added prescaler for 16 bit pwm in LPC1347 target
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targets/hal/TARGET_Freescale/TARGET_KSDK2_MCUS/TARGET_K22F/pwmout_api.c
- Committer:
- mbed_official
- Date:
- 2016-05-03
- Revision:
- 121:7f86b4238bec
File content as of revision 121:7f86b4238bec:
/* 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