotonic_clock::now();
 }
 
 void Tracer::ClearEpochs() {
@@ -26,7 +26,7 @@ void Tracer::ClearEpochs() {
 }
 
 void Tracer::AddEpoch(std::string_view epochName) {
-  auto currentTime = wpi::hal::fpga_clock::now();
+  auto currentTime = wpi::hal::monotonic_clock::now();
   m_epochs[epochName] = currentTime - m_startTime;
   m_startTime = currentTime;
 }
@@ -44,7 +44,7 @@ void Tracer::PrintEpochs(wpi::util::raw_ostream& os) {
   using std::chrono::duration_cast;
   using std::chrono::microseconds;
 
-  auto now = wpi::hal::fpga_clock::now();
+  auto now = wpi::hal::monotonic_clock::now();
   if (now - m_lastEpochsPrintTime > kMinPrintPeriod) {
     m_lastEpochsPrintTime = now;
     for (const auto& epoch : m_epochs) {

wpilibc/src/main/native/cpp/system/Watchdog.cpp

@@ -87,7 +87,6 @@ void Watchdog::Impl::UpdateAlarm() {
 
 void Watchdog::Impl::Main() {
   for (;;) {
-    int32_t status = 0;
     HAL_NotifierHandle notifier = m_notifier.load();
     if (notifier == 0) {
       break;
@@ -95,7 +94,7 @@ void Watchdog::Impl::Main() {
     if (WPI_WaitForObject(notifier) == 0) {
       break;
     }
-    uint64_t curTime = HAL_GetFPGATime(&status);
+    uint64_t curTime = HAL_GetMonotonicTime();
 
     std::unique_lock lock(m_mutex);
 
@@ -163,11 +162,11 @@ Watchdog& Watchdog::operator=(Watchdog&& rhs) {
 }
 
 wpi::units::second_t Watchdog::GetTime() const {
-  return Timer::GetFPGATimestamp() - m_startTime;
+  return Timer::GetMonotonicTimestamp() - m_startTime;
 }
 
 void Watchdog::SetTimeout(wpi::units::second_t timeout) {
-  m_startTime = Timer::GetFPGATimestamp();
+  m_startTime = Timer::GetMonotonicTimestamp();
   m_tracer.ClearEpochs();
 
   std::scoped_lock lock(m_impl->m_mutex);
@@ -203,7 +202,7 @@ void Watchdog::Reset() {
 }
 
 void Watchdog::Enable() {
-  m_startTime = Timer::GetFPGATimestamp();
+  m_startTime = Timer::GetMonotonicTimestamp();
   m_tracer.ClearEpochs();
 
   std::scoped_lock lock(m_impl->m_mutex);

wpilibc/src/main/native/include/wpi/framework/TimedRobot.hpp

@@ -64,9 +64,10 @@ class TimedRobot : public IterativeRobotBase {
 
   /**
    * Return the system clock time in microseconds for the start of the current
-   * periodic loop. This is in the same time base as Timer.GetFPGATimestamp(),
+   * periodic loop. This is in the same time base as
-   * but is stable through a loop. It is updated at the beginning of every
+   * Timer.GetMonotonicTimestamp(), but is stable through a loop. It is updated
-   * periodic callback (including the normal periodic loop).
+   * at the beginning of every periodic callback (including the normal periodic
+   * loop).
    *
    * @return Robot running time in microseconds, as of the start of the current
    * periodic function.
@@ -107,11 +108,11 @@ class TimedRobot : public IterativeRobotBase {
              std::chrono::microseconds period, std::chrono::microseconds offset)
         : func{std::move(func)},
           period{period},
-          expirationTime(
+          expirationTime(startTime + offset + period +
-              startTime + offset + period +
+                         (std::chrono::microseconds{
-              (std::chrono::microseconds{wpi::RobotController::GetFPGATime()} -
+                              wpi::RobotController::GetMonotonicTime()} -
-               startTime) /
+                          startTime) /
-                  period * period) {}
+                             period * period) {}
 
     bool operator>(const Callback& rhs) const {
       return expirationTime > rhs.expirationTime;

wpilibc/src/main/native/include/wpi/hardware/motor/MotorSafety.hpp

@@ -114,7 +114,7 @@ class MotorSafety {
   bool m_enabled = false;
 
