Add support for setting the channel input filter (#2136)

* Add support for setting the channel input filter

* Format with astyle

* Start enum from 0 so we can directly convert enum to filter value

Author: dberlin

cores/arduino/HardwareTimer.h

@@ -90,6 +90,25 @@ typedef enum {
   PERCENT_COMPARE_FORMAT, // used for Dutycycle
 } TimerCompareFormat_t;
 
+typedef enum {
+  FILTER_NONE = 0,  // No filter
+  FILTER_CKINT_N2,  // Sampling rate is same as clock interrupt, n=2 events
+  FILTER_CKINT_N4,  // Sampling rate is same as clock interrupt, n=4 events
+  FILTER_CKINT_N8,  // Sampling rate is same as clock interrupt, n=8 events
+  FILTER_DTS2_N6,   // Sampling rate is DTS/2, n=6 events
+  FILTER_DTS2_N8,   // Sampling rate is DTS/2, n=8 events
+  FILTER_DTS4_N6,   // Sampling rate is DTS/4, n=6 events
+  FILTER_DTS4_N8,   // Sampling rate is DTS/4, n=8 events
+  FILTER_DTS8_N6,   // Sampling rate is DTS/8, n=6 events
+  FILTER_DTS8_N8,   // Sampling rate is DTS/8, n=8 events
+  FILTER_DTS16_N5,  // Sampling rate is DTS/16, n=5 events
+  FILTER_DTS16_N6,  // Sampling rate is DTS/16, n=6 events
+  FILTER_DTS16_N8,  // Sampling rate is DTS/16, n=8 events
+  FILTER_DTS32_N5,  // Sampling rate is DTS/32, n=5 events
+  FILTER_DTS32_N6,  // Sampling rate is DTS/32, n=6 events
+  FILTER_DTS32_N8,  // Sampling rate is DTS/32, n=8 events
+} ChannelInputFilter_t;
+
 #ifdef __cplusplus
 
 #include <functional>
@@ -121,8 +140,8 @@ class HardwareTimer {
     void setCount(uint32_t val, TimerFormat_t format = TICK_FORMAT); // set timer counter to value 'val' depending on format provided
     uint32_t getCount(TimerFormat_t format = TICK_FORMAT);  // return current counter value of timer depending on format provided
 
-    void setMode(uint32_t channel, TimerModes_t mode, PinName pin = NC); // Configure timer channel with specified mode on specified pin if available
-    void setMode(uint32_t channel, TimerModes_t mode, uint32_t pin);
+    void setMode(uint32_t channel, TimerModes_t mode, PinName pin = NC, ChannelInputFilter_t filter = FILTER_NONE); // Configure timer channel with specified mode on specified pin if available
+    void setMode(uint32_t channel, TimerModes_t mode, uint32_t pin, ChannelInputFilter_t filter = FILTER_NONE);
 
     TimerModes_t getMode(uint32_t channel);  // Retrieve configured mode
 

libraries/SrcWrapper/src/HardwareTimer.cpp

@@ -619,9 +619,9 @@ void HardwareTimer::setCount(uint32_t counter, TimerFormat_t format)
   * @param  pin: Arduino pin number, ex: D1, 1 or PA1
   * @retval None
   */
-void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, uint32_t pin)
+void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, uint32_t pin, ChannelInputFilter_t filter)
 {
-  setMode(channel, mode, digitalPinToPinName(pin));
+  setMode(channel, mode, digitalPinToPinName(pin), filter);
 }
 
 /**
@@ -631,7 +631,7 @@ void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, uint32_t pin)
   * @param  pin: pin name, ex: PB_0
   * @retval None
   */
-void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, PinName pin)
+void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, PinName pin, ChannelInputFilter_t filter)
 {
   int timChannel = getChannel(channel);
   int timAssociatedInputChannel;
@@ -659,7 +659,7 @@ void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, PinName pin)
   channelIC.ICPolarity = TIM_ICPOLARITY_RISING;
   channelIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
   channelIC.ICPrescaler = TIM_ICPSC_DIV1;
-  channelIC.ICFilter = 0;
+  channelIC.ICFilter = filter;
 
   switch (mode) {
     case TIMER_DISABLED: