Add examples for DMA, DutyCycle, DutyCycleEncoder and AddressableLED (#2100)

wpilibcExamples/src/main/cpp/examples/AddressableLED/cpp/Robot.cpp

@@ -0,0 +1,50 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <array>
+
+#include <frc/AddressableLED.h>
+#include <frc/TimedRobot.h>
+#include <frc/smartdashboard/SmartDashboard.h>
+
+class Robot : public frc::TimedRobot {
+  // PWM port 0
+  // Must be a PWM header, not MXP or DIO
+  frc::AddressableLED m_led{0};
+  std::array<frc::AddressableLED::LEDData, 12> m_ledBuffer;  // Reuse the buffer
+  int m_count = 0;
+
+ public:
+  void RobotInit() override {
+    // Default to a length of 12, start empty output
+    // Length is expensive to set, so only set it once, then just update data
+    m_led.SetLength(12);
+    m_led.SetData(m_ledBuffer);
+    m_led.Start();
+  }
+
+  void RobotPeriodic() override {
+    // Zero out all LEDs
+    for (auto& ledData : m_ledBuffer) {
+      ledData.SetLED(0, 0, 0);
+    }
+
+    // Set 1 single LED to red
+    m_ledBuffer[m_count].SetLED(50, 0, 0);
+
+    // Continue moving LED
+    m_count++;
+    if (m_count >= 12) m_count = 0;
+
+    // Buffer must be written to update.
+    m_led.SetData(m_ledBuffer);
+  }
+};
+
+#ifndef RUNNING_FRC_TESTS
+int main() { return frc::StartRobot<Robot>(); }
+#endif

wpilibcExamples/src/main/cpp/examples/DMA/cpp/Robot.cpp

@@ -0,0 +1,82 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <frc/AnalogInput.h>
+#include <frc/DMA.h>
+#include <frc/DMASample.h>
+#include <frc/DigitalOutput.h>
+#include <frc/Encoder.h>
+#include <frc/TimedRobot.h>
+#include <frc/smartdashboard/SmartDashboard.h>
+
+class Robot : public frc::TimedRobot {
+  frc::DMA m_dma;  // DMA object
+
+  // DMA needs a trigger, can use an output as trigger.
+  // 8 Triggers exist per DMA object, can be triggered on any
+  // DigitalSource.
+  frc::DigitalOutput m_dmaTrigger{2};
+
+  // Analog input to read with DMA
+  frc::AnalogInput m_analogInput{0};
+
+  // Encoder to read with DMA
+  frc::Encoder m_encoder{0, 1};
+
+ public:
+  void RobotInit() override {
+    // Trigger on falling edge of dma trigger output
+    m_dma.SetExternalTrigger(&m_dmaTrigger, false, true);
+
+    // Add inputs we want to read via DMA
+    m_dma.AddAnalogInput(&m_analogInput);
+    m_dma.AddEncoder(&m_encoder);
+    m_dma.AddEncoderPeriod(&m_encoder);
+
+    // Make sure trigger is set to off.
+    m_dmaTrigger.Set(true);
+
+    // Start DMA. No triggers or inputs can be added after this call
+    // unless DMA is stopped.
+    m_dma.StartDMA(1024);
+  }
+
+  void RobotPeriodic() override {
+    // Manually Trigger DMA read
+    m_dmaTrigger.Set(false);
+
+    // Need to create a sample.
+    frc::DMASample sample;
+    int32_t remaining = 0;
+    int32_t status = 0;
+    // Update our sample. remaining is the number of samples remaining in the
+    // buffer status is more specfic error messages if readStatus is not OK.
+    // Wait 1ms if buffer is empty
+    HAL_DMAReadStatus readStatus =
+        sample.Update(&m_dma, 1_ms, &remaining, &status);
+
+    if (readStatus == HAL_DMA_OK) {
+      // Status value in all these reads should be checked, a non 0 value means
+      // value could not be read
+
+      // If DMA is good, values exist
+      auto encoderDistance = sample.GetEncoderDistance(&m_encoder, &status);
+      // Period is not scaled, and is a raw value
+      auto encoderPeriod = sample.GetEncoderPeriodRaw(&m_encoder, &status);
+      auto analogVoltage =
+          sample.GetAnalogInputVoltage(&m_analogInput, &status);
+
+      frc::SmartDashboard::PutNumber("Distance", encoderDistance);
+      frc::SmartDashboard::PutNumber("Period", encoderPeriod);
+      frc::SmartDashboard::PutNumber("Input", analogVoltage);
+    }
+  }
+};
+
+#ifndef RUNNING_FRC_TESTS
+int main() { return frc::StartRobot<Robot>(); }
+#endif