   // The FPGA clock value when the motor has expired
-  wpi::units::second_t m_stopTime = Timer::GetFPGATimestamp();
+  wpi::units::second_t m_stopTime = Timer::GetMonotonicTimestamp();
 
   mutable wpi::util::mutex m_thisMutex;
 };

wpilibc/src/main/native/include/wpi/opmode/PeriodicOpMode.hpp

@@ -91,9 +91,10 @@ class PeriodicOpMode : public OpMode {
 
   /**
    * Return the system clock time in microseconds for the start of the current
-   * periodic loop. This is in the same time base as Timer.getFPGATimestamp(),
+   * periodic loop. This is in the same time base as
-   * but is stable through a loop. It is updated at the beginning of every
+   * Timer::GetMonotonicTimestamp(), but is stable through a loop. It is updated
-   * periodic callback (including the normal periodic loop).
+   * at the beginning of every periodic callback (including the normal periodic
+   * loop).
    *
    * @return Robot running time in microseconds, as of the start of the current
    * periodic function.

wpilibc/src/main/native/include/wpi/system/RobotController.hpp

@@ -60,22 +60,21 @@ class RobotController {
   static void SetTimeSource(std::function<uint64_t()> supplier);
 
   /**
-   * Read the microsecond timestamp. By default, the time is based on the FPGA
+   * Read the microsecond timestamp. By default, the time is based on the
-   * hardware clock in microseconds since the FPGA started. However, the return
+   * monotonic clock. However, the return value of this method may be modified
-   * value of this method may be modified to use any time base, including
+   * to use any time base, including non-monotonic and non-continuous time
-   * non-monotonic and non-continuous time bases.
+   * bases.
    *
    * @return The current time in microseconds.
    */
   static uint64_t GetTime();
 
   /**
-   * Read the microsecond-resolution timer on the FPGA.
+   * Read the microsecond-resolution monotonic timer.
    *
-   * @return The current time in microseconds according to the FPGA (since FPGA
+   * @return The current monotonic time in microseconds.
-   *         reset).
    */
-  static uint64_t GetFPGATime();
+  static uint64_t GetMonotonicTime();
 
   /**
    * Read the battery voltage.

wpilibc/src/main/native/include/wpi/system/Timer.hpp

@@ -25,7 +25,7 @@ void Wait(wpi::units::second_t seconds);
  * @return The time, just in case you want the robot to start autonomous at 8pm
  *         on Saturday.
  */
-wpi::units::second_t GetTime();
+wpi::units::second_t GetSystemTime();
 
 /**
  * A timer class.
@@ -119,24 +119,22 @@ class Timer {
   bool IsRunning() const;
 
   /**
-   * Return the clock time in seconds. By default, the time is based on the FPGA
+   * Return the clock time in seconds. By default, the time is the time returned
-   * hardware clock in seconds since the FPGA started. However, the return value
+   * by GetMonotonicTimestamp(). However, the return value of this method may be
-   * of this method may be modified to use any time base, including
+   * modified to use any time base, including non-monotonic time bases.
-   * non-monotonic time bases.
    *
    * @returns Robot running time in seconds.
    */
   static wpi::units::second_t GetTimestamp();
 
   /**
-   * Return the FPGA system clock time in seconds.
+   * Return the monotonic clock time in seconds.
    *
-   * Return the time from the FPGA hardware clock in seconds since the FPGA
+   * Return the time from the monotonic clock in seconds.
-   * started. Rolls over after 71 minutes.
    *
-   * @returns Robot running time in seconds.
+   * @returns Monotonic time in seconds.
    */
-  static wpi::units::second_t GetFPGATimestamp();
+  static wpi::units::second_t GetMonotonicTimestamp();
 
