Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
Child:
50:a417edff4437
Initial commit on mbed-dev



Replaces mbed-src (now inactive)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 0:9b334a45a8ff 1 /***************************************************************************//**
bogdanm 0:9b334a45a8ff 2 * @file pwmout_api.c
bogdanm 0:9b334a45a8ff 3 *******************************************************************************
bogdanm 0:9b334a45a8ff 4 * @section License
bogdanm 0:9b334a45a8ff 5 * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
bogdanm 0:9b334a45a8ff 6 *******************************************************************************
bogdanm 0:9b334a45a8ff 7 *
bogdanm 0:9b334a45a8ff 8 * Permission is granted to anyone to use this software for any purpose,
bogdanm 0:9b334a45a8ff 9 * including commercial applications, and to alter it and redistribute it
bogdanm 0:9b334a45a8ff 10 * freely, subject to the following restrictions:
bogdanm 0:9b334a45a8ff 11 *
bogdanm 0:9b334a45a8ff 12 * 1. The origin of this software must not be misrepresented; you must not
bogdanm 0:9b334a45a8ff 13 * claim that you wrote the original software.
bogdanm 0:9b334a45a8ff 14 * 2. Altered source versions must be plainly marked as such, and must not be
bogdanm 0:9b334a45a8ff 15 * misrepresented as being the original software.
bogdanm 0:9b334a45a8ff 16 * 3. This notice may not be removed or altered from any source distribution.
bogdanm 0:9b334a45a8ff 17 *
bogdanm 0:9b334a45a8ff 18 * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
bogdanm 0:9b334a45a8ff 19 * obligation to support this Software. Silicon Labs is providing the
bogdanm 0:9b334a45a8ff 20 * Software "AS IS", with no express or implied warranties of any kind,
bogdanm 0:9b334a45a8ff 21 * including, but not limited to, any implied warranties of merchantability
bogdanm 0:9b334a45a8ff 22 * or fitness for any particular purpose or warranties against infringement
bogdanm 0:9b334a45a8ff 23 * of any proprietary rights of a third party.
bogdanm 0:9b334a45a8ff 24 *
bogdanm 0:9b334a45a8ff 25 * Silicon Labs will not be liable for any consequential, incidental, or
bogdanm 0:9b334a45a8ff 26 * special damages, or any other relief, or for any claim by any third party,
bogdanm 0:9b334a45a8ff 27 * arising from your use of this Software.
bogdanm 0:9b334a45a8ff 28 *
bogdanm 0:9b334a45a8ff 29 ******************************************************************************/
bogdanm 0:9b334a45a8ff 30
bogdanm 0:9b334a45a8ff 31 #include "device.h"
bogdanm 0:9b334a45a8ff 32 #include "clocking.h"
bogdanm 0:9b334a45a8ff 33 #if DEVICE_PWMOUT
bogdanm 0:9b334a45a8ff 34
bogdanm 0:9b334a45a8ff 35 #include "mbed_assert.h"
bogdanm 0:9b334a45a8ff 36 #include "pwmout_api.h"
bogdanm 0:9b334a45a8ff 37 #include "cmsis.h"
bogdanm 0:9b334a45a8ff 38 #include "pinmap.h"
bogdanm 0:9b334a45a8ff 39 #include "PeripheralPins.h"
bogdanm 0:9b334a45a8ff 40 #include "device_peripherals.h"
bogdanm 0:9b334a45a8ff 41 #include "sleepmodes.h"
bogdanm 0:9b334a45a8ff 42
