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targets/TARGET_NXP/TARGET_LPC23XX/pwmout_api.c
- Committer:
- amithy
- Date:
- 2017-11-09
- Revision:
- 178:c26431f84b0d
- Parent:
- 149:156823d33999
File content as of revision 178:c26431f84b0d:
/* 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" #include "cmsis.h" #include "pinmap.h" #define TCR_CNT_EN 0x00000001 #define TCR_RESET 0x00000002 // PORT ID, PWM ID, Pin function static const PinMap PinMap_PWM[] = { {P1_18, PWM_1, 2}, {P1_20, PWM_2, 2}, {P1_21, PWM_3, 2}, {P1_23, PWM_4, 2}, {P1_24, PWM_5, 2}, {P1_26, PWM_6, 2}, {P2_0 , PWM_1, 1}, {P2_1 , PWM_2, 1}, {P2_2 , PWM_3, 1}, {P2_3 , PWM_4, 1}, {P2_4 , PWM_5, 1}, {P2_5 , PWM_6, 1}, {P3_25, PWM_2, 3}, {P3_26, PWM_3, 3}, {NC, NC, 0} }; __IO uint32_t *PWM_MATCH[] = { &(LPC_PWM1->MR0), &(LPC_PWM1->MR1), &(LPC_PWM1->MR2), &(LPC_PWM1->MR3), &(LPC_PWM1->MR4), &(LPC_PWM1->MR5), &(LPC_PWM1->MR6) }; #define TCR_PWM_EN 0x00000008 static unsigned int pwm_clock_mhz; void pwmout_init(pwmout_t* obj, PinName pin) { // determine the channel PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM); MBED_ASSERT(pwm != (PWMName)NC); obj->pwm = pwm; obj->MR = PWM_MATCH[pwm]; // ensure the power is on LPC_SC->PCONP |= 1 << 6; // ensure clock to /4 LPC_SC->PCLKSEL0 &= ~(0x3 << 12); // pclk = /4 LPC_PWM1->PR = 0; // no pre-scale // ensure single PWM mode LPC_PWM1->MCR = 1 << 1; // reset TC on match 0 // enable the specific PWM output LPC_PWM1->PCR |= 1 << (8 + pwm); pwm_clock_mhz = SystemCoreClock / 4000000; // default to 20ms: standard for servos, and fine for e.g. brightness control pwmout_period_ms(obj, 20); pwmout_write (obj, 0); // Wire pinout pinmap_pinout(pin, PinMap_PWM); } void pwmout_free(pwmout_t* obj) { // [TODO] } void pwmout_write(pwmout_t* obj, float value) { if (value < 0.0f) { value = 0.0; } else if (value > 1.0f) { value = 1.0; } // set channel match to percentage uint32_t v = (uint32_t)((float)(LPC_PWM1->MR0) * value); // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout if (v == LPC_PWM1->MR0) { v++; } *obj->MR = v; // accept on next period start LPC_PWM1->LER |= 1 << obj->pwm; } float pwmout_read(pwmout_t* obj) { float v = (float)(*obj->MR) / (float)(LPC_PWM1->MR0); 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) { // calculate number of ticks uint32_t ticks = pwm_clock_mhz * us; // set reset LPC_PWM1->TCR = TCR_RESET; // set the global match register LPC_PWM1->MR0 = ticks; // Scale the pulse width to preserve the duty ratio if (LPC_PWM1->MR0 > 0) { *obj->MR = (*obj->MR * ticks) / LPC_PWM1->MR0; } // set the channel latch to update value at next period start LPC_PWM1->LER |= 1 << 0; // enable counter and pwm, clear reset LPC_PWM1->TCR = TCR_CNT_EN | TCR_PWM_EN; } 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) { // calculate number of ticks uint32_t v = pwm_clock_mhz * us; // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout if (v == LPC_PWM1->MR0) { v++; } // set the match register value *obj->MR = v; // set the channel latch to update value at next period start LPC_PWM1->LER |= 1 << obj->pwm; }