   /**
    * Return the approximate match time. The FMS does not send an official match

wpilibc/src/main/native/include/wpi/system/Tracer.hpp

@@ -7,7 +7,7 @@
 #include <chrono>
 #include <string_view>
 
-#include "wpi/hal/cpp/fpga_clock.hpp"
+#include "wpi/hal/monotonic_clock.hpp"
 #include "wpi/util/StringMap.hpp"
 
 namespace wpi::util {
@@ -65,9 +65,9 @@ class Tracer {
  private:
   static constexpr std::chrono::milliseconds kMinPrintPeriod{1000};
 
-  wpi::hal::fpga_clock::time_point m_startTime;
+  wpi::hal::monotonic_clock::time_point m_startTime;
-  wpi::hal::fpga_clock::time_point m_lastEpochsPrintTime =
+  wpi::hal::monotonic_clock::time_point m_lastEpochsPrintTime =
-      wpi::hal::fpga_clock::epoch();
+      wpi::hal::monotonic_clock::epoch();
 
   wpi::util::StringMap<std::chrono::nanoseconds> m_epochs;
 };

wpilibc/src/main/python/semiwrap/RobotController.yml

@@ -14,7 +14,7 @@ classes:
       GetTeamNumber:
       SetTimeSource:
       GetTime:
-      GetFPGATime:
+      GetMonotonicTime:
       IsSysActive:
       IsBrownedOut:
       GetRSLState:

wpilibc/src/main/python/semiwrap/Timer.yml

@@ -1,6 +1,6 @@
 functions:
   Wait:
-  GetTime:
+  GetSystemTime:
 classes:
   wpi::Timer:
     methods:
@@ -10,7 +10,7 @@ classes:
       Start:
       Restart:
       Stop:
-      GetFPGATimestamp:
+      GetMonotonicTimestamp:
       GetMatchTime:
       HasElapsed:
       AdvanceIfElapsed:

wpilibc/src/main/python/wpilib/__init__.py

@@ -99,7 +99,7 @@ from ._wpilib import (
     getDeployDirectory,
     getErrorMessage,
     getOperatingDirectory,
-    getTime,
+    getSystemTime,
     setCurrentThreadPriority,
     wait,
 )
@@ -202,7 +202,7 @@ __all__ = [
     "getDeployDirectory",
     "getErrorMessage",
     "getOperatingDirectory",
-    "getTime",
+    "getSystemTime",
     "setCurrentThreadPriority",
     "wait",
 ]

wpilibc/src/test/native/cpp/TimerTest.cpp

@@ -112,9 +112,9 @@ TEST_F(TimerTest, AdvanceIfElapsed) {
   EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
 }
 
-TEST_F(TimerTest, GetFPGATimestamp) {
+TEST_F(TimerTest, GetMonotonicTimestamp) {
-  auto start = wpi::Timer::GetFPGATimestamp();
+  auto start = wpi::Timer::GetMonotonicTimestamp();
   wpi::sim::StepTiming(500_ms);
-  auto end = wpi::Timer::GetFPGATimestamp();
+  auto end = wpi::Timer::GetMonotonicTimestamp();
   EXPECT_EQ(start + 500_ms, end);
 }

wpilibj/src/main/java/org/wpilib/framework/TimedRobot.java

@@ -44,7 +44,7 @@ public class TimedRobot extends IterativeRobotBase {
           startTime
               + offset
               + this.period
-              + (RobotController.getFPGATime() - startTime) / this.period * this.period;
+              + (RobotController.getMonotonicTime() - startTime) / this.period * this.period;
     }
 
     @Override
@@ -89,7 +89,7 @@ public class TimedRobot extends IterativeRobotBase {
    */
   protected TimedRobot(double period) {
     super(period);
-    m_startTimeUs = RobotController.getFPGATime();
+    m_startTimeUs = RobotController.getMonotonicTime();
     addPeriodic(this::loopFunc, period);
     NotifierJNI.setNotifierName(m_notifier, "TimedRobot");
 
