From a454f06bf82ce4d036e4f9d1379a39247631bd61 Mon Sep 17 00:00:00 2001
From: peabody124 <peabody124>
Date: Tue, 23 Nov 2010 17:13:48 +0000
Subject: [PATCH] OP-203 PIOS_UART: Tweaked the way the interrupts are
 reenabled to get comms stable again

git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@2143 ebee16cc-31ac-478f-84a7-5cbb03baadba
---
 flight/PiOS/STM32F10x/pios_usart.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/flight/PiOS/STM32F10x/pios_usart.c b/flight/PiOS/STM32F10x/pios_usart.c
index 00c8dd7f8..7745f2ad4 100644
--- a/flight/PiOS/STM32F10x/pios_usart.c
+++ b/flight/PiOS/STM32F10x/pios_usart.c
@@ -202,7 +202,7 @@ int32_t PIOS_USART_RxBufferGet(uint8_t usart)
 		return -2;
 	}
 
-	if (!fifoBuf_getUsed(&usart_dev->rx)) {
+	if (fifoBuf_getUsed(&usart_dev->rx) == 0) {
 		/* Nothing new in the buffer */
 		return -1;
 	}
@@ -395,12 +395,11 @@ int32_t PIOS_USART_TxBufferPutMoreNonBlocking(uint8_t usart, const uint8_t * buf
 	/* Copy bytes to be transmitted into transmit buffer */
 	/* This operation should be atomic! */
 	PIOS_IRQ_Disable();
+	uint16_t used = fifoBuf_getUsed(&usart_dev->tx);
 	fifoBuf_putData(&usart_dev->tx,buffer,len);
-
-	if (fifoBuf_getUsed(&usart_dev->tx) == len) {
-		/* Buffer has just become non-empty, enable tx interrupt. */
+	
+	if(used == 0) /* enable sending when was empty */
 		USART_ITConfig(usart_dev->cfg->regs, USART_IT_TXE, ENABLE);
-	}
 	PIOS_IRQ_Enable();
 
 	/* No error */