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Merge pull request #12 from ABOSTM/master
Create examples for HardwareTimer library
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Diff for: ‎examples/Peripherals/HardwareTimer/All-in-one_setPWM/All-in-one_setPWM.ino

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/*
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All-in-one setPWM
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This example shows how to configure a PWM with HardwareTimer in one single function call.
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PWM is generated on `LED_BUILTIN` if available.
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No interruption callback used: PWM is generated by hardware.
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Once configured, there is no CPU load.
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*/
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#if defined(LED_BUILTIN)
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#define pin LED_BUILTIN
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#else
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#define pin D2
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#endif
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void setup()
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{
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// no need to configure pin, it will be done by HardwareTimer configuration
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// pinMode(pin, OUTPUT);
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// Automatically retrieve TIM instance and channel associated to pin
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// This is used to be compatible with all STM32 series automatically.
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TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pin), PinMap_PWM);
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uint32_t channel = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pin), PinMap_PWM));
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// Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup() function is finished.
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HardwareTimer *MyTim = new HardwareTimer(Instance);
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// Configure and start PWM
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// MyTim->setPWM(channel, pin, 5, 10, NULL, NULL); // No callback required, we can simplify the function call
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MyTim->setPWM(channel, pin, 5, 10); // 5 Hertz, 10% dutycycle
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}
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void loop()
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{
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/* Nothing to do all is done by hardware. Even no interrupt required. */
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}

Diff for: ‎examples/Peripherals/HardwareTimer/Frequency_Dutycycle_measurement/Frequency_Dutycycle_measurement.ino

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/*
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Frequency and dutycycle measurement
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This example shows how to configure HardwareTimer to measure external signal frequency and dutycycle.
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The input pin will be connected to 2 channel of the timer, one for rising edge the other for falling edge.
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Each time a rising edge is detected on the input pin, hardware will save counter value into one of the CaptureCompare register.
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Each time a falling edge is detected on the input pin, hardware will save counter value into the other CaptureCompare register.
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External signal (signal generator for example) should be connected to `D2`.
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*/
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#define pin D2
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uint32_t channelRising, channelFalling;
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volatile uint32_t FrequencyMeasured, DutycycleMeasured, LastPeriodCapture = 0, CurrentCapture, HighStateMeasured;
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uint32_t input_freq = 0;
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HardwareTimer *MyTim;
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/**
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@brief Input capture interrupt callback : Compute frequency and dutycycle of input signal
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*/
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void TIMINPUT_Capture_Rising_IT_callback(HardwareTimer*)
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{
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CurrentCapture = MyTim->getCaptureCompare(channelRising);
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/* frequency computation */
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if (CurrentCapture > LastPeriodCapture)
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{
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FrequencyMeasured = input_freq / (CurrentCapture - LastPeriodCapture);
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DutycycleMeasured = (HighStateMeasured * 100) / (CurrentCapture - LastPeriodCapture);
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}
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else if (CurrentCapture <= LastPeriodCapture)
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{
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/* 0x1000 is max overflow value */
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FrequencyMeasured = input_freq / (0x10000 + CurrentCapture - LastPeriodCapture);
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DutycycleMeasured = (HighStateMeasured * 100) / (0x10000 + CurrentCapture - LastPeriodCapture);
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}
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LastPeriodCapture = CurrentCapture;
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}
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/**
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@brief Input capture interrupt callback : Compute frequency and dutycycle of input signal
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*/
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void TIMINPUT_Capture_Falling_IT_callback(HardwareTimer*)
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{
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/* prepare DutyCycle computation */
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CurrentCapture = MyTim->getCaptureCompare(channelFalling);
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if (CurrentCapture > LastPeriodCapture)
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{
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HighStateMeasured = CurrentCapture - LastPeriodCapture;
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}
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else if (CurrentCapture <= LastPeriodCapture)
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{
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/* 0x1000 is max overflow value */
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HighStateMeasured = 0x10000 + CurrentCapture - LastPeriodCapture;
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}
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}
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void setup()
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{
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Serial.begin(115200);
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// Automatically retrieve TIM instance and channelRising associated to pin
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// This is used to be compatible with all STM32 series automatically.
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TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pin), PinMap_PWM);
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channelRising = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pin), PinMap_PWM));
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// channelRisings come by pair for TIMER_INPUT_FREQ_DUTY_MEASUREMENT mode:
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// channelRising1 is associated to channelFalling and channelRising3 is associated with channelRising4
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switch (channelRising) {
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case 1:
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channelFalling = 2;
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break;
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case 2:
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channelFalling = 1;
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break;
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case 3:
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channelFalling = 4;
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break;
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case 4:
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channelFalling = 3;
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break;
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}
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// Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup() function is finished.
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MyTim = new HardwareTimer(Instance);
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// Configure rising edge detection to measure frequency
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MyTim->setMode(channelRising, TIMER_INPUT_FREQ_DUTY_MEASUREMENT, pin);
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// With a PrescalerFactor = 1, the minimum frequency value to measure is : TIM counter clock / CCR MAX
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// = (SystemCoreClock) / 65535
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// Example on Nucleo_L476RG with systemClock at 80MHz, the minimum frequency is around 1,2 khz
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// To reduce minimum frequency, it is possible to increase prescaler. But this is at a cost of precision.
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// The maximum frequency depends on processing of both interruptions and thus depend on board used
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// Example on Nucleo_L476RG with systemClock at 80MHz the interruptions processing is around 10 microseconds and thus Max frequency is around 100kHz
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uint32_t PrescalerFactor = 1;
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MyTim->setPrescaleFactor(PrescalerFactor);
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MyTim->setOverflow(0x10000); // Max Period value to have the largest possible time to detect rising edge and avoid timer rollover
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MyTim->attachInterrupt(channelRising, TIMINPUT_Capture_Rising_IT_callback);
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MyTim->attachInterrupt(channelFalling, TIMINPUT_Capture_Falling_IT_callback);
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MyTim->resume();
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// Compute this scale factor only once
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input_freq = MyTim->getTimerClkFreq() / MyTim->getPrescaleFactor();
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}
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void loop()
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{
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/* Print frequency and dutycycle measured on Serial monitor every seconds */
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Serial.print((String)"Frequency = " + FrequencyMeasured);
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Serial.println((String)" Dutycycle = " + DutycycleMeasured);
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delay(1000);
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}