@@ -146,7 +146,7 @@ public class TimedRobot extends IterativeRobotBase {
         break;
       }
 
-      long currentTime = RobotController.getFPGATime();
+      long currentTime = RobotController.getMonotonicTime();
       m_loopStartTimeUs = currentTime;
 
       callback.func.run();
@@ -182,7 +182,7 @@ public class TimedRobot extends IterativeRobotBase {
 
   /**
    * Return the system clock time in microseconds for the start of the current periodic loop. This
-   * is in the same time base as Timer.getFPGATimestamp(), but is stable through a loop. It is
+   * is in the same time base as Timer.getMonotonicTimestamp(), but is stable through a loop. It is
    * updated at the beginning of every periodic callback (including the normal periodic loop).
    *
    * @return Robot running time in microseconds, as of the start of the current periodic function.

wpilibj/src/main/java/org/wpilib/hardware/motor/MotorSafety.java

@@ -25,7 +25,7 @@ public abstract class MotorSafety {
 
   private double m_expiration = kDefaultSafetyExpiration;
   private boolean m_enabled;
-  private double m_stopTime = Timer.getFPGATimestamp();
+  private double m_stopTime = Timer.getMonotonicTimestamp();
   private final Object m_thisMutex = new Object();
   private static final Set<MotorSafety> m_instanceList = new LinkedHashSet<>();
   private static final Object m_listMutex = new Object();
@@ -83,7 +83,7 @@ public abstract class MotorSafety {
    */
   public void feed() {
     synchronized (m_thisMutex) {
-      m_stopTime = Timer.getFPGATimestamp() + m_expiration;
+      m_stopTime = Timer.getMonotonicTimestamp() + m_expiration;
     }
   }
 
@@ -116,7 +116,7 @@ public abstract class MotorSafety {
    */
   public boolean isAlive() {
     synchronized (m_thisMutex) {
-      return !m_enabled || m_stopTime > Timer.getFPGATimestamp();
+      return !m_enabled || m_stopTime > Timer.getMonotonicTimestamp();
     }
   }
 
@@ -138,7 +138,7 @@ public abstract class MotorSafety {
       return;
     }
 
-    if (stopTime < Timer.getFPGATimestamp()) {
+    if (stopTime < Timer.getMonotonicTimestamp()) {
       DriverStation.reportError(
           getDescription()
               + "... Output not updated often enough. See https://docs.wpilib.org/motorsafety for more information.",

wpilibj/src/main/java/org/wpilib/opmode/PeriodicOpMode.java

@@ -66,7 +66,7 @@ public abstract class PeriodicOpMode implements OpMode {
           startTime
               + offset
               + this.period
-              + (RobotController.getFPGATime() - startTime) / this.period * this.period;
+              + (RobotController.getMonotonicTime() - startTime) / this.period * this.period;
     }
 
     @Override
@@ -120,7 +120,7 @@ public abstract class PeriodicOpMode implements OpMode {
    * @param period period (in seconds) for callbacks to the periodic() function
    */
   protected PeriodicOpMode(double period) {
-    m_startTimeUs = RobotController.getFPGATime();
+    m_startTimeUs = RobotController.getMonotonicTime();
     m_period = period;
     m_watchdog = new Watchdog(period, this::printLoopOverrunMessage);
 
@@ -157,8 +157,8 @@ public abstract class PeriodicOpMode implements OpMode {
 
   /**
    * Return the system clock time in micrseconds for the start of the current periodic loop. This is
-   * in the same time base as Timer.getFPGATimestamp(), but is stable through a loop. It is updated
+   * in the same time base as Timer.getMonotonicTimestamp(), but is stable through a loop. It is
-   * at the beginning of every periodic callback (including the normal periodic loop).
+   * updated at the beginning of every periodic callback (including the normal periodic loop).
    *
    * @return Robot running time in microseconds, as of the start of the current periodic function.
    */
@@ -290,8 +290,8 @@ public abstract class PeriodicOpMode implements OpMode {
         break;
       }
 