bogdanm 0:9b334a45a8ff 43 #include "em_cmu.h"
bogdanm 0:9b334a45a8ff 44 #include "em_gpio.h"
bogdanm 0:9b334a45a8ff 45 #include "em_timer.h"
bogdanm 0:9b334a45a8ff 46
bogdanm 0:9b334a45a8ff 47 static int pwm_prescaler_div;
bogdanm 0:9b334a45a8ff 48
bogdanm 0:9b334a45a8ff 49 uint32_t pwmout_get_channel_route(pwmout_t *obj)
bogdanm 0:9b334a45a8ff 50 {
bogdanm 0:9b334a45a8ff 51 MBED_ASSERT(obj->channel != (PWMName) NC);
bogdanm 0:9b334a45a8ff 52
bogdanm 0:9b334a45a8ff 53 switch (obj->channel) {
bogdanm 0:9b334a45a8ff 54 case PWM_CH0:
bogdanm 0:9b334a45a8ff 55 return TIMER_ROUTE_CC0PEN;
bogdanm 0:9b334a45a8ff 56 break;
bogdanm 0:9b334a45a8ff 57 case PWM_CH1:
bogdanm 0:9b334a45a8ff 58 return TIMER_ROUTE_CC1PEN;
bogdanm 0:9b334a45a8ff 59 break;
bogdanm 0:9b334a45a8ff 60 case PWM_CH2:
bogdanm 0:9b334a45a8ff 61 return TIMER_ROUTE_CC2PEN;
bogdanm 0:9b334a45a8ff 62 break;
bogdanm 0:9b334a45a8ff 63 default:
bogdanm 0:9b334a45a8ff 64 return 0;
bogdanm 0:9b334a45a8ff 65 }
bogdanm 0:9b334a45a8ff 66 }
bogdanm 0:9b334a45a8ff 67
bogdanm 0:9b334a45a8ff 68 void pwmout_enable_pins(pwmout_t *obj, uint8_t enable)
bogdanm 0:9b334a45a8ff 69 {
bogdanm 0:9b334a45a8ff 70 if (enable) {
bogdanm 0:9b334a45a8ff 71 pin_mode(obj->pin, PushPull);
bogdanm 0:9b334a45a8ff 72 } else {
bogdanm 0:9b334a45a8ff 73 // TODO_LP return PinMode to the previous state
bogdanm 0:9b334a45a8ff 74 pin_mode(obj->pin, Disabled);
bogdanm 0:9b334a45a8ff 75 }
bogdanm 0:9b334a45a8ff 76 }
bogdanm 0:9b334a45a8ff 77
bogdanm 0:9b334a45a8ff 78 void pwmout_enable(pwmout_t *obj, uint8_t enable)
bogdanm 0:9b334a45a8ff 79 {
bogdanm 0:9b334a45a8ff 80 /* Start with default CC (Compare/Capture) channel parameters */
bogdanm 0:9b334a45a8ff 81 TIMER_InitCC_TypeDef timerCCInit = TIMER_INITCC_DEFAULT;
bogdanm 0:9b334a45a8ff 82 if (enable) {
bogdanm 0:9b334a45a8ff 83 /* Set mode to PWM */
bogdanm 0:9b334a45a8ff 84 timerCCInit.mode = timerCCModePWM;
bogdanm 0:9b334a45a8ff 85 }
bogdanm 0:9b334a45a8ff 86
bogdanm 0:9b334a45a8ff 87 /* Configure CC channel */
bogdanm 0:9b334a45a8ff 88 TIMER_InitCC(PWM_TIMER, obj->channel, &timerCCInit);
bogdanm 0:9b334a45a8ff 89 }
bogdanm 0:9b334a45a8ff 90
bogdanm 0:9b334a45a8ff 91 void pwmout_init(pwmout_t *obj, PinName pin)
bogdanm 0:9b334a45a8ff 92 {
bogdanm 0:9b334a45a8ff 93 obj->channel = (PWMName) pinmap_peripheral(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 94 obj->pin = pin;
bogdanm 0:9b334a45a8ff 95 MBED_ASSERT(obj->channel != (PWMName) NC);
bogdanm 0:9b334a45a8ff 96
bogdanm 0:9b334a45a8ff 97 /* Turn on clock */
bogdanm 0:9b334a45a8ff 98 CMU_ClockEnable(PWM_TIMER_CLOCK, true);
bogdanm 0:9b334a45a8ff 99
bogdanm 0:9b334a45a8ff 100 /* Turn on timer */
bogdanm 0:9b334a45a8ff 101 if(!(PWM_TIMER->STATUS & TIMER_STATUS_RUNNING)) {
bogdanm 0:9b334a45a8ff 102 TIMER_Init_TypeDef timerInit = TIMER_INIT_DEFAULT;
bogdanm 0:9b334a45a8ff 103 TIMER_Init(PWM_TIMER, &timerInit);
bogdanm 0:9b334a45a8ff 104 }
bogdanm 0:9b334a45a8ff 105
bogdanm 0:9b334a45a8ff 106 /* Enable correct channel */