Diff for: ‎examples/Peripherals/HardwareTimer/InputCapture/InputCapture.ino

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/*
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Input capture
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This example shows how to configure HardwareTimer in inputcapture to measure external signal frequency.
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Each time a rising edge is detected on the input pin, hardware will save counter value into CaptureCompare register.
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External signal (signal generator for example) should be connected to `D2`.
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Measured frequency is displayed on Serial Monitor.
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*/
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#define pin D2
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uint32_t channel;
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volatile uint32_t FrequencyMeasured, LastCapture = 0, CurrentCapture;
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uint32_t input_freq = 0;
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HardwareTimer *MyTim;
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void InputCapture_IT_callback(HardwareTimer*)
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{
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CurrentCapture = MyTim->getCaptureCompare(channel);
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/* frequency computation */
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if (CurrentCapture > LastCapture) {
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FrequencyMeasured = input_freq / (CurrentCapture - LastCapture);
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}
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else if (CurrentCapture <= LastCapture) {
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/* 0x1000 is max overflow value */
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FrequencyMeasured = input_freq / (0x10000 + CurrentCapture - LastCapture);
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}
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LastCapture = CurrentCapture;
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}
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void setup()
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{
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Serial.begin(115200);
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// Automatically retrieve TIM instance and channel associated to pin
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// This is used to be compatible with all STM32 series automatically.
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TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pin), PinMap_PWM);
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channel = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pin), PinMap_PWM));
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// Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup() function is finished.
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MyTim = new HardwareTimer(Instance);
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// Configure rising edge detection to measure frequency
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MyTim->setMode(channel, TIMER_INPUT_CAPTURE_RISING, pin);
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// With a PrescalerFactor = 1, the minimum frequency value to measure is : TIM counter clock / CCR MAX
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// = (SystemCoreClock) / 65535
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// Example on Nucleo_L476RG with systemClock at 80MHz, the minimum frequency is around 1,2 khz
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// To reduce minimum frequency, it is possible to increase prescaler. But this is at a cost of precision.
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// The maximum frequency depends on processing of the interruption and thus depend on board used
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// Example on Nucleo_L476RG with systemClock at 80MHz the interruption processing is around 4,5 microseconds and thus Max frequency is around 220kHz
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uint32_t PrescalerFactor = 1;
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MyTim->setPrescaleFactor(PrescalerFactor);
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MyTim->setOverflow(0x10000); // Max Period value to have the largest possible time to detect rising edge and avoid timer rollover
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MyTim->attachInterrupt(channel, InputCapture_IT_callback);
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MyTim->resume();
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// Compute this scale factor only once
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input_freq = MyTim->getTimerClkFreq() / MyTim->getPrescaleFactor();
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}
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void loop()
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{
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/* Print frequency measured on Serial monitor every seconds */
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Serial.println((String)"Frequency = " + FrequencyMeasured);
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delay(1000);
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}

