From c9c4691b55ad12bf434bf3f03e3f562037dddf92 Mon Sep 17 00:00:00 2001
From: Arnaud Taffanel <arnaud@bitcraze.io>
Date: Mon, 3 Sep 2018 15:48:49 +0200
Subject: [PATCH] Closes #367: Handle overrun condition in deck Uart1 driver

---
 src/drivers/interface/uart1.h |  8 ++++++++
 src/drivers/src/uart1.c       | 21 +++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/drivers/interface/uart1.h b/src/drivers/interface/uart1.h
index 817c120e28..f23ac6ed82 100644
--- a/src/drivers/interface/uart1.h
+++ b/src/drivers/interface/uart1.h
@@ -89,6 +89,14 @@ int uart1Putchar(int ch);
 
 void uart1Getchar(char * ch);
 
+/**
+ * Returns true if an overrun condition has happened since initialisation or
+ * since the last call to this funcion.
+ * 
+ * @return true if an overrun condition has happened
+ */
+bool uart1DidOverrun();
+
 /**
  * Uart printf macro that uses eprintf
  * @param[in] FMT String format
diff --git a/src/drivers/src/uart1.c b/src/drivers/src/uart1.c
index 206540c9f1..0a7ff99694 100644
--- a/src/drivers/src/uart1.c
+++ b/src/drivers/src/uart1.c
@@ -25,6 +25,8 @@
  */
 #include <string.h>
 
+#include "stm32fxxx.h"
+
 /*FreeRtos includes*/
 #include "FreeRTOS.h"
 #include "queue.h"
@@ -42,6 +44,7 @@
 
 static xQueueHandle uart1queue;
 static bool isInit = false;
+static bool hasOverrun = false;
 
 void uart1Init(const uint32_t baudrate)
 {
@@ -139,6 +142,14 @@ void uart1Getchar(char * ch)
   xQueueReceive(uart1queue, ch, portMAX_DELAY);
 }
 
+bool uart1DidOverrun()
+{
+  bool result = hasOverrun;
+  hasOverrun = false;
+
+  return result;
+}
+
 void __attribute__((used)) USART3_IRQHandler(void)
 {
   uint8_t rxData;
@@ -148,5 +159,15 @@ void __attribute__((used)) USART3_IRQHandler(void)
   {
     rxData = USART_ReceiveData(UART1_TYPE) & 0x00FF;
     xQueueSendFromISR(uart1queue, &rxData, &xHigherPriorityTaskWoken);
+  } else {
+    /** if we get here, the error is most likely caused by an overrun!
+     * - PE (Parity error), FE (Framing error), NE (Noise error), ORE (OverRun error)
+     * - and IDLE (Idle line detected) pending bits are cleared by software sequence:
+     * - reading USART_SR register followed reading the USART_DR register.
+     */
+    asm volatile ("" : "=m" (UART1_TYPE->SR) : "r" (UART1_TYPE->SR)); // force non-optimizable reads
+    asm volatile ("" : "=m" (UART1_TYPE->DR) : "r" (UART1_TYPE->DR)); // of these two registers
+
+    hasOverrun = true;
   }
 }