Diff: targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c

Revision:

0:9b334a45a8ff

Child:

50:a417edff4437

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pwmout_api.c	Thu Oct 01 15:25:22 2015 +0300
@@ -0,0 +1,221 @@
+/***************************************************************************//**
+ * @file pwmout_api.c
+ *******************************************************************************
+ * @section License
+ * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
+ *******************************************************************************
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ *
+ * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
+ * obligation to support this Software. Silicon Labs is providing the
+ * Software "AS IS", with no express or implied warranties of any kind,
+ * including, but not limited to, any implied warranties of merchantability
+ * or fitness for any particular purpose or warranties against infringement
+ * of any proprietary rights of a third party.
+ *
+ * Silicon Labs will not be liable for any consequential, incidental, or
+ * special damages, or any other relief, or for any claim by any third party,
+ * arising from your use of this Software.
+ *
+ ******************************************************************************/
+
+#include "device.h"
+#include "clocking.h"
+#if DEVICE_PWMOUT
+
+#include "mbed_assert.h"
+#include "pwmout_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+#include "PeripheralPins.h"
+#include "device_peripherals.h"
+#include "sleepmodes.h"
+
+#include "em_cmu.h"
+#include "em_gpio.h"
+#include "em_timer.h"
+
+static int pwm_prescaler_div;
+
+uint32_t pwmout_get_channel_route(pwmout_t *obj)
+{
+    MBED_ASSERT(obj->channel != (PWMName) NC);
+
+    switch (obj->channel) {
+        case PWM_CH0:
+            return TIMER_ROUTE_CC0PEN;
+            break;
+        case PWM_CH1:
+            return TIMER_ROUTE_CC1PEN;
+            break;
+        case PWM_CH2:
+            return TIMER_ROUTE_CC2PEN;
+            break;
+        default:
+            return 0;
+    }
+}
+
+void pwmout_enable_pins(pwmout_t *obj, uint8_t enable)
+{
+    if (enable) {
+        pin_mode(obj->pin, PushPull);
+    } else {
+        // TODO_LP return PinMode to the previous state
+        pin_mode(obj->pin, Disabled);
+    }
+}
+
+void pwmout_enable(pwmout_t *obj, uint8_t enable)
+{
+    /* Start with default CC (Compare/Capture) channel parameters */
+    TIMER_InitCC_TypeDef timerCCInit = TIMER_INITCC_DEFAULT;
+    if (enable) {
+        /* Set mode to PWM */
+        timerCCInit.mode = timerCCModePWM;
+    }
+
+    /* Configure CC channel */
+    TIMER_InitCC(PWM_TIMER, obj->channel, &timerCCInit);
+}
+
+void pwmout_init(pwmout_t *obj, PinName pin)
+{
+    obj->channel = (PWMName) pinmap_peripheral(pin, PinMap_PWM);
+    obj->pin = pin;
+    MBED_ASSERT(obj->channel != (PWMName) NC);
+
+    /* Turn on clock */
+    CMU_ClockEnable(PWM_TIMER_CLOCK, true);
+
+    /* Turn on timer */
+    if(!(PWM_TIMER->STATUS & TIMER_STATUS_RUNNING)) {
+        TIMER_Init_TypeDef timerInit = TIMER_INIT_DEFAULT;
+        TIMER_Init(PWM_TIMER, &timerInit);
+    }
+
+    /* Enable correct channel */
+    uint32_t routeloc = pwmout_get_channel_route(obj);
+    if(PWM_TIMER->ROUTE & routeloc) {
+        //This channel was already in use
+        //TODO: gracefully handle this case
+    } else {
+        //This channel was unused up to now
+        PWM_TIMER->ROUTE |= routeloc;
+        blockSleepMode(EM1);
+
+        //TODO: check if any channel was up already, then don't re-init timer
+        pwmout_enable(obj, true);
+        pwmout_enable_pins(obj, true);
+    }
+
+    /* Route correct channel to location 1 */
+    PWM_TIMER->ROUTE &= ~_TIMER_ROUTE_LOCATION_MASK;
+    PWM_TIMER->ROUTE |= PWM_ROUTE;
+
+    /* Set default 20ms frequency and 0ms pulse width */
+    pwmout_period(obj, 0.02);
+}
+
+void pwmout_free(pwmout_t *obj)
+{
+    uint32_t routeloc = pwmout_get_channel_route(obj);
+    if(PWM_TIMER->ROUTE & routeloc) {
+        //This channel was in use, so disable
+        PWM_TIMER->ROUTE &= ~routeloc;
+        pwmout_enable_pins(obj, false);
+        unblockSleepMode(EM1);
+
+        //TODO: check if all channels are down, then switch off timer
+    } else {
+        //This channel was disabled already
+    }
+}
+
+void pwmout_write(pwmout_t *obj, float value)
+{
+    if (value < 0.0f) {
+        value = 0;
+    } else if (value > 1.0f) {
+        value = 1;
+    }
+
+    float pulse_period_in_s = obj->period_cycles / ((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div));
+    pwmout_pulsewidth(obj, value * pulse_period_in_s);
+}
+
+float pwmout_read(pwmout_t *obj)
+{
+    return obj->width_cycles / (float) obj->period_cycles;
+}
+
+// Set the PWM period, keeping the absolute pulse width the same.
+void pwmout_period(pwmout_t *obj, float seconds)
+{
+    // Find the lowest prescaler divider possible.
+    // This gives us max resolution for a given period
+
+    //The value of the top register if prescaler is set to 0
+    int cycles = REFERENCE_FREQUENCY * seconds;
+    pwm_prescaler_div = 0;
+
+    //The top register is only 16 bits, so we keep dividing till we are below 0xFFFF
+    while (cycles > 0xFFFF) {
+        cycles /= 2;
+        pwm_prescaler_div++;
+
+        //Max pwm_prescaler_div supported is 10
+        if (pwm_prescaler_div > 10) {
+            pwm_prescaler_div = 10;
+            cycles = 0xFFFF; //Set it to max possible value;
+            break;
+        }
+    }
+
+    obj->period_cycles = cycles;
+
+    //Set prescaler
+    PWM_TIMER->CTRL = (PWM_TIMER->CTRL & ~_TIMER_CTRL_PRESC_MASK) | (pwm_prescaler_div << _TIMER_CTRL_PRESC_SHIFT);
+
+    /* Set Top Value, which controls the PWM period */
+    TIMER_TopSet(PWM_TIMER, obj->period_cycles);
+}
+
+void pwmout_period_ms(pwmout_t *obj, int ms)
+{
+    pwmout_period(obj, ms / 1000.0f);
+}
+
+void pwmout_period_us(pwmout_t *obj, int us)
+{
+    pwmout_period(obj, us / 1000000.0f);
+}
+
+void pwmout_pulsewidth(pwmout_t *obj, float seconds)
+{
+    obj->width_cycles = (uint32_t) (((float) (REFERENCE_FREQUENCY >> pwm_prescaler_div)) * seconds);
+    TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
+}
+
+void pwmout_pulsewidth_ms(pwmout_t *obj, int ms)
+{
+    obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * ms) / 1000;
+    TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
+}
+
+void pwmout_pulsewidth_us(pwmout_t *obj, int us)
+{
+    obj->width_cycles = (uint32_t) ((REFERENCE_FREQUENCY >> pwm_prescaler_div) * us) / 1000000;
+    TIMER_CompareBufSet(PWM_TIMER, obj->channel, obj->width_cycles);
+}
+
+#endif