Mouse code for the MacroRat
mbed-dev/targets/TARGET_NXP/TARGET_LPC11XX_11CXX/pwmout_api.c
- Committer:
- sahilmgandhi
- Date:
- 2017-05-14
- Revision:
- 18:6a4db94011d3
File content as of revision 18:6a4db94011d3:
/* 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 /* To have a PWM where we can change both the period and the duty cycle, * we need an entire timer. With the following conventions: * * MR3 is used for the PWM period * * MR0, MR1, MR2 are used for the duty cycle */ static const PinMap PinMap_PWM[] = { /* CT16B0 */ {P0_8 , PWM_1, 0x02}, /* MR0 */ {P0_9 , PWM_2, 0x02}, /* MR1 */ /* CT16B1 */ {P1_9 , PWM_3, 0x01}, /* MR0 */ {P1_10, PWM_4, 0x02}, /* MR1 */ /* CT32B0 */ {P0_1 , PWM_5, 0x02}, /* MR2 */ {NC , NC ,0x00} }; typedef struct { uint8_t timer; uint8_t mr; } timer_mr; static timer_mr pwm_timer_map[5] = { {0, 0}, /* CT16B0, MR0 */ {0, 1}, /* CT16B0, MR1 */ {1, 0}, /* CT16B1, MR0 */ {1, 1}, /* CT16B1, MR1 */ {2, 2}, /* CT32B0, MR2 */ }; static LPC_TMR_TypeDef *Timers[3] = { LPC_TMR16B0, LPC_TMR16B1, LPC_TMR32B0 }; 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; // Timer registers timer_mr tid = pwm_timer_map[pwm]; LPC_TMR_TypeDef *timer = Timers[tid.timer]; // Disable timer timer->TCR = 0; // Power the correspondent timer LPC_SYSCON->SYSAHBCLKCTRL |= 1 << (tid.timer + 7); /* Enable PWM function */ timer->PWMC = (1 << 3)|(1 << 2)|(1 << 1)|(1 << 0); /* Reset Functionality on MR3 controlling the PWM period */ timer->MCR = 1 << 10; if (timer == LPC_TMR16B0 || timer == LPC_TMR16B1) { /* Set 16-bit timer prescaler to avoid timer expire for default 20ms */ /* This can be also modified by user application, but the prescaler value */ /* might be trade-off to timer accuracy */ timer->PR = 30; } // 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; } timer_mr tid = pwm_timer_map[obj->pwm]; LPC_TMR_TypeDef *timer = Timers[tid.timer]; uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value); // to avoid spike pulse when duty is 0% if (value == 0) { t_off++; } timer->TCR = TCR_RESET; timer->MR[tid.mr] = t_off; timer->TCR = TCR_CNT_EN; } float pwmout_read(pwmout_t* obj) { timer_mr tid = pwm_timer_map[obj->pwm]; LPC_TMR_TypeDef *timer = Timers[tid.timer]; float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3); if (timer->MR[tid.mr] > timer->MR3) { v = 0.0f; } 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) { int i = 0; uint32_t period_ticks; timer_mr tid = pwm_timer_map[obj->pwm]; LPC_TMR_TypeDef *timer = Timers[tid.timer]; uint32_t old_period_ticks = timer->MR3; period_ticks = (SystemCoreClock / 1000000 * us) / (timer->PR + 1); timer->TCR = TCR_RESET; timer->MR3 = period_ticks; // Scale the pulse width to preserve the duty ratio if (old_period_ticks > 0) { for (i=0; i<3; i++) { uint32_t t_off = period_ticks - (uint32_t)(((uint64_t)timer->MR[i] * (uint64_t)period_ticks) / (uint64_t)old_period_ticks); timer->MR[i] = t_off; } } timer->TCR = TCR_CNT_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) { timer_mr tid = pwm_timer_map[obj->pwm]; LPC_TMR_TypeDef *timer = Timers[tid.timer]; uint32_t t_on = (uint32_t)((((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000) / (timer->PR + 1)); timer->TCR = TCR_RESET; if (t_on > timer->MR3) { pwmout_period_us(obj, us); } uint32_t t_off = timer->MR3 - t_on; timer->MR[tid.mr] = t_off; timer->TCR = TCR_CNT_EN; }