-      long currentTime = RobotController.getFPGATime();
+      long currentTime = RobotController.getMonotonicTime();
-      m_loopStartTimeUs = RobotController.getFPGATime();
+      m_loopStartTimeUs = RobotController.getMonotonicTime();
 
       callback.func.run();
 

wpilibj/src/main/java/org/wpilib/system/RobotController.java

@@ -22,7 +22,7 @@ import org.wpilib.units.measure.Voltage;
 
 /** Contains functions for roboRIO functionality. */
 public final class RobotController {
-  private static LongSupplier m_timeSource = RobotController::getFPGATime;
+  private static LongSupplier m_timeSource = RobotController::getMonotonicTime;
 
   private RobotController() {
     throw new UnsupportedOperationException("This is a utility class!");
@@ -69,9 +69,9 @@ public final class RobotController {
   }
 
   /**
-   * Read the microsecond timestamp. By default, the time is based on the FPGA hardware clock in
+   * Read the microsecond timestamp. By default, the time is based on the monotonic clock. However,
-   * microseconds since the FPGA started. However, the return value of this method may be modified
+   * the return value of this method may be modified to use any time base, including non-monotonic
-   * to use any time base, including non-monotonic and non-continuous time bases.
+   * and non-continuous time bases.
    *
    * @return The current time in microseconds.
    */
@@ -80,9 +80,9 @@ public final class RobotController {
   }
 
   /**
-   * Read the microsecond timestamp. By default, the time is based on the FPGA hardware clock in
+   * Read the microsecond timestamp. By default, the time is based on the monotonic clock. However,
-   * microseconds since the FPGA started. However, the return value of this method may be modified
+   * the return value of this method may be modified to use any time base, including non-monotonic
-   * to use any time base, including non-monotonic and non-continuous time bases.
+   * and non-continuous time bases.
    *
    * @return The current time in a measure.
    */
@@ -91,21 +91,21 @@ public final class RobotController {
   }
 
   /**
-   * Read the microsecond timer from the FPGA.
+   * Read the microsecond monotonic timer.
    *
-   * @return The current time in microseconds according to the FPGA.
+   * @return The current monotonic time in microseconds.
    */
-  public static long getFPGATime() {
+  public static long getMonotonicTime() {
-    return HALUtil.getFPGATime();
+    return HALUtil.getMonotonicTime();
   }
 
   /**
-   * Read the microsecond timer in a measure from the FPGA.
+   * Read the microsecond monotonic timer in a measure.
    *
-   * @return The current time according to the FPGA in a measure.
+   * @return The current monotonic time in a measure.
    */
-  public static Time getMeasureFPGATime() {
+  public static Time getMeasureMonotonicTime() {
-    return Microseconds.of(HALUtil.getFPGATime());
+    return Microseconds.of(HALUtil.getMonotonicTime());
   }
 
   /**

wpilibj/src/main/java/org/wpilib/system/Timer.java

@@ -17,9 +17,9 @@ import org.wpilib.units.measure.Time;
  */
 public class Timer {
   /**
-   * Return the clock time in seconds. By default, the time is based on the FPGA hardware clock in
+   * Return the clock time in seconds. By default, the time is the time returned by
-   * seconds since the FPGA started. However, the return value of this method may be modified to use
+   * getMonotonicTimestamp(). However, the return value of this method may be modified to use any
-   * any time base, including non-monotonic time bases.
+   * time base, including non-monotonic time bases.
    *
    * @return Robot running time in seconds.
    */
@@ -28,13 +28,12 @@ public class Timer {
   }
 