bogdanm 0:9b334a45a8ff 107 uint32_t routeloc = pwmout_get_channel_route(obj);
bogdanm 0:9b334a45a8ff 108 if(PWM_TIMER->ROUTE & routeloc) {
bogdanm 0:9b334a45a8ff 109 //This channel was already in use
bogdanm 0:9b334a45a8ff 110 //TODO: gracefully handle this case
bogdanm 0:9b334a45a8ff 111 } else {
bogdanm 0:9b334a45a8ff 112 //This channel was unused up to now
bogdanm 0:9b334a45a8ff 113 PWM_TIMER->ROUTE |= routeloc;
bogdanm 0:9b334a45a8ff 114 blockSleepMode(EM1);
bogdanm 0:9b334a45a8ff 115
bogdanm 0:9b334a45a8ff 116 //TODO: check if any channel was up already, then don't re-init timer
bogdanm 0:9b334a45a8ff 117 pwmout_enable(obj, true);
bogdanm 0:9b334a45a8ff 118 pwmout_enable_pins(obj, true);
bogdanm 0:9b334a45a8ff 119 }
bogdanm 0:9b334a45a8ff 120
bogdanm 0:9b334a45a8ff 121 /* Route correct channel to location 1 */
bogdanm 0:9b334a45a8ff 122 PWM_TIMER->ROUTE &= ~_TIMER_ROUTE_LOCATION_MASK;
bogdanm 0:9b334a45a8ff 123 PWM_TIMER->ROUTE |= PWM_ROUTE;
bogdanm 0:9b334a45a8ff 124
bogdanm 0:9b334a45a8ff 125 /* Set default 20ms frequency and 0ms pulse width */
bogdanm 0:9b334a45a8ff 126 pwmout_period(obj, 0.02);
bogdanm 0:9b334a45a8ff 127 }
bogdanm 0:9b334a45a8ff 128
bogdanm 0:9b334a45a8ff 129 void pwmout_free(pwmout_t *obj)
bogdanm 0:9b334a45a8ff 130 {
bogdanm 0:9b334a45a8ff 131 uint32_t routeloc = pwmout_get_channel_route(obj);
bogdanm 0:9b334a45a8ff 132 if(PWM_TIMER->ROUTE & routeloc) {
bogdanm 0:9b334a45a8ff 133 //This channel was in use, so disable
bogdanm 0:9b334a45a8ff 134 PWM_TIMER->ROUTE &= ~routeloc;
bogdanm 0:9b334a45a8ff 135 pwmout_enable_pins(obj, false);
bogdanm 0:9b334a45a8ff 136 unblockSleepMode(EM1);
bogdanm 0:9b334a45a8ff 137
bogdanm 0:9b334a45a8ff 138 //TODO: check if all channels are down, then switch off timer
bogdanm 0:9b334a45a8ff 139 } else {
bogdanm 0:9b334a45a8ff 140 //This channel was disabled already
bogdanm 0:9b334a45a8ff 141 }
bogdanm 0:9b334a45a8ff 142 }
bogdanm 0:9b334a45a8ff 143
bogdanm 0:9b334a45a8ff 144 void pwmout_write(pwmout_t *obj, float value)
bogdanm 0:9b334a45a8ff 145 {
bogdanm 0:9b334a45a8ff 146 if (value < 0.0f) {
bogdanm 0:9b334a45a8ff 147 value = 0;
bogdanm 0:9b334a45a8ff 148 } else if (value > 1.0f) {
bogdanm 0:9b334a45a8ff 149 value = 1;
bogdanm 0:9b334a45a8ff 150 }
bogdanm 0:9b334a45a8ff 151
bogdanm 0:9b334a45a8ff 152 float pulse_period_in_s = obj->period_cycles / ((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div));
bogdanm 0:9b334a45a8ff 153 pwmout_pulsewidth(obj, value * pulse_period_in_s);
bogdanm 0:9b334a45a8ff 154 }
bogdanm 0:9b334a45a8ff 155
bogdanm 0:9b334a45a8ff 156 float pwmout_read(pwmout_t *obj)
bogdanm 0:9b334a45a8ff 157 {
bogdanm 0:9b334a45a8ff 158 return obj->width_cycles / (float) obj->period_cycles;
bogdanm 0:9b334a45a8ff 159 }
bogdanm 0:9b334a45a8ff 160
bogdanm 0:9b334a45a8ff 161 // Set the PWM period, keeping the absolute pulse width the same.
bogdanm 0:9b334a45a8ff 162 void pwmout_period(pwmout_t *obj, float seconds)
bogdanm 0:9b334a45a8ff 163 {
bogdanm 0:9b334a45a8ff 164 // Find the lowest prescaler divider possible.
