--- /dev/null
+/* 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;
+}