   /**
-   * Return the system clock time in seconds. Return the time from the FPGA hardware clock in
+   * Return the monotonic clock time in seconds.
-   * seconds since the FPGA started.
    *
-   * @return Robot running time in seconds.
+   * @return Monotonic time in seconds.
    */
-  public static double getFPGATimestamp() {
+  public static double getMonotonicTimestamp() {
-    return RobotController.getFPGATime() / 1000000.0;
+    return RobotController.getMonotonicTime() / 1000000.0;
   }
 
   /**

wpilibj/src/main/java/org/wpilib/system/Tracer.java

@@ -38,7 +38,7 @@ public class Tracer {
 
   /** Restarts the epoch timer. */
   public final void resetTimer() {
-    m_startTime = RobotController.getFPGATime();
+    m_startTime = RobotController.getMonotonicTime();
   }
 
   /**
@@ -53,7 +53,7 @@ public class Tracer {
    * @param epochName The name to associate with the epoch.
    */
   public void addEpoch(String epochName) {
-    long currentTime = RobotController.getFPGATime();
+    long currentTime = RobotController.getMonotonicTime();
     m_epochs.put(epochName, currentTime - m_startTime);
     m_startTime = currentTime;
   }
@@ -71,7 +71,7 @@ public class Tracer {
    * @param output the stream that the output is sent to
    */
   public void printEpochs(Consumer<String> output) {
-    long now = RobotController.getFPGATime();
+    long now = RobotController.getMonotonicTime();
     if (now - m_lastEpochsPrintTime > kMinPrintPeriod) {
       StringBuilder sb = new StringBuilder();
       m_lastEpochsPrintTime = now;

wpilibj/src/main/java/org/wpilib/system/Watchdog.java

@@ -100,7 +100,7 @@ public class Watchdog implements Closeable, Comparable<Watchdog> {
    * @return The time in seconds since the watchdog was last fed.
    */
   public double getTime() {
-    return Timer.getFPGATimestamp() - m_startTime;
+    return Timer.getMonotonicTimestamp() - m_startTime;
   }
 
   /**
@@ -109,7 +109,7 @@ public class Watchdog implements Closeable, Comparable<Watchdog> {
    * @param timeout The watchdog's timeout in seconds with microsecond resolution.
    */
   public void setTimeout(double timeout) {
-    m_startTime = Timer.getFPGATimestamp();
+    m_startTime = Timer.getMonotonicTimestamp();
     m_tracer.clearEpochs();
 
     m_queueMutex.lock();
@@ -184,7 +184,7 @@ public class Watchdog implements Closeable, Comparable<Watchdog> {
 
   /** Enables the watchdog timer. */
   public void enable() {
-    m_startTime = Timer.getFPGATimestamp();
+    m_startTime = Timer.getMonotonicTimestamp();
     m_tracer.clearEpochs();
 
     m_queueMutex.lock();
@@ -247,7 +247,7 @@ public class Watchdog implements Closeable, Comparable<Watchdog> {
         Thread.currentThread().interrupt();
         break;
       }
-      long curTime = HALUtil.getFPGATime();
+      long curTime = HALUtil.getMonotonicTime();
 
       m_queueMutex.lock();
       try {

wpilibj/src/test/java/org/wpilib/hardware/led/LEDPatternTest.java

@@ -69,7 +69,7 @@ class LEDPatternTest {
 
   @AfterEach
   void tearDown() {
-    RobotController.setTimeSource(RobotController::getFPGATime);
+    RobotController.setTimeSource(RobotController::getMonotonicTime);
   }
 
