Gordon Craig
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Diff: targets/TARGET_NXP/TARGET_LPC82X/pwmout_api.c
- Revision:
- 149:156823d33999
- Parent:
- 144:ef7eb2e8f9f7
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC82X/pwmout_api.c Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,203 @@
+/* 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 "mbed_error.h"
+
+#if DEVICE_PWMOUT
+
+// bit flags for used SCTs
+static unsigned char sct_used = 0;
+
+static int get_available_sct()
+{
+ int i;
+ for (i = 0; i < 4; i++) {
+ if ((sct_used & (1 << i)) == 0)
+ return i;
+ }
+ return -1;
+}
+
+void pwmout_init(pwmout_t* obj, PinName pin)
+{
+ MBED_ASSERT(pin != (PinName)NC);
+
+ int sct_n = get_available_sct();
+ if (sct_n == -1) {
+ error("No available SCT");
+ }
+
+ sct_used |= (1 << sct_n);
+
+ obj->pwm = (LPC_SCT_Type*)LPC_SCT;
+ obj->pwm_ch = sct_n;
+
+ LPC_SCT_Type* pwm = obj->pwm;
+
+ // Enable the SCT clock
+ LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8);
+
+ // Clear peripheral reset the SCT:
+ LPC_SYSCON->PRESETCTRL |= (1 << 8);
+
+ switch(sct_n) {
+ case 0:
+ // SCT_OUT0
+ LPC_SWM->PINASSIGN[7] &= ~0xFF000000;
+ LPC_SWM->PINASSIGN[7] |= ((pin >> PIN_SHIFT) << 24);
+ break;
+ case 1:
+ // SCT_OUT1
+ LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
+ LPC_SWM->PINASSIGN[8] |= (pin >> PIN_SHIFT);
+ break;
+ case 2:
+ // SCT2_OUT2
+ LPC_SWM->PINASSIGN[8] &= ~0x0000FF00;
+ LPC_SWM->PINASSIGN[8] |= ((pin >> PIN_SHIFT) << 8);
+ break;
+ case 3:
+ // SCT3_OUT3
+ LPC_SWM->PINASSIGN[8] &= ~0x00FF0000;
+ LPC_SWM->PINASSIGN[8] |= ((pin >> PIN_SHIFT) << 16);
+ break;
+ default:
+ break;
+ }
+
+ // Unified 32-bit counter, autolimit
+ pwm->CONFIG |= ((0x3 << 17) | 0x01);
+
+ // halt and clear the counter
+ pwm->CTRL |= (1 << 2) | (1 << 3);
+
+ // System Clock -> us_ticker (1)MHz
+ pwm->CTRL &= ~(0x7F << 5);
+ pwm->CTRL |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5);
+
+ // Set event number
+ pwm->OUT[sct_n].SET = (1 << ((sct_n * 2) + 0));
+ pwm->OUT[sct_n].CLR = (1 << ((sct_n * 2) + 1));
+
+ pwm->EVENT[(sct_n * 2) + 0].CTRL = (1 << 12) | ((sct_n * 2) + 0); // match event
+ pwm->EVENT[(sct_n * 2) + 0].STATE = 0xFFFFFFFF;
+ pwm->EVENT[(sct_n * 2) + 1].CTRL = (1 << 12) | ((sct_n * 2) + 1);
+ pwm->EVENT[(sct_n * 2) + 1].STATE = 0xFFFFFFFF;
+
+ // default to 20ms: standard for servos, and fine for e.g. brightness control
+ pwmout_period_ms(obj, 20);
+ pwmout_write (obj, 0);
+}
+
+void pwmout_free(pwmout_t* obj)
+{
+ // Disable the SCT clock
+ LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 8);
+ sct_used &= ~(1 << obj->pwm_ch);
+}
+
+void pwmout_write(pwmout_t* obj, float value)
+{
+ if (value < 0.0f) {
+ value = 0.0;
+ } else if (value > 1.0f) {
+ value = 1.0f;
+ }
+ uint32_t t_on = (uint32_t)((float)(obj->pwm->MATCHREL[obj->pwm_ch * 2] + 1) * value);
+ if (t_on > 0) { // duty is not 0%
+ if (value != 1.0f) { // duty is not 100%
+ obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = t_on - 1;
+ // unhalt the counter
+ obj->pwm->CTRL &= ~(1 << 2);
+ } else { // duty is 100%
+ // halt and clear the counter
+ obj->pwm->CTRL |= (1 << 2) | (1 << 3);
+ // output level tied to high
+ obj->pwm->OUTPUT |= (1 << obj->pwm_ch);
+ }
+ } else { // duty is 0%
+ // halt and clear the counter
+ obj->pwm->CTRL |= (1 << 2) | (1 << 3);
+ // output level tied to low
+ obj->pwm->OUTPUT &= ~(1 << obj->pwm_ch);
+ }
+}
+
+float pwmout_read(pwmout_t* obj)
+{
+ uint32_t t_off = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0] + 1;
+ uint32_t t_on = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] + 1;
+ float v = (float)t_on/(float)t_off;
+ 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)
+{
+ // The period are off by one for MATCHREL, so +1 to get actual value
+ uint32_t t_off = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0] + 1;
+ uint32_t t_on = obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] + 1;
+ float v = (float)t_on/(float)t_off;
+ obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 0] = (uint32_t)us - 1;
+ if (us > 0) { // PWM period is not 0
+ obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = (uint32_t)((float)us * (float)v) - 1;
+ // unhalt the counter
+ obj->pwm->CTRL &= ~(1 << 2);
+ } else { // PWM period is 0
+ // halt and clear the counter
+ obj->pwm->CTRL |= (1 << 2) | (1 << 3);
+ // output level tied to low
+ obj->pwm->OUTPUT &= ~(1 << obj->pwm_ch);
+ }
+}
+
+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)
+{
+ if (us > 0) { // PWM peried is not 0
+ obj->pwm->MATCHREL[(obj->pwm_ch * 2) + 1] = (uint32_t)us - 1;
+ obj->pwm->CTRL &= ~(1 << 2);
+ } else { //PWM period is 0
+ // halt and clear the counter
+ obj->pwm->CTRL |= (1 << 2) | (1 << 3);
+ // output level tied to low
+ obj->pwm->OUTPUT &= ~(1 << obj->pwm_ch);
+ }
+}
+
+#endif