FastPWM_STM_TIM.cpp

00001 //This should (hopefully) work on all STM targets which use TIM timers for PWM
00002 
00003 #ifdef TARGET_STM
00004 
00005 #include "FastPWM.h"
00006 
00007 typedef __IO uint32_t* CHANNEL_P_T;
00008 
00009 #define PWM_CHANNEL     (**(CHANNEL_P_T*)fast_obj)
00010 #define PWM_TIMER       ((TIM_TypeDef*)_pwm.pwm)
00011 
00012 extern CHANNEL_P_T getChannel(TIM_TypeDef* pwm, PinName pin);
00013 
00014 void FastPWM::initFastPWM( void ) {
00015     fast_obj = new (CHANNEL_P_T);
00016     *(CHANNEL_P_T*)fast_obj = getChannel(PWM_TIMER, _pwm.pin);
00017     
00018     //Enable PWM period syncing for glitch free result
00019     PWM_TIMER->CR1 |= TIM_CR1_ARPE;
00020     
00021     bits = 16;
00022 }
00023 
00024 void FastPWM::pulsewidth_ticks( uint32_t ticks ) {
00025     PWM_CHANNEL = ticks;    
00026 }
00027 
00028 void FastPWM::period_ticks( uint32_t ticks ) {
00029     PWM_TIMER->ARR = ticks - 1;
00030 }
00031 
00032 uint32_t FastPWM::getPeriod( void ) {
00033     return PWM_TIMER->ARR + 1;
00034 }
00035 
00036 uint32_t FastPWM::setPrescaler(uint32_t reqScale) {
00037     if (reqScale == 0)
00038         //Return prescaler
00039         return PWM_TIMER->PSC + 1;
00040     if (reqScale > (uint32_t)(1<<16))
00041         reqScale = 1<<16;
00042     //Else set prescaler, we have to substract one from reqScale since a 0 in PCVAL is prescaler of 1
00043     PWM_TIMER->PSC = reqScale - 1;
00044 
00045     return reqScale;
00046 }
00047 
00048 #endif