Diff: pwmout_api.c

Revision:

0:e4d670b91a9a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pwmout_api.c	Wed Mar 23 21:26:50 2016 +0000
@@ -0,0 +1,135 @@
+/* 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"
+
+#if DEVICE_PWMOUT
+
+#include "cmsis.h"
+#include "pinmap.h"
+#include "fsl_ftm_hal.h"
+#include "fsl_mcg_hal.h"
+#include "fsl_clock_manager.h"
+#include "PeripheralPins.h"
+
+static float pwm_clock_mhz;
+
+void pwmout_init(pwmout_t* obj, PinName pin) {
+    PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
+    MBED_ASSERT(pwm != (PWMName)NC);
+
+    obj->pwm_name = pwm;
+
+    uint32_t pwm_base_clock;
+    CLOCK_SYS_GetFreq(kBusClock, &pwm_base_clock);
+    float clkval = (float)pwm_base_clock / 1000000.0f;
+    uint32_t clkdiv = 0;
+    while (clkval > 1) {
+        clkdiv++;
+        clkval /= 2.0f;
+        if (clkdiv == 7) {
+            break;
+        }
+    }
+
+    pwm_clock_mhz = clkval;
+    uint32_t channel = pwm & 0xF;
+    uint32_t instance = pwm >> TPM_SHIFT;
+    uint32_t ftm_addrs[] = FTM_BASE_ADDRS;
+    CLOCK_SYS_EnableFtmClock(instance);
+
+    FTM_HAL_SetTofFreq(ftm_addrs[instance], 3);
+    FTM_HAL_SetClockSource(ftm_addrs[instance], kClock_source_FTM_SystemClk);
+    FTM_HAL_SetClockPs(ftm_addrs[instance], (ftm_clock_ps_t)clkdiv);
+    FTM_HAL_SetCounter(ftm_addrs[instance], 0);
+    // default to 20ms: standard for servos, and fine for e.g. brightness control
+    pwmout_period_ms(obj, 20);
+    pwmout_write    (obj, 0);
+    ftm_pwm_param_t config = {
+        .mode = kFtmEdgeAlignedPWM,
+        .edgeMode = kFtmHighTrue
+    };
+    FTM_HAL_EnablePwmMode(ftm_addrs[instance], &config, channel);
+
+    // Wire pinout
+    pinmap_pinout(pin, PinMap_PWM);
+}
+
+void pwmout_free(pwmout_t* obj) {
+}
+
+void pwmout_write(pwmout_t* obj, float value) {
+    uint32_t instance = obj->pwm_name >> TPM_SHIFT;
+    if (value < 0.0f) {
+        value = 0.0f;
+    } else if (value > 1.0f) {
+        value = 1.0f;
+    }
+    uint32_t ftm_addrs[] = FTM_BASE_ADDRS;
+    uint16_t mod = FTM_HAL_GetMod(ftm_addrs[instance]);
+    uint32_t new_count = (uint32_t)((float)(mod) * value);
+    // Stop FTM clock to ensure instant update of MOD register
+    FTM_HAL_SetClockSource(ftm_addrs[instance], kClock_source_FTM_None);
+    FTM_HAL_SetChnCountVal(ftm_addrs[instance], obj->pwm_name & 0xF, new_count);
+    FTM_HAL_SetCounter(ftm_addrs[instance], 0);
+    FTM_HAL_SetClockSource(ftm_addrs[instance], kClock_source_FTM_SystemClk);
+}
+
+float pwmout_read(pwmout_t* obj) {
+    uint32_t ftm_addrs[] = FTM_BASE_ADDRS;
+    uint16_t count = FTM_HAL_GetChnCountVal(ftm_addrs[obj->pwm_name >> TPM_SHIFT], obj->pwm_name & 0xF, 0);
+    uint16_t mod = FTM_HAL_GetMod(ftm_addrs[obj->pwm_name >> TPM_SHIFT]);
+    if (mod == 0)
+        return 0.0;
+    float v = (float)(count) / (float)(mod);
+    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) {
+    uint32_t instance = obj->pwm_name >> TPM_SHIFT;
+    uint32_t ftm_addrs[] = FTM_BASE_ADDRS;
+    float dc = pwmout_read(obj);
+    // Stop FTM clock to ensure instant update of MOD register
+    FTM_HAL_SetClockSource(ftm_addrs[instance], kClock_source_FTM_None);
+    FTM_HAL_SetMod(ftm_addrs[instance], (uint32_t)(pwm_clock_mhz * (float)us) - 1);
+    pwmout_write(obj, dc);
+    FTM_HAL_SetClockSource(ftm_addrs[instance], kClock_source_FTM_SystemClk);
+}
+
+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) {
+    uint32_t ftm_addrs[] = FTM_BASE_ADDRS;
+    uint32_t value = (uint32_t)(pwm_clock_mhz * (float)us);
+    FTM_HAL_SetChnCountVal(ftm_addrs[obj->pwm_name >> TPM_SHIFT], obj->pwm_name & 0xF, value);
+}
+
+#endif