Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_MCU_K64F/pwmout_api.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 17 #include "pwmout_api.h"
<> 144:ef7eb2e8f9f7 18
<> 144:ef7eb2e8f9f7 19 #if DEVICE_PWMOUT
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 22 #include "pinmap.h"
<> 144:ef7eb2e8f9f7 23 #include "fsl_ftm.h"
<> 144:ef7eb2e8f9f7 24 #include "PeripheralPins.h"
<> 144:ef7eb2e8f9f7 25
<> 144:ef7eb2e8f9f7 26 static float pwm_clock_mhz;
<> 144:ef7eb2e8f9f7 27 /* Array of FTM peripheral base address. */
<> 144:ef7eb2e8f9f7 28 static FTM_Type *const ftm_addrs[] = FTM_BASE_PTRS;
<> 144:ef7eb2e8f9f7 29
<> 144:ef7eb2e8f9f7 30 void pwmout_init(pwmout_t* obj, PinName pin) {
<> 144:ef7eb2e8f9f7 31 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 32 MBED_ASSERT(pwm != (PWMName)NC);
<> 144:ef7eb2e8f9f7 33
<> 144:ef7eb2e8f9f7 34 obj->pwm_name = pwm;
<> 144:ef7eb2e8f9f7 35
<> 144:ef7eb2e8f9f7 36 uint32_t pwm_base_clock;
<> 144:ef7eb2e8f9f7 37 pwm_base_clock = CLOCK_GetFreq(kCLOCK_BusClk);
<> 144:ef7eb2e8f9f7 38 float clkval = (float)pwm_base_clock / 1000000.0f;
<> 144:ef7eb2e8f9f7 39 uint32_t clkdiv = 0;
<> 144:ef7eb2e8f9f7 40 while (clkval > 1) {
<> 144:ef7eb2e8f9f7 41 clkdiv++;
<> 144:ef7eb2e8f9f7 42 clkval /= 2.0f;
<> 144:ef7eb2e8f9f7 43 if (clkdiv == 7) {
<> 144:ef7eb2e8f9f7 44 break;
<> 144:ef7eb2e8f9f7 45 }
<> 144:ef7eb2e8f9f7 46 }
<> 144:ef7eb2e8f9f7 47
<> 144:ef7eb2e8f9f7 48 pwm_clock_mhz = clkval;
<> 144:ef7eb2e8f9f7 49 uint32_t channel = pwm & 0xF;
<> 144:ef7eb2e8f9f7 50 uint32_t instance = pwm >> TPM_SHIFT;
<> 144:ef7eb2e8f9f7 51 ftm_config_t ftmInfo;
<> 144:ef7eb2e8f9f7 52
<> 144:ef7eb2e8f9f7 53 FTM_GetDefaultConfig(&ftmInfo);
<> 144:ef7eb2e8f9f7 54 ftmInfo.prescale = (ftm_clock_prescale_t)clkdiv;
<> 144:ef7eb2e8f9f7 55 /* Initialize FTM module */
<> 144:ef7eb2e8f9f7 56 FTM_Init(ftm_addrs[instance], &ftmInfo);
<> 144:ef7eb2e8f9f7 57
<> 144:ef7eb2e8f9f7 58 ftm_addrs[instance]->CONF |= FTM_CONF_NUMTOF(3);
<> 144:ef7eb2e8f9f7 59
<> 144:ef7eb2e8f9f7 60 ftm_chnl_pwm_signal_param_t config = {
<> 144:ef7eb2e8f9f7 61 .chnlNumber = (ftm_chnl_t)channel,
<> 144:ef7eb2e8f9f7 62 .level = kFTM_HighTrue,
<> 144:ef7eb2e8f9f7 63 .dutyCyclePercent = 0,
<> 144:ef7eb2e8f9f7 64 .firstEdgeDelayPercent = 0
<> 144:ef7eb2e8f9f7 65 };
<> 144:ef7eb2e8f9f7 66 // default to 20ms: standard for servos, and fine for e.g. brightness control
<> 144:ef7eb2e8f9f7 67 FTM_SetupPwm(ftm_addrs[instance], &config, 1, kFTM_EdgeAlignedPwm, 50, pwm_base_clock);
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 FTM_StartTimer(ftm_addrs[instance], kFTM_SystemClock);
<> 144:ef7eb2e8f9f7 70
<> 144:ef7eb2e8f9f7 71 // Wire pinout
<> 144:ef7eb2e8f9f7 72 pinmap_pinout(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 73 }
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 void pwmout_free(pwmout_t* obj) {
<> 144:ef7eb2e8f9f7 76 FTM_Deinit(ftm_addrs[obj->pwm_name >> TPM_SHIFT]);
<> 144:ef7eb2e8f9f7 77 }
<> 144:ef7eb2e8f9f7 78
<> 144:ef7eb2e8f9f7 79 void pwmout_write(pwmout_t* obj, float value) {
<> 144:ef7eb2e8f9f7 80 if (value < 0.0f) {
<> 144:ef7eb2e8f9f7 81 value = 0.0f;
<> 144:ef7eb2e8f9f7 82 } else if (value > 1.0f) {
