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