   @Test

wpilibj/src/test/java/org/wpilib/system/TimerTest.java

@@ -127,10 +127,10 @@ class TimerTest {
 
   @Test
   @ResourceLock("timing")
-  void getFPGATimestampTest() {
+  void getMonotonicTimestampTest() {
-    double start = Timer.getFPGATimestamp();
+    double start = Timer.getMonotonicTimestamp();
     SimHooks.stepTiming(0.5);
-    double end = Timer.getFPGATimestamp();
+    double end = Timer.getMonotonicTimestamp();
     assertEquals(start + 0.5, end, 1e-9);
   }
 }

wpimath/src/main/java/org/wpilib/math/estimator/PoseEstimator.java

@@ -272,9 +272,9 @@ public class PoseEstimator<T> {
    * @param timestamp The timestamp of the vision measurement in seconds. Note that if you don't use
    *     your own time source by calling {@link
    *     PoseEstimator#updateWithTime(double,Rotation2d,Object)} then you must use a timestamp with
-   *     an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as {@link
+   *     the same epoch as {@link org.wpilib.system.Timer#getMonotonicTimestamp()}.) This means that
-   *     org.wpilib.system.Timer#getFPGATimestamp()}.) This means that you should use {@link
+   *     you should use {@link org.wpilib.system.Timer#getMonotonicTimestamp()} as your time source
-   *     org.wpilib.system.Timer#getFPGATimestamp()} as your time source or sync the epochs.
+   *     or sync the epochs.
    */
   public void addVisionMeasurement(Pose2d visionRobotPose, double timestamp) {
     // Step 0: If this measurement is old enough to be outside the pose buffer's timespan, skip.
@@ -344,9 +344,9 @@ public class PoseEstimator<T> {
    * @param visionRobotPose The pose of the robot as measured by the vision camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note that if you don't use
    *     your own time source by calling {@link #updateWithTime}, then you must use a timestamp with
-   *     an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as {@link
+   *     the same epoch as {@link org.wpilib.system.Timer#getMonotonicTimestamp()}). This means that
-   *     org.wpilib.system.Timer#getFPGATimestamp()}). This means that you should use {@link
+   *     you should use {@link org.wpilib.system.Timer#getMonotonicTimestamp()} as your time source
-   *     org.wpilib.system.Timer#getFPGATimestamp()} as your time source in this case.
+   *     in this case.
    * @param visionMeasurementStdDevs Standard deviations of the vision pose measurement (x position
    *     in meters, y position in meters, and heading in radians). Increase these numbers to trust
    *     the vision pose measurement less.

wpimath/src/main/java/org/wpilib/math/estimator/PoseEstimator3d.java

@@ -283,9 +283,9 @@ public class PoseEstimator3d<T> {
    * @param timestamp The timestamp of the vision measurement in seconds. Note that if you don't use
    *     your own time source by calling {@link
    *     PoseEstimator3d#updateWithTime(double,Rotation3d,Object)} then you must use a timestamp
-   *     with an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as
+   *     with the same epoch as {@link org.wpilib.system.Timer#getMonotonicTimestamp()}.) This means
-   *     {@link org.wpilib.system.Timer#getFPGATimestamp()}.) This means that you should use {@link
+   *     that you should use {@link org.wpilib.system.Timer#getMonotonicTimestamp()} as your time
-   *     org.wpilib.system.Timer#getFPGATimestamp()} as your time source or sync the epochs.
+   *     source or sync the epochs.
    */
   public void addVisionMeasurement(Pose3d visionRobotPose, double timestamp) {
     // Step 0: If this measurement is old enough to be outside the pose buffer's timespan, skip.
@@ -359,9 +359,9 @@ public class PoseEstimator3d<T> {
    * @param visionRobotPose The pose of the robot as measured by the vision camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note that if you don't use
    *     your own time source by calling {@link #updateWithTime}, then you must use a timestamp with
-   *     an epoch since FPGA startup (i.e., the epoch of this timestamp is the same epoch as {@link
+   *     the same epoch as {@link org.wpilib.system.Timer#getMonotonicTimestamp()}). This means that
-   *     org.wpilib.system.Timer#getFPGATimestamp()}). This means that you should use {@link
+   *     you should use {@link org.wpilib.system.Timer#getMonotonicTimestamp()} as your time source
-   *     org.wpilib.system.Timer#getFPGATimestamp()} as your time source in this case.
+   *     in this case.
    * @param visionMeasurementStdDevs Standard deviations of the vision pose measurement (x position
    *     in meters, y position in meters, z position in meters, and angle in radians). Increase
    *     these numbers to trust the vision pose measurement less.

