added prescaler for 16 bit pwm in LPC1347 target
Fork of mbed-dev by
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?
User | Revision | Line number | New 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 |