From caa51253db04cb6090ec3e5dc2cd318e9f433d8e Mon Sep 17 00:00:00 2001
From: Alessio Morale <alessiomorale@gmail.com>
Date: Mon, 19 Jan 2015 21:55:40 +0100
Subject: [PATCH] OP-1682 - Workaround overflow issue with pwm receiver inputs
 on shared timers.

---
 flight/pios/inc/pios_pwm.h       |  2 ++
 flight/pios/stm32f10x/pios_pwm.c | 19 ++++++++++++-------
 flight/pios/stm32f10x/pios_tim.c | 24 +++++++++++-------------
 3 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/flight/pios/inc/pios_pwm.h b/flight/pios/inc/pios_pwm.h
index 3552319c9..da3de8409 100644
--- a/flight/pios/inc/pios_pwm.h
+++ b/flight/pios/inc/pios_pwm.h
@@ -30,4 +30,6 @@
 #ifndef PIOS_PWM_H
 #define PIOS_PWM_H
 
+#define PIOS_PWM_VALID_RANGE_MAX 2250
+#define PIOS_PWM_VALID_RANGE_MIN 750
 #endif /* PIOS_PWM_H */
diff --git a/flight/pios/stm32f10x/pios_pwm.c b/flight/pios/stm32f10x/pios_pwm.c
index a583414bd..f29204fed 100644
--- a/flight/pios/stm32f10x/pios_pwm.c
+++ b/flight/pios/stm32f10x/pios_pwm.c
@@ -209,8 +209,10 @@ static void PIOS_PWM_tim_overflow_cb(__attribute__((unused)) uint32_t tim_id, ui
         /* Channel out of range */
         return;
     }
-
-    pwm_dev->us_since_update[channel] += count;
+    if (!pwm_dev->CaptureState[channel]) {
+        return;
+    }
+    pwm_dev->us_since_update[channel] = +count;
     if (pwm_dev->us_since_update[channel] >= PWM_SUPERVISOR_TIMEOUT) {
         pwm_dev->CaptureState[channel]    = 0;
         pwm_dev->RiseValue[channel]       = 0;
@@ -256,16 +258,19 @@ static void PIOS_PWM_tim_edge_cb(__attribute__((unused)) uint32_t tim_id, uint32
         TIM_ICInitStructure.TIM_Channel    = chan->timer_chan;
         TIM_ICInit(chan->timer, &TIM_ICInitStructure);
     } else {
+        uint32_t value = 0;
         /* Capture computation */
         if (pwm_dev->FallValue[chan_idx] > pwm_dev->RiseValue[chan_idx]) {
-            pwm_dev->CaptureValue[chan_idx] = (pwm_dev->FallValue[chan_idx] - pwm_dev->RiseValue[chan_idx]);
+            value = pwm_dev->us_since_update[chan_idx] + (pwm_dev->FallValue[chan_idx] - pwm_dev->RiseValue[chan_idx]);
         } else {
-            pwm_dev->CaptureValue[chan_idx] = ((chan->timer->ARR - pwm_dev->RiseValue[chan_idx]) + pwm_dev->FallValue[chan_idx]);
+            value = pwm_dev->us_since_update[chan_idx] + (pwm_dev->FallValue[chan_idx] - pwm_dev->RiseValue[chan_idx]);
+        }
+        if (PIOS_PWM_VALID_RANGE_MAX > value && PIOS_PWM_VALID_RANGE_MIN < value) {
+            pwm_dev->CaptureValue[chan_idx] = value;
         }
-
         /* Switch states */
-        pwm_dev->CaptureState[chan_idx] = 0;
-
+        pwm_dev->CaptureState[chan_idx]    = 0;
+        pwm_dev->us_since_update[chan_idx] = 0;
         /* Increase supervisor counter */
         pwm_dev->CapCounter[chan_idx]++;
 
diff --git a/flight/pios/stm32f10x/pios_tim.c b/flight/pios/stm32f10x/pios_tim.c
index d585c3fd7..ca9bd6254 100644
--- a/flight/pios/stm32f10x/pios_tim.c
+++ b/flight/pios/stm32f10x/pios_tim.c
@@ -159,6 +159,16 @@ out_fail:
 
 static void PIOS_TIM_generic_irq_handler(TIM_TypeDef *timer)
 {
+    /* Check for an overflow event on this timer */
+    bool overflow_event     = 0;
+    uint16_t overflow_count = false;
+
+    if (TIM_GetITStatus(timer, TIM_IT_Update) == SET) {
+        TIM_ClearITPendingBit(timer, TIM_IT_Update);
+        overflow_count = timer->ARR;
+        overflow_event = true;
+    }
+
     /* Iterate over all registered clients of the TIM layer to find channels on this timer */
     for (uint8_t i = 0; i < pios_tim_num_devs; i++) {
         const struct pios_tim_dev *tim_dev = &pios_tim_devs[i];
@@ -168,18 +178,6 @@ static void PIOS_TIM_generic_irq_handler(TIM_TypeDef *timer)
             continue;
         }
 
-        /* Check for an overflow event on this timer */
-        bool overflow_event;
-        uint16_t overflow_count;
-        if (TIM_GetITStatus(timer, TIM_IT_Update) == SET) {
-            TIM_ClearITPendingBit(timer, TIM_IT_Update);
-            overflow_count = timer->ARR;
-            overflow_event = true;
-        } else {
-            overflow_count = 0;
-            overflow_event = false;
-        }
-
         for (uint8_t j = 0; j < tim_dev->num_channels; j++) {
             const struct pios_tim_channel *chan = &tim_dev->channels[j];
 
@@ -255,7 +253,7 @@ static void PIOS_TIM_generic_irq_handler(TIM_TypeDef *timer)
                  *            edge happened just after the overflow.
                  */
 
-                if (edge_count < 16) {
+                if (edge_count < 32) {
                     /* Call the overflow callback first */
                     if (tim_dev->callbacks->overflow) {
                         (*tim_dev->callbacks->overflow)((uint32_t)tim_dev,