Diff: targets/TARGET_Freescale/TARGET_K20XX/pwmout_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

Child:

151:5eaa88a5bcc7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_Freescale/TARGET_K20XX/pwmout_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,116 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2015 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"
+
+static float pwm_clock = 0;
+
+void pwmout_init(pwmout_t* obj, PinName pin) {
+    // determine the channel
+    PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
+    MBED_ASSERT(pwm != (PWMName)NC);
+
+    uint32_t clkdiv = 0;
+    float clkval = SystemCoreClock / 1000000.0f;
+
+    while (clkval > 1) {
+        clkdiv++;
+        clkval /= 2.0;
+        if (clkdiv == 7)
+            break;
+    }
+
+    pwm_clock = clkval;
+    unsigned int ftm_n = (pwm >> TPM_SHIFT);
+    unsigned int ch_n = (pwm & 0xFF);
+
+    SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
+
+    FTM_Type *ftm = (FTM_Type *)(FTM0_BASE + 0x1000 * ftm_n);
+    ftm->CONF |= FTM_CONF_BDMMODE(3);
+    ftm->SC = FTM_SC_CLKS(1) | FTM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
+    ftm->CONTROLS[ch_n].CnSC = (FTM_CnSC_MSB_MASK | FTM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
+    ftm->MODE = FTM_MODE_FTMEN_MASK;
+    ftm->SYNC = FTM_SYNC_CNTMIN_MASK;
+    ftm->SYNCONF = FTM_SYNCONF_SYNCMODE_MASK | FTM_SYNCONF_SWSOC_MASK | FTM_SYNCONF_SWWRBUF_MASK;
+    
+    //Without SYNCEN set CnV does not seem to update
+    ftm->COMBINE = FTM_COMBINE_SYNCEN0_MASK | FTM_COMBINE_SYNCEN1_MASK | FTM_COMBINE_SYNCEN2_MASK | FTM_COMBINE_SYNCEN3_MASK;
+
+    obj->CnV = &ftm->CONTROLS[ch_n].CnV;
+    obj->MOD = &ftm->MOD;
+    obj->SYNC = &ftm->SYNC;
+
+    // default to 20ms: standard for servos, and fine for e.g. brightness control
+    pwmout_period_ms(obj, 20);
+    pwmout_write(obj, 0.0);
+    
+    // Wire pinout
+    pinmap_pinout(pin, PinMap_PWM);
+}
+
+void pwmout_free(pwmout_t* obj) {}
+
+void pwmout_write(pwmout_t* obj, float value) {
+    if (value < 0.0) {
+        value = 0.0;
+    } else if (value > 1.0) {
+        value = 1.0;
+    }
+    
+    while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
+    *obj->CnV = (uint32_t)((float)(*obj->MOD + 1) * value);
+    *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;    
+}
+
+float pwmout_read(pwmout_t* obj) {
+    while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
+    float v = (float)(*obj->CnV) / (float)(*obj->MOD + 1);
+    return (v > 1.0) ? (1.0) : (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) {
+    float dc = pwmout_read(obj);
+    *obj->MOD = (uint32_t)(pwm_clock * (float)us) - 1;
+    *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
+    pwmout_write(obj, dc);
+}
+
+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) {
+    *obj->CnV = (uint32_t)(pwm_clock * (float)us);
+    *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
+}