wpimath/src/main/native/include/wpi/math/estimator/PoseEstimator.hpp

@@ -280,10 +280,9 @@ class WPILIB_DLLEXPORT PoseEstimator {
    *     camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note
    *     that if you don't use your own time source by calling UpdateWithTime(),
-   *     then you must use a timestamp with an epoch since FPGA startup (i.e.,
+   *     then you must use a timestamp with the same epoch as
-   *     the epoch of this timestamp is the same epoch as
+   *     wpi::Timer::GetMonotonicTimestamp(). This means that you should use
-   *     wpi::math::Timer::GetTimestamp(). This means that you should use
+   *     wpi::Timer::GetMonotonicTimestamp() as your time source in this case.
-   *     wpi::math::Timer::GetTimestamp() as your time source in this case.
    */
   void AddVisionMeasurement(const Pose2d& visionRobotPose,
                             wpi::units::second_t timestamp) {
@@ -365,10 +364,9 @@ class WPILIB_DLLEXPORT PoseEstimator {
    *     camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note
    *     that if you don't use your own time source by calling UpdateWithTime(),
-   *     then you must use a timestamp with an epoch since FPGA startup (i.e.,
+   *     then you must use a timestamp with the same epoch as
-   *     the epoch of this timestamp is the same epoch as
+   *     wpi::Timer::GetMonotonicTimestamp(). This means that you should use
-   *     wpi::math::Timer::GetTimestamp(). This means that you should use
+   *     wpi::Timer::GetMonotonicTimestamp() as your time source in this case.
-   *     wpi::math::Timer::GetTimestamp() as your time source in this case.
    * @param visionMeasurementStdDevs Standard deviations of the vision pose
    *     measurement (x position in meters, y position in meters, and heading in
    *     radians). Increase these numbers to trust the vision pose measurement

wpimath/src/main/native/include/wpi/math/estimator/PoseEstimator3d.hpp

@@ -288,10 +288,9 @@ class WPILIB_DLLEXPORT PoseEstimator3d {
    *     camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note
    *     that if you don't use your own time source by calling UpdateWithTime(),
-   *     then you must use a timestamp with an epoch since FPGA startup (i.e.,
+   *     then you must use a timestamp with the same epoch as
-   *     the epoch of this timestamp is the same epoch as
+   *     wpi::Timer::GetMonotonicTimestamp(). This means that you should use
-   *     wpi::math::Timer::GetFPGATimestamp(). This means that you should use
+   *     wpi::Timer::GetMonotonicTimestamp() as your time source in this case.
-   *     wpi::math::Timer::GetFPGATimestamp() as your time source in this case.
    */
   void AddVisionMeasurement(const Pose3d& visionRobotPose,
                             wpi::units::second_t timestamp) {
@@ -379,10 +378,9 @@ class WPILIB_DLLEXPORT PoseEstimator3d {
    *     camera.
    * @param timestamp The timestamp of the vision measurement in seconds. Note
    *     that if you don't use your own time source by calling UpdateWithTime(),
-   *     then you must use a timestamp with an epoch since FPGA startup (i.e.,
+   *     then you must use a timestamp with the same epoch as
-   *     the epoch of this timestamp is the same epoch as
+   *     wpi::Timer::GetMonotonicTimestamp(). This means that you should use
-   *     wpi::math::Timer::GetFPGATimestamp(). This means that you should use
+   *     wpi::Timer::GetMonotonicTimestamp() as your time source in this case.
-   *     wpi::math::Timer::GetFPGATimestamp() as your time source in this case.
    * @param visionMeasurementStdDevs Standard deviations of the vision pose
    *     measurement (x position in meters, y position in meters, and heading in
    *     radians). Increase these numbers to trust the vision pose measurement