added prescaler for 16 bit pwm in LPC1347 target
Fork of mbed-dev by
Diff: targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c
- Revision:
- 50:a417edff4437
- Parent:
- 0:9b334a45a8ff
- Child:
- 144:ef7eb2e8f9f7
--- a/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c Wed Jan 13 12:45:11 2016 +0000 +++ b/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c Fri Jan 15 07:45:16 2016 +0000 @@ -46,11 +46,28 @@ static int pwm_prescaler_div; -uint32_t pwmout_get_channel_route(pwmout_t *obj) +float pwmout_calculate_duty(uint32_t width_cycles, uint32_t period_cycles); +void pwmout_write_channel(uint32_t channel, float value); + +uint32_t pwmout_get_channel_route(uint32_t channel) { - MBED_ASSERT(obj->channel != (PWMName) NC); + MBED_ASSERT(channel != (PWMName) NC); - switch (obj->channel) { + switch (channel) { +#ifdef TIMER_ROUTEPEN_CC0PEN + case PWM_CH0: + return TIMER_ROUTEPEN_CC0PEN; + break; + case PWM_CH1: + return TIMER_ROUTEPEN_CC1PEN; + break; + case PWM_CH2: + return TIMER_ROUTEPEN_CC2PEN; + break; + case PWM_CH3: + return TIMER_ROUTEPEN_CC3PEN; + break; +#else case PWM_CH0: return TIMER_ROUTE_CC0PEN; break; @@ -60,11 +77,75 @@ case PWM_CH2: return TIMER_ROUTE_CC2PEN; break; +#endif default: return 0; } } +/* +* Disables the route location given. Returns true if it was enabled, false if it wasn't. +*/ +bool pwmout_disable_channel_route(uint32_t routeloc) { +#ifdef TIMER_ROUTEPEN_CC0PEN + if(PWM_TIMER->ROUTEPEN & routeloc) { + //This channel was in use, so disable + PWM_TIMER->ROUTEPEN &= ~routeloc; + return true; + } +#else + if(PWM_TIMER->ROUTE & routeloc) { + //This channel was in use, so disable + PWM_TIMER->ROUTE &= ~routeloc; + return true; + } +#endif + return false; +} + +/* +* Check if a channel is active +*/ +bool pwmout_channel_route_active(uint32_t routeloc) { +#ifdef TIMER_ROUTEPEN_CC0PEN + if(PWM_TIMER->ROUTEPEN & routeloc) { + return true; + } +#else + if(PWM_TIMER->ROUTE & routeloc) { + return true; + } +#endif + return false; +} + +/* +* Set the given route PEN flag +*/ +void pwmout_set_channel_route(uint32_t routeloc) { +#ifdef TIMER_ROUTEPEN_CC0PEN + PWM_TIMER->ROUTEPEN |= routeloc; +#else + PWM_TIMER->ROUTE |= routeloc; +#endif +} + +/* +* Check if all routes are disabled +*/ +bool pwmout_all_inactive(void) { +#ifdef TIMER_ROUTEPEN_CC0PEN + if(PWM_TIMER->ROUTEPEN == _TIMER_ROUTEPEN_RESETVALUE) { + return true; + } +#else + if(PWM_TIMER->ROUTE == PWM_ROUTE) { + return true; + } +#endif + return false; +} + void pwmout_enable_pins(pwmout_t *obj, uint8_t enable) { if (enable) { @@ -75,17 +156,14 @@ } } -void pwmout_enable(pwmout_t *obj, uint8_t enable) -{ - /* Start with default CC (Compare/Capture) channel parameters */ - TIMER_InitCC_TypeDef timerCCInit = TIMER_INITCC_DEFAULT; +void pwmout_enable(pwmout_t *obj, uint8_t enable){ if (enable) { - /* Set mode to PWM */ - timerCCInit.mode = timerCCModePWM; + // Set mode to PWM + PWM_TIMER->CC[obj->channel].CTRL = TIMER_CC_CTRL_MODE_PWM; + } else { + // Set mode to default (== disabled) + PWM_TIMER->CC[obj->channel].CTRL = _TIMER_CC_CTRL_MODE_DEFAULT; } - - /* Configure CC channel */ - TIMER_InitCC(PWM_TIMER, obj->channel, &timerCCInit); } void pwmout_init(pwmout_t *obj, PinName pin) @@ -103,62 +181,107 @@ TIMER_Init(PWM_TIMER, &timerInit); } - /* Enable correct channel */ - uint32_t routeloc = pwmout_get_channel_route(obj); - if(PWM_TIMER->ROUTE & routeloc) { + // Set route enable + if(pwmout_channel_route_active(pwmout_get_channel_route(obj->channel))) { //This channel was already in use - //TODO: gracefully handle this case + //TODO: gracefully handle this case. mbed_error? + return; } else { - //This channel was unused up to now - PWM_TIMER->ROUTE |= routeloc; + pwmout_set_channel_route(pwmout_get_channel_route(obj->channel)); blockSleepMode(EM1); - - //TODO: check if any channel was up already, then don't re-init timer pwmout_enable(obj, true); pwmout_enable_pins(obj, true); } - /* Route correct channel to location 1 */ + // Set route location +#ifdef _TIMER_ROUTELOC0_CC0LOC_LOC0 + switch (obj->channel) { + case PWM_CH0: + PWM_TIMER->ROUTELOC0 &= ~_TIMER_ROUTELOC0_CC0LOC_MASK; + PWM_TIMER->ROUTELOC0 |= pinmap_find_function(pin,PinMap_PWM) << _TIMER_ROUTELOC0_CC0LOC_SHIFT; + break; + case PWM_CH1: + PWM_TIMER->ROUTELOC0 &= ~_TIMER_ROUTELOC0_CC1LOC_MASK; + PWM_TIMER->ROUTELOC0 |= pinmap_find_function(pin,PinMap_PWM)<< _TIMER_ROUTELOC0_CC1LOC_SHIFT; + break; + case PWM_CH2: + PWM_TIMER->ROUTELOC0 &= ~_TIMER_ROUTELOC0_CC2LOC_MASK; + PWM_TIMER->ROUTELOC0 |= pinmap_find_function(pin,PinMap_PWM) << _TIMER_ROUTELOC0_CC2LOC_SHIFT; + break; + case PWM_CH3: + PWM_TIMER->ROUTELOC0 &= ~_TIMER_ROUTELOC0_CC3LOC_MASK; + PWM_TIMER->ROUTELOC0 |= pinmap_find_function(pin,PinMap_PWM) << _TIMER_ROUTELOC0_CC3LOC_SHIFT; + break; + default: + MBED_ASSERT(false); + } +#else + // On P1, the route location is statically defined for the entire timer. PWM_TIMER->ROUTE &= ~_TIMER_ROUTE_LOCATION_MASK; PWM_TIMER->ROUTE |= PWM_ROUTE; +#endif - /* Set default 20ms frequency and 0ms pulse width */ + // Set default 20ms frequency and 0ms pulse width pwmout_period(obj, 0.02); } void pwmout_free(pwmout_t *obj) { - uint32_t routeloc = pwmout_get_channel_route(obj); - if(PWM_TIMER->ROUTE & routeloc) { - //This channel was in use, so disable - PWM_TIMER->ROUTE &= ~routeloc; - pwmout_enable_pins(obj, false); + if(pwmout_disable_channel_route(pwmout_get_channel_route(obj->channel))) { + //Channel was previously enabled, so do housekeeping unblockSleepMode(EM1); - - //TODO: check if all channels are down, then switch off timer } else { //This channel was disabled already } + + pwmout_enable_pins(obj, false); + + if(pwmout_all_inactive()) { + //Stop timer + PWM_TIMER->CMD = TIMER_CMD_STOP; + while(PWM_TIMER->STATUS & TIMER_STATUS_RUNNING); + + //Disable clock + CMU_ClockEnable(PWM_TIMER_CLOCK, false); + } } void pwmout_write(pwmout_t *obj, float value) { + pwmout_write_channel(obj->channel, value); +} + +void pwmout_write_channel(uint32_t channel, float value) { + uint32_t width_cycles = 0; if (value < 0.0f) { - value = 0; - } else if (value > 1.0f) { - value = 1; + width_cycles = 0; + } else if (value >= 1.0f) { + width_cycles = PWM_TIMER->TOPB + 1; + } else { + width_cycles = (uint16_t)((float)PWM_TIMER->TOPB * value); } - float pulse_period_in_s = obj->period_cycles / ((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div)); - pwmout_pulsewidth(obj, value * pulse_period_in_s); + TIMER_CompareBufSet(PWM_TIMER, channel, width_cycles); } float pwmout_read(pwmout_t *obj) { - return obj->width_cycles / (float) obj->period_cycles; + return pwmout_calculate_duty(TIMER_CaptureGet(PWM_TIMER, obj->channel), TIMER_TopGet(PWM_TIMER)); } -// Set the PWM period, keeping the absolute pulse width the same. +float pwmout_calculate_duty(uint32_t width_cycles, uint32_t period_cycles) { + if(width_cycles > period_cycles) { + return 1.0f; + } + else if (width_cycles == 0) { + return 0.0f; + } + else { + return (float) width_cycles / (float) period_cycles; + } +} + +// Set the PWM period, keeping the duty cycle the same. void pwmout_period(pwmout_t *obj, float seconds) { // Find the lowest prescaler divider possible. @@ -181,13 +304,27 @@ } } - obj->period_cycles = cycles; + //Check if anything changed + if(((PWM_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) == (pwm_prescaler_div << _TIMER_CTRL_PRESC_SHIFT)) && (TIMER_TopGet(PWM_TIMER) == cycles)) return; + + //Save previous period for recalculation of duty cycles + uint32_t previous_period_cycles = PWM_TIMER->TOPB; //Set prescaler PWM_TIMER->CTRL = (PWM_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (pwm_prescaler_div << _TIMER_CTRL_PRESC_SHIFT); - /* Set Top Value, which controls the PWM period */ - TIMER_TopSet(PWM_TIMER, obj->period_cycles); + //Set Top Value, which controls the PWM period + TIMER_TopBufSet(PWM_TIMER, cycles); + + //For each active channel, re-calculate the compare value + uint32_t channel = 0; + while(pwmout_get_channel_route(channel) != 0) { + if(pwmout_channel_route_active(channel)) { + //recalc and reset compare value + pwmout_write_channel(channel, pwmout_calculate_duty(PWM_TIMER->CC[channel].CCVB, previous_period_cycles)); + } + channel++; + } } void pwmout_period_ms(pwmout_t *obj, int ms) @@ -202,20 +339,20 @@ void pwmout_pulsewidth(pwmout_t *obj, float seconds) { - obj->width_cycles = (uint32_t) (((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div)) * seconds); - TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles); + uint16_t width_cycles = (uint16_t) (((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div)) * seconds); + TIMER_CompareBufSet(PWM_TIMER, obj->channel, width_cycles); } void pwmout_pulsewidth_ms(pwmout_t *obj, int ms) { - obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * ms) / 1000; - TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles); + uint16_t width_cycles = (uint16_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * ms) / 1000; + TIMER_CompareBufSet(PWM_TIMER, obj->channel, width_cycles); } void pwmout_pulsewidth_us(pwmout_t *obj, int us) { - obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * us) / 1000000; - TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles); + uint16_t width_cycles = (uint16_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * us) / 1000000; + TIMER_CompareBufSet(PWM_TIMER, obj->channel, width_cycles); } #endif