added prescaler for 16 bit pwm in LPC1347 target
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Diff: targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_K22F/pwmout_api.c
- Revision:
- 121:7f86b4238bec
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_K22F/pwmout_api.c Tue May 03 00:15:16 2016 +0100 @@ -0,0 +1,143 @@ +/* mbed Microcontroller Library + * Copyright (c) 2006-2013 ARM Limited + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +#include "mbed_assert.h" +#include "pwmout_api.h" + +#if DEVICE_PWMOUT + +#include "cmsis.h" +#include "pinmap.h" +#include "fsl_ftm.h" +#include "PeripheralPins.h" + +static float pwm_clock_mhz; +/* Array of FTM peripheral base address. */ +static FTM_Type *const ftm_addrs[] = FTM_BASE_PTRS; + +void pwmout_init(pwmout_t* obj, PinName pin) { + PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM); + MBED_ASSERT(pwm != (PWMName)NC); + + obj->pwm_name = pwm; + + uint32_t pwm_base_clock; + pwm_base_clock = CLOCK_GetFreq(kCLOCK_BusClk); + float clkval = (float)pwm_base_clock / 1000000.0f; + uint32_t clkdiv = 0; + while (clkval > 1) { + clkdiv++; + clkval /= 2.0f; + if (clkdiv == 7) { + break; + } + } + + pwm_clock_mhz = clkval; + uint32_t channel = pwm & 0xF; + uint32_t instance = pwm >> TPM_SHIFT; + ftm_config_t ftmInfo; + + FTM_GetDefaultConfig(&ftmInfo); + ftmInfo.prescale = (ftm_clock_prescale_t)clkdiv; + /* Initialize FTM module */ + FTM_Init(ftm_addrs[instance], &ftmInfo); + + ftm_addrs[instance]->CONF |= FTM_CONF_NUMTOF(3); + + ftm_chnl_pwm_signal_param_t config = { + .chnlNumber = (ftm_chnl_t)channel, + .level = kFTM_HighTrue, + .dutyCyclePercent = 0, + .firstEdgeDelayPercent = 0 + }; + // default to 20ms: standard for servos, and fine for e.g. brightness control + FTM_SetupPwm(ftm_addrs[instance], &config, 1, kFTM_EdgeAlignedPwm, 50, pwm_base_clock); + + FTM_StartTimer(ftm_addrs[instance], kFTM_SystemClock); + + // Wire pinout + pinmap_pinout(pin, PinMap_PWM); +} + +void pwmout_free(pwmout_t* obj) { + FTM_Deinit(ftm_addrs[obj->pwm_name >> TPM_SHIFT]); +} + +void pwmout_write(pwmout_t* obj, float value) { + if (value < 0.0f) { + value = 0.0f; + } else if (value > 1.0f) { + value = 1.0f; + } + + FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT]; + uint16_t mod = base->MOD & FTM_MOD_MOD_MASK; + uint32_t new_count = (uint32_t)((float)(mod) * value); + // Update of CnV register + base->CONTROLS[obj->pwm_name & 0xF].CnV = new_count; + base->CNT = 0; + /* Software trigger to update registers */ + FTM_SetSoftwareTrigger(base, true); +} + +float pwmout_read(pwmout_t* obj) { + FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT]; + uint16_t count = (base->CONTROLS[obj->pwm_name & 0xF].CnV) & FTM_CnV_VAL_MASK; + uint16_t mod = base->MOD & FTM_MOD_MOD_MASK; + + if (mod == 0) + return 0.0; + float v = (float)(count) / (float)(mod); + return (v > 1.0f) ? (1.0f) : (v); +} + +void pwmout_period(pwmout_t* obj, float seconds) { + pwmout_period_us(obj, seconds * 1000000.0f); +} + +void pwmout_period_ms(pwmout_t* obj, int ms) { + pwmout_period_us(obj, ms * 1000); +} + +// Set the PWM period, keeping the duty cycle the same. +void pwmout_period_us(pwmout_t* obj, int us) { + FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT]; + float dc = pwmout_read(obj); + + // Stop FTM clock to ensure instant update of MOD register + base->MOD = FTM_MOD_MOD((pwm_clock_mhz * (float)us) - 1); + pwmout_write(obj, dc); +} + +void pwmout_pulsewidth(pwmout_t* obj, float seconds) { + pwmout_pulsewidth_us(obj, seconds * 1000000.0f); +} + +void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) { + pwmout_pulsewidth_us(obj, ms * 1000); +} + +void pwmout_pulsewidth_us(pwmout_t* obj, int us) { + FTM_Type *base = ftm_addrs[obj->pwm_name >> TPM_SHIFT]; + uint32_t value = (uint32_t)(pwm_clock_mhz * (float)us); + + // Update of CnV register + base->CONTROLS[obj->pwm_name & 0xF].CnV = value; + /* Software trigger to update registers */ + FTM_SetSoftwareTrigger(base, true); +} + +#endif