added prescaler for 16 bit pwm in LPC1347 target
Fork of mbed-dev by
targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c
- Committer:
- mbed_official
- Date:
- 2016-01-15
- Revision:
- 50:a417edff4437
- Parent:
- 0:9b334a45a8ff
- Child:
- 144:ef7eb2e8f9f7
File content as of revision 50:a417edff4437:
/***************************************************************************//** * @file pwmout_api.c ******************************************************************************* * @section License * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b> ******************************************************************************* * * Permission is granted to anyone to use this software for any purpose, * including commercial applications, and to alter it and redistribute it * freely, subject to the following restrictions: * * 1. The origin of this software must not be misrepresented; you must not * claim that you wrote the original software. * 2. Altered source versions must be plainly marked as such, and must not be * misrepresented as being the original software. * 3. This notice may not be removed or altered from any source distribution. * * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no * obligation to support this Software. Silicon Labs is providing the * Software "AS IS", with no express or implied warranties of any kind, * including, but not limited to, any implied warranties of merchantability * or fitness for any particular purpose or warranties against infringement * of any proprietary rights of a third party. * * Silicon Labs will not be liable for any consequential, incidental, or * special damages, or any other relief, or for any claim by any third party, * arising from your use of this Software. * ******************************************************************************/ #include "device.h" #include "clocking.h" #if DEVICE_PWMOUT #include "mbed_assert.h" #include "pwmout_api.h" #include "cmsis.h" #include "pinmap.h" #include "PeripheralPins.h" #include "device_peripherals.h" #include "sleepmodes.h" #include "em_cmu.h" #include "em_gpio.h" #include "em_timer.h" static int pwm_prescaler_div; 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(channel != (PWMName) NC); 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; case PWM_CH1: return TIMER_ROUTE_CC1PEN; break; 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) { pin_mode(obj->pin, PushPull); } else { // TODO_LP return PinMode to the previous state pin_mode(obj->pin, Disabled); } } void pwmout_enable(pwmout_t *obj, uint8_t enable){ if (enable) { // 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; } } void pwmout_init(pwmout_t *obj, PinName pin) { obj->channel = (PWMName) pinmap_peripheral(pin, PinMap_PWM); obj->pin = pin; MBED_ASSERT(obj->channel != (PWMName) NC); /* Turn on clock */ CMU_ClockEnable(PWM_TIMER_CLOCK, true); /* Turn on timer */ if(!(PWM_TIMER->STATUS & TIMER_STATUS_RUNNING)) { TIMER_Init_TypeDef timerInit = TIMER_INIT_DEFAULT; TIMER_Init(PWM_TIMER, &timerInit); } // 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. mbed_error? return; } else { pwmout_set_channel_route(pwmout_get_channel_route(obj->channel)); blockSleepMode(EM1); pwmout_enable(obj, true); pwmout_enable_pins(obj, true); } // 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 pwmout_period(obj, 0.02); } void pwmout_free(pwmout_t *obj) { if(pwmout_disable_channel_route(pwmout_get_channel_route(obj->channel))) { //Channel was previously enabled, so do housekeeping unblockSleepMode(EM1); } 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) { width_cycles = 0; } else if (value >= 1.0f) { width_cycles = PWM_TIMER->TOPB + 1; } else { width_cycles = (uint16_t)((float)PWM_TIMER->TOPB * value); } TIMER_CompareBufSet(PWM_TIMER, channel, width_cycles); } float pwmout_read(pwmout_t *obj) { return pwmout_calculate_duty(TIMER_CaptureGet(PWM_TIMER, obj->channel), TIMER_TopGet(PWM_TIMER)); } 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. // This gives us max resolution for a given period //The value of the top register if prescaler is set to 0 int cycles = REFERENCE_FREQUENCY * seconds; pwm_prescaler_div = 0; //The top register is only 16 bits, so we keep dividing till we are below 0xFFFF while (cycles > 0xFFFF) { cycles /= 2; pwm_prescaler_div++; //Max pwm_prescaler_div supported is 10 if (pwm_prescaler_div > 10) { pwm_prescaler_div = 10; cycles = 0xFFFF; //Set it to max possible value; break; } } //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_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) { pwmout_period(obj, ms / 1000.0f); } void pwmout_period_us(pwmout_t *obj, int us) { pwmout_period(obj, us / 1000000.0f); } void pwmout_pulsewidth(pwmout_t *obj, float seconds) { 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) { 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) { uint16_t width_cycles = (uint16_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * us) / 1000000; TIMER_CompareBufSet(PWM_TIMER, obj->channel, width_cycles); } #endif