wpilibcExamples/src/main/cpp/examples/DutyCycleEncoder/cpp/Robot.cpp

@@ -0,0 +1,48 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <frc/DigitalInput.h>
+#include <frc/DutyCycle.h>
+#include <frc/DutyCycleEncoder.h>
+#include <frc/TimedRobot.h>
+#include <frc/smartdashboard/SmartDashboard.h>
+
+class Robot : public frc::TimedRobot {
+  frc::DigitalInput m_input{0};  // Input channel
+
+  // Duty cycle encoder
+  frc::DutyCycleEncoder m_dutyCycleEncoder{m_input};
+
+ public:
+  void RobotInit() override {
+    // Set to 0.5 units per rotation
+    m_dutyCycleEncoder.SetDistancePerRotation(0.5);
+  }
+
+  void RobotPeriodic() override {
+    // Connected can be checked, and uses the frequency of the encoder
+    auto connected = m_dutyCycleEncoder.IsConnected();
+
+    // Duty Cycle Frequency in Hz
+    auto frequency = m_dutyCycleEncoder.GetFrequency();
+
+    // Output of encoder
+    auto output = m_dutyCycleEncoder.Get();
+
+    // Output scaled by DistancePerPulse
+    auto distance = m_dutyCycleEncoder.GetDistance();
+
+    frc::SmartDashboard::PutBoolean("Connected", connected);
+    frc::SmartDashboard::PutNumber("Frequency", frequency);
+    frc::SmartDashboard::PutNumber("Output", output.to<double>());
+    frc::SmartDashboard::PutNumber("Distance", distance);
+  }
+};
+
+#ifndef RUNNING_FRC_TESTS
+int main() { return frc::StartRobot<Robot>(); }
+#endif

wpilibcExamples/src/main/cpp/examples/DutyCycleInput/cpp/Robot.cpp

@@ -0,0 +1,35 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <frc/DigitalInput.h>
+#include <frc/DutyCycle.h>
+#include <frc/TimedRobot.h>
+#include <frc/smartdashboard/SmartDashboard.h>
+
+class Robot : public frc::TimedRobot {
+  frc::DigitalInput m_input{0};         // Input channel
+  frc::DutyCycle m_dutyCycle{m_input};  // Duty cycle input
+
+ public:
+  void RobotInit() override {}
+
+  void RobotPeriodic() override {
+    // Duty Cycle Frequency in Hz
+    auto frequency = m_dutyCycle.GetFrequency();
+
+    // Output of duty cycle, ranging from 0 to 1
+    // 1 is fully on, 0 is fully off
+    auto output = m_dutyCycle.GetOutput();
+
+    frc::SmartDashboard::PutNumber("Frequency", frequency);
+    frc::SmartDashboard::PutNumber("Duty Cycle", output);
+  }
+};
+
+#ifndef RUNNING_FRC_TESTS
+int main() { return frc::StartRobot<Robot>(); }
+#endif

wpilibcExamples/src/main/cpp/examples/examples.json

@@ -428,5 +428,45 @@
     "foldername": "TankDriveXboxController",
     "gradlebase": "cpp",
     "commandversion": 1
+  },
+  {
+    "name": "Duty Cycle Encoder",
+    "description": "Demonstrates the use of the Duty Cycle Encoder class",
+    "tags": [
+      "Getting Started with C++"
+    ],
+    "foldername": "DutyCycleEncoder",
+    "gradlebase": "cpp",
+    "commandversion": 2
+  },
+  {
+    "name": "Duty Cycle Input",
+    "description": "Demonstrates the use of the Duty Cycle class",
+    "tags": [
+      "Getting Started with C++"
+    ],
+    "foldername": "DutyCycleInput",
+    "gradlebase": "cpp",
+    "commandversion": 2
+  },
+  {
+    "name": "Addressable LED",
+    "description": "Demonstrates the use of the Addressable LED class",
+    "tags": [
+      "Getting Started with C++"
+    ],
+    "foldername": "AddressableLED",
+    "gradlebase": "cpp",
+    "commandversion": 2
+  },
+  {
+    "name": "DMA",
+    "description": "Demonstrates the use of the DMA class",
+    "tags": [
+      "Advanced C++"
+    ],
+    "foldername": "DMA",
+    "gradlebase": "cpp",
+    "commandversion": 2
   }
 ]