Lee Kai Xuan
mbed-os
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erkin yucel
Diff: targets/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c
- Revision:
- 0:f269e3021894
diff -r 000000000000 -r f269e3021894 targets/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,202 @@
+/* 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"
+
+static LPC_SCT0_Type *SCTs[4] = {
+ (LPC_SCT0_Type*)LPC_SCT0,
+ (LPC_SCT0_Type*)LPC_SCT1,
+ (LPC_SCT0_Type*)LPC_SCT2,
+ (LPC_SCT0_Type*)LPC_SCT3,
+};
+
+// bit flags for used SCTs
+static unsigned char sct_used = (1 << 3);
+static int get_available_sct(void) {
+ 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 != (uint32_t)NC);
+
+ int sct_n = get_available_sct();
+ if (sct_n == -1) {
+ error("No available SCT");
+ }
+
+ sct_used |= (1 << sct_n);
+ obj->pwm = SCTs[sct_n];
+ obj->pwm_ch = sct_n;
+
+ LPC_SCT0_Type* pwm = obj->pwm;
+
+ // Enable the SCT clock
+ LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << (obj->pwm_ch + 2));
+
+ // Clear peripheral reset the SCT:
+ LPC_SYSCON->PRESETCTRL1 |= (1 << (obj->pwm_ch + 2));
+ LPC_SYSCON->PRESETCTRL1 &= ~(1 << (obj->pwm_ch + 2));
+
+ switch(obj->pwm_ch) {
+ case 0:
+ // SCT0_OUT0
+ LPC_SWM->PINASSIGN[7] &= ~0x0000FF00;
+ LPC_SWM->PINASSIGN[7] |= (pin << 8);
+ break;
+ case 1:
+ // SCT1_OUT0
+ LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
+ LPC_SWM->PINASSIGN[8] |= (pin);
+ break;
+ case 2:
+ // SCT2_OUT0
+ LPC_SWM->PINASSIGN[8] &= ~0xFF000000;
+ LPC_SWM->PINASSIGN[8] |= (pin << 24);
+ break;
+ case 3:
+ // SCT3_OUT0
+ LPC_SWM->PINASSIGN[9] &= ~0x00FF0000;
+ LPC_SWM->PINASSIGN[9] |= (pin << 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);
+
+ pwm->OUT0_SET = (1 << 0); // event 0
+ pwm->OUT0_CLR = (1 << 1); // event 1
+
+ pwm->EV0_CTRL = (1 << 12);
+ pwm->EV0_STATE = 0xFFFFFFFF;
+ pwm->EV1_CTRL = (1 << 12) | (1 << 0);
+ pwm->EV1_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->SYSAHBCLKCTRL1 &= ~(1 << (obj->pwm_ch + 2));
+ sct_used &= ~(1 << obj->pwm_ch);
+}
+
+void pwmout_write(pwmout_t* obj, float value) {
+ LPC_SCT0_Type* pwm = obj->pwm;
+ if (value < 0.0f) {
+ value = 0.0;
+ } else if (value > 1.0f) {
+ value = 1.0;
+ }
+ uint32_t t_on = (uint32_t)((float)(pwm->MATCHREL0 + 1) * value);
+ if (t_on > 0) {
+ pwm->MATCHREL1 = t_on - 1;
+
+ // Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
+ if (pwm->CTRL & (1 << 2)) {
+ pwm->MATCH1 = pwm->MATCHREL1;
+ pwm->CTRL &= ~(1 << 2);
+ }
+ } else {
+ // Halt the timer and force the output low
+ pwm->CTRL |= (1 << 2) | (1 << 3);
+ pwm->OUTPUT = 0x00000000;
+ }
+}
+
+float pwmout_read(pwmout_t* obj) {
+ LPC_SCT0_Type* pwm = obj->pwm;
+ uint32_t t_off = pwm->MATCHREL0 + 1;
+ uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
+ 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) {
+ LPC_SCT0_Type* pwm = obj->pwm;
+ uint32_t t_off = pwm->MATCHREL0 + 1;
+ uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
+ float v = (float)t_on/(float)t_off;
+ uint32_t period_ticks = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
+ uint32_t pulsewidth_ticks = period_ticks * v;
+ pwm->MATCHREL0 = period_ticks - 1;
+ if (pulsewidth_ticks > 0) {
+ pwm->MATCHREL1 = pulsewidth_ticks - 1;
+
+ // Un-halt the timer and ensure the new period & pulse-width take immediate effect if necessary
+ if (pwm->CTRL & (1 << 2)) {
+ pwm->MATCH0 = pwm->MATCHREL0;
+ pwm->MATCH1 = pwm->MATCHREL1;
+ pwm->CTRL &= ~(1 << 2);
+ }
+ } else {
+ // Halt the timer and force the output low
+ pwm->CTRL |= (1 << 2) | (1 << 3);
+ pwm->OUTPUT = 0x00000000;
+
+ // Ensure the new period will take immediate effect when the timer is un-halted
+ pwm->MATCH0 = pwm->MATCHREL0;
+ }
+}
+
+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) {
+ LPC_SCT0_Type* pwm = obj->pwm;
+ if (us > 0) {
+ pwm->MATCHREL1 = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000) - 1;
+
+ // Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
+ if (pwm->CTRL & (1 << 2)) {
+ pwm->MATCH1 = pwm->MATCHREL1;
+ pwm->CTRL &= ~(1 << 2);
+ }
+ } else {
+ // Halt the timer and force the output low
+ pwm->CTRL |= (1 << 2) | (1 << 3);
+ pwm->OUTPUT = 0x00000000;
+ }
+}
+