Andrew Boyson / clock

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Dependents:   oldheating gps motorhome heating

timer.c@34:aeb58975e61a, 2018-11-30 (annotated)

Committer:
andrewboyson
Date:
Fri Nov 30 19:23:48 2018 +0000
Revision:
34:aeb58975e61a
Parent:
33:b9e3c06e7dab 
Corrected unsigned comparison in TimerIntervalHasElapsed.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 24:6c9833e2a049 1 #include <stdint.h>
andrewboyson 26:0421132e6eaf 2 #include <stdbool.h>
andrewboyson 24:6c9833e2a049 3
andrewboyson 25:81014a201736 4 #include "timer.h"
andrewboyson 33:b9e3c06e7dab 5 #include "tick.h"
andrewboyson 24:6c9833e2a049 6
andrewboyson 30:212ca42b8779 7 #define TCR (*((volatile unsigned *) 0x40004004))
andrewboyson 30:212ca42b8779 8 #define TC (*((volatile unsigned *) 0x40004008))
andrewboyson 30:212ca42b8779 9 #define PR (*((volatile unsigned *) 0x4000400C))
andrewboyson 30:212ca42b8779 10 #define MCR (*((volatile unsigned *) 0x40004014))
andrewboyson 30:212ca42b8779 11 #define CTCR (*((volatile unsigned *) 0x40004070))
andrewboyson 30:212ca42b8779 12
andrewboyson 26:0421132e6eaf 13 uint32_t TimerNowCount()
andrewboyson 26:0421132e6eaf 14 {
andrewboyson 30:212ca42b8779 15 return TC;
andrewboyson 24:6c9833e2a049 16 }
andrewboyson 26:0421132e6eaf 17 uint32_t TimerIntervalCount(uint32_t* pLastCount)
andrewboyson 24:6c9833e2a049 18 {
andrewboyson 30:212ca42b8779 19 uint32_t thisCount = TC;
andrewboyson 24:6c9833e2a049 20 uint32_t period = thisCount - *pLastCount;
andrewboyson 24:6c9833e2a049 21 *pLastCount = thisCount;
andrewboyson 24:6c9833e2a049 22 return period;
andrewboyson 24:6c9833e2a049 23 }
andrewboyson 24:6c9833e2a049 24 uint32_t TimerSinceCount(uint32_t startCount)
andrewboyson 24:6c9833e2a049 25 {
andrewboyson 30:212ca42b8779 26 return TC - startCount;
andrewboyson 24:6c9833e2a049 27 }
andrewboyson 24:6c9833e2a049 28 uint32_t TimerSinceMs(uint32_t startCount)
andrewboyson 24:6c9833e2a049 29 {
andrewboyson 30:212ca42b8779 30 uint32_t count = TC - startCount;
andrewboyson 25:81014a201736 31 return count / TIMER_COUNT_PER_MS;
andrewboyson 24:6c9833e2a049 32 }
andrewboyson 26:0421132e6eaf 33
andrewboyson 33:b9e3c06e7dab 34 bool TimerIntervalHasElapsed(uint32_t* pBaseCount, uint32_t intervalCount)
andrewboyson 26:0421132e6eaf 35 {
andrewboyson 34:aeb58975e61a 36 if (TC - *pBaseCount > intervalCount) //All unsigned wrap around arithmetic
andrewboyson 33:b9e3c06e7dab 37 {
andrewboyson 33:b9e3c06e7dab 38 *pBaseCount += intervalCount;
andrewboyson 33:b9e3c06e7dab 39 return true;
andrewboyson 33:b9e3c06e7dab 40 }
andrewboyson 33:b9e3c06e7dab 41 return false;
andrewboyson 26:0421132e6eaf 42 }
andrewboyson 33:b9e3c06e7dab 43
andrewboyson 33:b9e3c06e7dab 44 int32_t TimerMultiplyFractionalPart(int32_t value, uint32_t timerCountSinceStart, uint32_t interval)
andrewboyson 26:0421132e6eaf 45 {
andrewboyson 26:0421132e6eaf 46 int64_t fraction;
andrewboyson 26:0421132e6eaf 47
andrewboyson 33:b9e3c06e7dab 48 fraction = timerCountSinceStart;
andrewboyson 26:0421132e6eaf 49 fraction <<= 32;
andrewboyson 33:b9e3c06e7dab 50 fraction /= interval;
andrewboyson 26:0421132e6eaf 51
andrewboyson 26:0421132e6eaf 52 return (value * fraction) >> 32;
andrewboyson 26:0421132e6eaf 53 }
andrewboyson 26:0421132e6eaf 54
andrewboyson 26:0421132e6eaf 55 void TimerInit()
andrewboyson 26:0421132e6eaf 56 {
andrewboyson 30:212ca42b8779 57 TCR = 2; // 21.6.2 Timer Control Register - Reset TC and PC.
andrewboyson 30:212ca42b8779 58 CTCR = 0; // 21.6.3 Count Control Register - Timer mode
andrewboyson 30:212ca42b8779 59 PR = 0; // 21.6.5 Prescale register - Don't prescale 96MHz clock (divide by PR+1).
andrewboyson 30:212ca42b8779 60 MCR = 0; // 21.6.8 Match Control Register - no interrupt or reset
andrewboyson 30:212ca42b8779 61 TCR = 1; // 21.6.2 Timer Control Register - Enable TC and PC
andrewboyson 26:0421132e6eaf 62 }