bogdanm 0:9b334a45a8ff 165 // This gives us max resolution for a given period
bogdanm 0:9b334a45a8ff 166
bogdanm 0:9b334a45a8ff 167 //The value of the top register if prescaler is set to 0
bogdanm 0:9b334a45a8ff 168 int cycles = REFERENCE_FREQUENCY * seconds;
bogdanm 0:9b334a45a8ff 169 pwm_prescaler_div = 0;
bogdanm 0:9b334a45a8ff 170
bogdanm 0:9b334a45a8ff 171 //The top register is only 16 bits, so we keep dividing till we are below 0xFFFF
bogdanm 0:9b334a45a8ff 172 while (cycles > 0xFFFF) {
bogdanm 0:9b334a45a8ff 173 cycles /= 2;
bogdanm 0:9b334a45a8ff 174 pwm_prescaler_div++;
bogdanm 0:9b334a45a8ff 175
bogdanm 0:9b334a45a8ff 176 //Max pwm_prescaler_div supported is 10
bogdanm 0:9b334a45a8ff 177 if (pwm_prescaler_div > 10) {
bogdanm 0:9b334a45a8ff 178 pwm_prescaler_div = 10;
bogdanm 0:9b334a45a8ff 179 cycles = 0xFFFF; //Set it to max possible value;
bogdanm 0:9b334a45a8ff 180 break;
bogdanm 0:9b334a45a8ff 181 }
bogdanm 0:9b334a45a8ff 182 }
bogdanm 0:9b334a45a8ff 183
bogdanm 0:9b334a45a8ff 184 obj->period_cycles = cycles;
bogdanm 0:9b334a45a8ff 185
bogdanm 0:9b334a45a8ff 186 //Set prescaler
bogdanm 0:9b334a45a8ff 187 PWM_TIMER->CTRL = (PWM_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (pwm_prescaler_div << _TIMER_CTRL_PRESC_SHIFT);
bogdanm 0:9b334a45a8ff 188
bogdanm 0:9b334a45a8ff 189 /* Set Top Value, which controls the PWM period */
bogdanm 0:9b334a45a8ff 190 TIMER_TopSet(PWM_TIMER, obj->period_cycles);
bogdanm 0:9b334a45a8ff 191 }
bogdanm 0:9b334a45a8ff 192
bogdanm 0:9b334a45a8ff 193 void pwmout_period_ms(pwmout_t *obj, int ms)
bogdanm 0:9b334a45a8ff 194 {
bogdanm 0:9b334a45a8ff 195 pwmout_period(obj, ms / 1000.0f);
bogdanm 0:9b334a45a8ff 196 }
bogdanm 0:9b334a45a8ff 197
bogdanm 0:9b334a45a8ff 198 void pwmout_period_us(pwmout_t *obj, int us)
bogdanm 0:9b334a45a8ff 199 {
bogdanm 0:9b334a45a8ff 200 pwmout_period(obj, us / 1000000.0f);
bogdanm 0:9b334a45a8ff 201 }
bogdanm 0:9b334a45a8ff 202
bogdanm 0:9b334a45a8ff 203 void pwmout_pulsewidth(pwmout_t *obj, float seconds)
bogdanm 0:9b334a45a8ff 204 {
bogdanm 0:9b334a45a8ff 205 obj->width_cycles = (uint32_t) (((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div)) * seconds);
bogdanm 0:9b334a45a8ff 206 TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
bogdanm 0:9b334a45a8ff 207 }
bogdanm 0:9b334a45a8ff 208
bogdanm 0:9b334a45a8ff 209 void pwmout_pulsewidth_ms(pwmout_t *obj, int ms)
bogdanm 0:9b334a45a8ff 210 {
bogdanm 0:9b334a45a8ff 211 obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * ms) / 1000;
bogdanm 0:9b334a45a8ff 212 TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
bogdanm 0:9b334a45a8ff 213 }
bogdanm 0:9b334a45a8ff 214
bogdanm 0:9b334a45a8ff 215 void pwmout_pulsewidth_us(pwmout_t *obj, int us)
bogdanm 0:9b334a45a8ff 216 {
bogdanm 0:9b334a45a8ff 217 obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * us) / 1000000;
bogdanm 0:9b334a45a8ff 218 TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
bogdanm 0:9b334a45a8ff 219 }
bogdanm 0:9b334a45a8ff 220
bogdanm 0:9b334a45a8ff 221 #endif