src/lib/HWTIMER/ESP8266_hwTimer.cpp

   1 #ifdef PLATFORM_ESP8266
   2 #include "ESP8266_hwTimer.h"
   3
   4 void inline hwTimer::nullCallback(void) {}
   5
   6 void (*hwTimer::callbackTick)() = &nullCallback;
   7 void (*hwTimer::callbackTock)() = &nullCallback;
   8
   9 volatile uint32_t hwTimer::HWtimerInterval = TimerIntervalUSDefault;
  10 volatile bool hwTimer::isTick = false;
  11 volatile int32_t hwTimer::PhaseShift = 0;
  12 volatile int32_t hwTimer::FreqOffset = 0;
  13 bool hwTimer::running = false;
  14 uint32_t hwTimer::NextTimeout;
  15
  16 #define HWTIMER_TICKS_PER_US 5
  17 #define HWTIMER_PRESCALER (clockCyclesPerMicrosecond() / HWTIMER_TICKS_PER_US)
  18
  19
  20 void hwTimer::init()
  21 {
  22     timer0_isr_init();
  23     running = false;
  24 }
  25
  26 void hwTimer::stop()
  27 {
  28     if (running)
  29     {
  30         timer0_detachInterrupt();
  31         running = false;
  32     }
  33 }
  34
  35 void ICACHE_RAM_ATTR hwTimer::resume()
  36 {
  37     if (!running)
  38     {
  39         noInterrupts();
  40         timer0_attachInterrupt(hwTimer::callback);
  41         // The STM32 timer fires tock() ASAP after enabling, so mimic that behavior
  42         // tock() should always be the first event to maintain consistency
  43         isTick = false;
  44         // Fire the timer in 2us to get it started close to now
  45         NextTimeout = ESP.getCycleCount() + (2 * HWTIMER_TICKS_PER_US * HWTIMER_PRESCALER);
  46         timer0_write(NextTimeout);
  47         interrupts();
  48
  49         running = true;
  50     }
  51 }
  52
  53 void hwTimer::updateInterval(uint32_t newTimerInterval)
  54 {
  55     // timer should not be running when updateInterval() is called
  56     hwTimer::HWtimerInterval = newTimerInterval * (HWTIMER_TICKS_PER_US * HWTIMER_PRESCALER);
  57 }
  58
  59 void ICACHE_RAM_ATTR hwTimer::resetFreqOffset()
  60 {
  61     FreqOffset = 0;
  62 }
  63
  64 void ICACHE_RAM_ATTR hwTimer::incFreqOffset()
  65 {
  66     FreqOffset++;
  67 }
  68
  69 void ICACHE_RAM_ATTR hwTimer::decFreqOffset()
  70 {
  71     FreqOffset--;
  72 }
  73
  74 void ICACHE_RAM_ATTR hwTimer::phaseShift(int32_t newPhaseShift)
  75 {
  76     int32_t minVal = -(hwTimer::HWtimerInterval >> 2);
  77     int32_t maxVal = (hwTimer::HWtimerInterval >> 2);
  78
  79     // phase shift is in microseconds
  80     hwTimer::PhaseShift = constrain(newPhaseShift, minVal, maxVal) * (HWTIMER_TICKS_PER_US * HWTIMER_PRESCALER);
  81 }
  82
  83 void ICACHE_RAM_ATTR hwTimer::callback()
  84 {
  85     if (!running)
  86     {
  87         return;
  88     }
  89
  90     NextTimeout += (hwTimer::HWtimerInterval >> 1) + (FreqOffset * HWTIMER_PRESCALER);
  91     if (hwTimer::isTick)
  92     {
  93         timer0_write(NextTimeout);
  94         hwTimer::callbackTick();
  95     }
  96     else
  97     {
  98         NextTimeout += hwTimer::PhaseShift;
  99         timer0_write(NextTimeout);
 100         hwTimer::PhaseShift = 0;
 101         hwTimer::callbackTock();
 102     }
 103     hwTimer::isTick = !hwTimer::isTick;
 104 }
 105 #endif