Diff for: ‎examples/Peripherals/HardwareTimer/PWM_FullConfiguration/PWM_FullConfiguration.ino

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/*
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PWM full configuration
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This example shows how to fully configure a PWM with HardwareTimer.
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PWM is generated on `LED_BUILTIN` if available.
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PWM is generated by hardware: no CPU load.
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Nevertheless, in this example both interruption callback are used on Compare match (Falling edge of PWM1 mode) and update event (rising edge of PWM1 mode).
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Those call back are used to toggle a second pin: `pin2`.
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Once configured, there is only CPU load for callbacks executions.
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*/
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// 'pin' PWM will be mangaed automatically by hardware whereas 'pin2' PWM will be managed by software through interrupt callback
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#if defined(LED_BUILTIN)
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#define pin LED_BUILTIN
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#if LED_BUILTIN == D3
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#error LED_BUILTIN == D3
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#else
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#define pin2 D3
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#endif
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#else
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#define pin D2
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#define pin2 D3
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#endif
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void Update_IT_callback(HardwareTimer*)
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{ // Update event correspond to Rising edge of PWM when configured in PWM1 mode
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digitalWrite(pin2, LOW); // pin2 will be complementary to pin
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}
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void Compare_IT_callback(HardwareTimer*)
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{ // Compare match event correspond to falling edge of PWM when configured in PWM1 mode
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digitalWrite(pin2, HIGH);
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}
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void setup()
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{
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// No need to configure pin, it will be done by HardwareTimer configuration
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// pinMode(pin, OUTPUT);
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// Need to configure pin2, as it is not managed by HardwareTimer
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pinMode(pin2, OUTPUT);
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// Automatically retrieve TIM instance and channel associated to pin
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// This is used to be compatible with all STM32 series automatically.
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TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(digitalPinToPinName(pin), PinMap_PWM);
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uint32_t channel = STM_PIN_CHANNEL(pinmap_function(digitalPinToPinName(pin), PinMap_PWM));
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// Instantiate HardwareTimer object. Thanks to 'new' instantiation, HardwareTimer is not destructed when setup function is finished.
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HardwareTimer *MyTim = new HardwareTimer(Instance);
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MyTim->setMode(channel, TIMER_OUTPUT_COMPARE_PWM1, pin);
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// MyTim->setPrescaleFactor(8); // Due to setOverflow with MICROSEC_FORMAT, prescaler will be computed automatically based on timer input clock
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MyTim->setOverflow(100000, MICROSEC_FORMAT); // 10000 microseconds = 10 milliseconds
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MyTim->setCaptureCompare(channel, 50, PERCENT_COMPARE_FORMAT); // 50%
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MyTim->attachInterrupt(Update_IT_callback);
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MyTim->attachInterrupt(channel, Compare_IT_callback);
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MyTim->resume();
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}
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void loop()
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{
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/* Nothing to do all is done by hardware. Even no interrupt required. */
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}

Diff for: ‎examples/Peripherals/HardwareTimer/Timebase_callback/Timebase_callback.ino

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/*
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Timebase callback
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This example shows how to configure HardwareTimer to execute a callback at regular interval.
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Callback toggles pin.
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Once configured, there is only CPU load for callbacks executions.
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*/
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#if defined(LED_BUILTIN)
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#define pin LED_BUILTIN
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#else
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#define pin D2
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#endif
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void Update_IT_callback(HardwareTimer*)
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{ // Toggle pin. 10hz toogle --> 5Hz PWM
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digitalWrite(pin, !digitalRead(pin));
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}
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void setup()
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{
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#if defined(TIM1)
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TIM_TypeDef *Instance = TIM1;
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#else
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TIM_TypeDef *Instance = TIM2;
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#endif
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// Instantiate HardwareTimer object. Thanks to 'new' instanciation, HardwareTimer is not destructed when setup() function is finished.
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HardwareTimer *MyTim = new HardwareTimer(Instance);
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// configure pin in output mode
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pinMode(pin, OUTPUT);
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MyTim->setMode(2, TIMER_OUTPUT_COMPARE); // In our case, channekFalling is configured but not really used. Nevertheless it would be possible to attach a callback to channel compare match.
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MyTim->setOverflow(10, HERTZ_FORMAT); // 10 Hz
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MyTim->attachInterrupt(Update_IT_callback);
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MyTim->resume();
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}
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void loop()
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{
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/* Nothing to do all is done by hardware. Even no interrupt required. */
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}

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