Fix 'wait_for_pulse' when timer is not running

Checks if timer is running to allow waiting for the pulse to complete. Also moves the pulse wait function before the 'configure' step b/c configure stops the timer and therefore the pulse would never be waited for.

Author: oclyke

cores/arduino/ard_sup/analog/ap3_analog.cpp

@@ -354,34 +354,73 @@ ap3_err_t ap3_change_channel(uint8_t padNumber)
 }
 
 
+bool ap3_pwm_is_running(uint32_t ui32TimerNumber, uint32_t ui32TimerSegment){
+    volatile uint32_t *pui32ConfigReg;
+    bool is_enabled = false;
+
+    //
+    // Find the correct control register.
+    //
+    pui32ConfigReg = (uint32_t*)CTIMERADDRn(CTIMER, ui32TimerNumber, CTRL0);
+
+    //
+    // Begin critical section while config registers are read and modified.
+    //
+    AM_CRITICAL_BEGIN
+
+    //
+    // Read the current value.
+    //
+    uint32_t ui32ConfigVal = *pui32ConfigReg;
+
+    //
+    // Check the "enable bit"
+    //
+    if( ui32ConfigVal & (CTIMER_CTRL0_TMRA0EN_Msk | CTIMER_CTRL0_TMRB0EN_Msk) ){
+        is_enabled = true;
+    }
+
+    //
+    // Done with critical section.
+    //
+    AM_CRITICAL_END
+
+    return is_enabled;
+}
+
+
 void ap3_pwm_wait_for_pulse(uint32_t timer, uint32_t segment, uint32_t output, uint32_t margin){
 
     volatile uint32_t *pui32CompareReg;
     volatile uint32_t ctimer_val;
     uint32_t cmpr0;
 
-    // Get the comapre register address
-    if( segment == AM_HAL_CTIMER_TIMERA ){
-        if( output == AM_HAL_CTIMER_OUTPUT_NORMAL ){
-            pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRA0);
-        }else{
-            pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRAUXA0);
-        }
-    }else{
-        if( output == AM_HAL_CTIMER_OUTPUT_NORMAL ){
-            pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRB0);
+    // Only wait if the ctimer is running to avoid a deadlock
+    if( ap3_pwm_is_running( timer, segment) ){
+
+        // Get the comapre register address
+        if( segment == AM_HAL_CTIMER_TIMERA ){
+            if( output == AM_HAL_CTIMER_OUTPUT_NORMAL ){
+                pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRA0);
+            }else{
+                pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRAUXA0);
+            }
         }else{
-            pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRAUXB0);
+            if( output == AM_HAL_CTIMER_OUTPUT_NORMAL ){
+                pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRB0);
+            }else{
+                pui32CompareReg = (uint32_t*)CTIMERADDRn(CTIMER, timer, CMPRAUXB0);
+            }
         }
-    }
 
-    // Get the compare value
-    cmpr0 = ((uint32_t)(*(pui32CompareReg)) & 0x0000FFFF);
-    
-    // Wait for the timer value to be less than the compare value so that it is safe to change
-    ctimer_val = am_hal_ctimer_read( timer, segment);
-    while( (ctimer_val + 0) > cmpr0 ){
+        // Get the compare value
+        cmpr0 = ((uint32_t)(*(pui32CompareReg)) & 0x0000FFFF);
+        
+        // Wait for the timer value to be less than the compare value so that it is safe to change
         ctimer_val = am_hal_ctimer_read( timer, segment);
+        while( (ctimer_val + 0) > cmpr0 ){
+            ctimer_val = am_hal_ctimer_read( timer, segment);
+        }
     }
 }
 
@@ -494,6 +533,9 @@ ap3_err_t ap3_pwm_output(uint8_t pin, uint32_t th, uint32_t fw, uint32_t clk)
         output = AM_HAL_CTIMER_OUTPUT_FORCE1;
     }
 
+    // Wait until after high pulse to change the state (avoids inversion)
+    ap3_pwm_wait_for_pulse( timer, segment, output, 10);
+
     // Configure the pin
     am_hal_ctimer_output_config(timer,
                                 segment,
@@ -507,9 +549,6 @@ ap3_err_t ap3_pwm_output(uint8_t pin, uint32_t th, uint32_t fw, uint32_t clk)
                                 // (AM_HAL_CTIMER_FN_PWM_REPEAT | AP3_ANALOG_CLK | AM_HAL_CTIMER_INT_ENABLE) );
                                 (AM_HAL_CTIMER_FN_PWM_REPEAT | clk));
 
-    // Wait until after high pulse to change the state (avoids inversion)
-    ap3_pwm_wait_for_pulse( timer, segment, output, 10);
-
     // If this pad uses secondary output:
     if (output == AM_HAL_CTIMER_OUTPUT_SECONDARY)
     {