Mouse code for the MacroRat
Diff: mbed-dev/targets/TARGET_NXP/TARGET_LPC11UXX/pwmout_api.c
- Revision:
- 18:6a4db94011d3
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-dev/targets/TARGET_NXP/TARGET_LPC11UXX/pwmout_api.c Sun May 14 23:18:57 2017 +0000 @@ -0,0 +1,157 @@ +/* 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" +#include "PeripheralPins.h" // For the Peripheral to Pin Definitions found in the individual Target's Platform + +#define TCR_CNT_EN 0x00000001 +#define TCR_RESET 0x00000002 + +typedef struct { + uint8_t timer; + uint8_t mr; +} timer_mr; + +static timer_mr pwm_timer_map[11] = { + {0, 0}, {0, 1}, {0, 2}, + {1, 0}, {1, 1}, + {2, 0}, {2, 1}, {2, 2}, + {3, 0}, {3, 1}, {3, 2}, +}; + +static LPC_CTxxBx_Type *Timers[4] = { + LPC_CT16B0, LPC_CT16B1, + LPC_CT32B0, LPC_CT32B1 +}; + +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_CTxxBx_Type *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; + + // 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_CTxxBx_Type *timer = Timers[tid.timer]; + uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value); + + timer->MR[tid.mr] = t_off; +} + +float pwmout_read(pwmout_t* obj) { + timer_mr tid = pwm_timer_map[obj->pwm]; + LPC_CTxxBx_Type *timer = Timers[tid.timer]; + + float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3); + 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 = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000); + + timer_mr tid = pwm_timer_map[obj->pwm]; + LPC_CTxxBx_Type *timer = Timers[tid.timer]; + uint32_t old_period_ticks = timer->MR3; + + // for 16bit timer, set prescaler to avoid overflow + if (timer == LPC_CT16B0 || timer == LPC_CT16B1) { + uint16_t high_period_ticks = period_ticks >> 16; + timer->PR = high_period_ticks; + period_ticks /= (high_period_ticks + 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_CTxxBx_Type *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); + t_on = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000 / (timer->PR + 1)); + } + uint32_t t_off = timer->MR3 - t_on; + timer->MR[tid.mr] = t_off; + timer->TCR = TCR_CNT_EN; +}