<> 144:ef7eb2e8f9f7 83 value = 1.0f;
<> 144:ef7eb2e8f9f7 84 }
<> 144:ef7eb2e8f9f7 85
<> 144:ef7eb2e8f9f7 86 FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT];
<> 144:ef7eb2e8f9f7 87 uint16_t mod = base->MOD & FTM_MOD_MOD_MASK;
<> 144:ef7eb2e8f9f7 88 uint32_t new_count = (uint32_t)((float)(mod) * value);
<> 144:ef7eb2e8f9f7 89 // Update of CnV register
<> 144:ef7eb2e8f9f7 90 base->CONTROLS[obj->pwm_name & 0xF].CnV = new_count;
<> 144:ef7eb2e8f9f7 91 base->CNT = 0;
<> 144:ef7eb2e8f9f7 92 /* Software trigger to update registers */
<> 144:ef7eb2e8f9f7 93 FTM_SetSoftwareTrigger(base, true);
<> 144:ef7eb2e8f9f7 94 }
<> 144:ef7eb2e8f9f7 95
<> 144:ef7eb2e8f9f7 96 float pwmout_read(pwmout_t* obj) {
<> 144:ef7eb2e8f9f7 97 FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT];
<> 144:ef7eb2e8f9f7 98 uint16_t count = (base->CONTROLS[obj->pwm_name & 0xF].CnV) & FTM_CnV_VAL_MASK;
<> 144:ef7eb2e8f9f7 99 uint16_t mod = base->MOD & FTM_MOD_MOD_MASK;
<> 144:ef7eb2e8f9f7 100
<> 144:ef7eb2e8f9f7 101 if (mod == 0)
<> 144:ef7eb2e8f9f7 102 return 0.0;
<> 144:ef7eb2e8f9f7 103 float v = (float)(count) / (float)(mod);
<> 144:ef7eb2e8f9f7 104 return (v > 1.0f) ? (1.0f) : (v);
<> 144:ef7eb2e8f9f7 105 }
<> 144:ef7eb2e8f9f7 106
<> 144:ef7eb2e8f9f7 107 void pwmout_period(pwmout_t* obj, float seconds) {
<> 144:ef7eb2e8f9f7 108 pwmout_period_us(obj, seconds * 1000000.0f);
<> 144:ef7eb2e8f9f7 109 }
<> 144:ef7eb2e8f9f7 110
<> 144:ef7eb2e8f9f7 111 void pwmout_period_ms(pwmout_t* obj, int ms) {
<> 144:ef7eb2e8f9f7 112 pwmout_period_us(obj, ms * 1000);
<> 144:ef7eb2e8f9f7 113 }
<> 144:ef7eb2e8f9f7 114
<> 144:ef7eb2e8f9f7 115 // Set the PWM period, keeping the duty cycle the same.
<> 144:ef7eb2e8f9f7 116 void pwmout_period_us(pwmout_t* obj, int us) {
<> 144:ef7eb2e8f9f7 117 FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT];
<> 144:ef7eb2e8f9f7 118 float dc = pwmout_read(obj);
<> 144:ef7eb2e8f9f7 119
<> 144:ef7eb2e8f9f7 120 // Stop FTM clock to ensure instant update of MOD register
<> 144:ef7eb2e8f9f7 121 base->MOD = FTM_MOD_MOD((pwm_clock_mhz * (float)us) - 1);
<> 144:ef7eb2e8f9f7 122 pwmout_write(obj, dc);
<> 144:ef7eb2e8f9f7 123 }
<> 144:ef7eb2e8f9f7 124
<> 144:ef7eb2e8f9f7 125 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
<> 144:ef7eb2e8f9f7 126 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
<> 144:ef7eb2e8f9f7 127 }
<> 144:ef7eb2e8f9f7 128
<> 144:ef7eb2e8f9f7 129 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
<> 144:ef7eb2e8f9f7 130 pwmout_pulsewidth_us(obj, ms * 1000);
<> 144:ef7eb2e8f9f7 131 }
<> 144:ef7eb2e8f9f7 132
<> 144:ef7eb2e8f9f7 133 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
<> 144:ef7eb2e8f9f7 134 FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT];
<> 144:ef7eb2e8f9f7 135 uint32_t value = (uint32_t)(pwm_clock_mhz * (float)us);
<> 144:ef7eb2e8f9f7 136
<> 144:ef7eb2e8f9f7 137 // Update of CnV register
<> 144:ef7eb2e8f9f7 138 base->CONTROLS[obj->pwm_name & 0xF].CnV = value;
<> 144:ef7eb2e8f9f7 139 /* Software trigger to update registers */
<> 144:ef7eb2e8f9f7 140 FTM_SetSoftwareTrigger(base, true);
<> 144:ef7eb2e8f9f7 141 }
<> 144:ef7eb2e8f9f7 142
<> 144:ef7eb2e8f9f7 143 #endif