From e9aaff808ee4d55f9220c117d301eab6f4c26d05 Mon Sep 17 00:00:00 2001
From: Ben Hitchcock <ben@zensoft.com.au>
Date: Mon, 1 Dec 2014 22:43:17 +0800
Subject: [PATCH] Updates to the way that timers are forced to overflow in
 oneshot mode.

Now the current count value is saved, and then passed to the listeners.  This _should_ mean that CC3D PPM might work this time.
---
 src/main/drivers/pwm_output.c |  3 +--
 src/main/drivers/timer.c      | 26 +++++++++++++++++++++++++-
 src/main/drivers/timer.h      |  2 ++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/main/drivers/pwm_output.c b/src/main/drivers/pwm_output.c
index 098f76df3..9d4162cb3 100644
--- a/src/main/drivers/pwm_output.c
+++ b/src/main/drivers/pwm_output.c
@@ -154,8 +154,7 @@ void pwmFinishedWritingMotors(uint8_t numberMotors)
 			if(motors[index]->tim != lastTimerPtr){
 				lastTimerPtr = motors[index]->tim;
 
-				// Force an overflow by setting the UG bit
-				motors[index]->tim->EGR |= 0x0001;
+				timerForceOverflow(motors[index]->tim);
 			}
 		}
 
diff --git a/src/main/drivers/timer.c b/src/main/drivers/timer.c
index 2178db42a..b7bfda521 100644
--- a/src/main/drivers/timer.c
+++ b/src/main/drivers/timer.c
@@ -216,6 +216,7 @@ typedef struct timerConfig_s {
     timerCCHandlerRec_t *edgeCallback[CC_CHANNELS_PER_TIMER];
     timerOvrHandlerRec_t *overflowCallback[CC_CHANNELS_PER_TIMER];
     timerOvrHandlerRec_t *overflowCallbackActive; // null-terminated linkded list of active overflow callbacks
+	uint32_t forcedOverflowTimerValue;
 } timerConfig_t;
 timerConfig_t timerConfig[USED_TIMER_COUNT];
 
@@ -612,7 +613,14 @@ static void timCCxHandler(TIM_TypeDef *tim, timerConfig_t *timerConfig)
         tim_status &= mask;
         switch(bit) {
         case __builtin_clz(TIM_IT_Update):
-            capture = tim->ARR;
+
+        	if(timerConfig->forcedOverflowTimerValue != 0){
+        		capture = timerConfig->forcedOverflowTimerValue - 1;
+        		timerConfig->forcedOverflowTimerValue = 0;
+        	} else {
+        		capture = tim->ARR;
+        	}
+
             timerOvrHandlerRec_t *cb = timerConfig->overflowCallbackActive;
             while(cb) {
                 cb->fn(cb, capture);
@@ -789,3 +797,19 @@ void timerStart(void)
     }
 #endif
 }
+
+/**
+ * Force an overflow for a given timer.
+ * Saves the current value of the counter in the relevant timerConfig's forcedOverflowTimerValue variable.
+ * @param TIM_Typedef *tim The timer to overflow
+ * @return void
+ **/
+void timerForceOverflow(volatile TIM_TypeDef *tim)
+{
+	// Save the current count so that PPM reading will work on the same timer that was forced to overflow
+	uint8_t timerIndex = lookupTimerIndex((const TIM_TypeDef *)tim);
+	timerConfig[timerIndex].forcedOverflowTimerValue = tim->CNT + 1;
+
+	// Force an overflow by setting the UG bit
+	tim->EGR |= 0x0001;
+}
\ No newline at end of file
diff --git a/src/main/drivers/timer.h b/src/main/drivers/timer.h
index 08fbab597..e0cd23a14 100644
--- a/src/main/drivers/timer.h
+++ b/src/main/drivers/timer.h
@@ -117,5 +117,7 @@ void timerChInit(const timerHardware_t *timHw, channelType_t type, int irqPriori
 
 void timerInit(void);
 void timerStart(void);
+void timerForceOverflow(volatile TIM_TypeDef *tim);
 
 void configTimeBase(TIM_TypeDef *tim, uint16_t period, uint8_t mhz);  // TODO - just for migration
+