Diff: targets/hal/TARGET_STM/TARGET_STM32F3/pwmout_api.c

Revision:

123:5dbefb20d136

Parent:

0:9b334a45a8ff

Child:

144:ef7eb2e8f9f7

--- a/targets/hal/TARGET_STM/TARGET_STM32F3/pwmout_api.c	Wed May 04 22:30:12 2016 +0100
+++ b/targets/hal/TARGET_STM/TARGET_STM32F3/pwmout_api.c	Thu May 05 21:00:11 2016 +0100
@@ -96,7 +96,7 @@
 
     // Configure channels
     sConfig.OCMode       = TIM_OCMODE_PWM1;
-    sConfig.Pulse        = obj->pulse;
+    sConfig.Pulse        = obj->pulse / obj->prescaler;
     sConfig.OCPolarity   = TIM_OCPOLARITY_HIGH;
     sConfig.OCNPolarity  = TIM_OCNPOLARITY_HIGH;
     sConfig.OCFastMode   = TIM_OCFAST_DISABLE;
@@ -161,8 +161,26 @@
     // Update the SystemCoreClock variable
     SystemCoreClockUpdate();
 
-    TimHandle.Init.Period        = us - 1;
-    TimHandle.Init.Prescaler     = (uint16_t)(SystemCoreClock / 1000000) - 1; // 1 us tick
+    /* To make it simple, we use to possible prescaler values which lead to:
+     * pwm unit = 1us, period/pulse can be from 1us to 65535us
+     * or
+     * pwm unit = 500us, period/pulse can be from 500us to ~32.76sec
+     * Be careful that all the channels of a PWM shares the same prescaler
+     */
+    if (us >  0xFFFF) {
+        obj->prescaler = 500;
+    } else {
+        obj->prescaler = 1;
+    }
+    TimHandle.Init.Prescaler     = ((SystemCoreClock / 1000000) * obj->prescaler) - 1;
+
+    if (TimHandle.Init.Prescaler > 0xFFFF)
+        error("PWM: out of range prescaler");
+
+    TimHandle.Init.Period        = (us - 1) / obj->prescaler;
+    if (TimHandle.Init.Period > 0xFFFF)
+        error("PWM: out of range period");
+
     TimHandle.Init.ClockDivision = 0;
     TimHandle.Init.CounterMode   = TIM_COUNTERMODE_UP;