From ef9139a98cc45ccbfacb779d03b10d84d1fa4b44 Mon Sep 17 00:00:00 2001
From: Nathael Pajani <nathael.pajani@ed3l.fr>
Date: Wed, 24 May 2017 14:44:21 +0200
Subject: [PATCH] Add flushes and instruction barriers so that GCC does what we
 need with the Tx line on the communication port.

---
 v04/main.c | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/v04/main.c b/v04/main.c
index be8d52f..ef4dae6 100644
--- a/v04/main.c
+++ b/v04/main.c
@@ -29,6 +29,7 @@
 #include "core/pio.h"
 #include "core/iap.h"
 #include "lib/stdio.h"
+#include "lib/utils.h"
 #include "drivers/i2c.h"
 #include "drivers/adc.h"
 #include "drivers/serial.h"
@@ -47,20 +48,30 @@
 #define SELECTED_FREQ  FREQ_SEL_36MHz
 
 
-#define DEBUG 0
-#if (DEBUG == 1)
+#define DEBUG 1
+#if (DEBUG == 1) /* Send only on prog output */
+ #define debug_printf(...) \
+	uprintf(__VA_ARGS__); \
+
+ #define debug(cond, ...) \
+    if (cond) { \
+		uprintf(UART0, __VA_ARGS__ ); \
+	}
+
+#elif (DEBUG == 2) /* Send on comm port */
  #define debug_printf(...) \
 	gpio_clear(tx_en); \
 	uprintf(__VA_ARGS__); \
+	serial_flush(UART0); \
 	gpio_set(tx_en);
 
  #define debug(cond, ...) \
     if (cond) { \
 		gpio_clear(tx_en); \
 		uprintf(UART0, __VA_ARGS__ ); \
+		serial_flush(UART0); \
 		gpio_set(tx_en); \
 	}
-
 #else
  #define debug_printf(...) ;
  #define debug(...) ;
@@ -435,11 +446,18 @@ int main(void)
 		/* Get hold of Tx line */
 		if (need_config == 1) {
 			/* Request a new address from host */
+			serial_flush(UART0);
+			/* Do not place any of the following instructions before the flush end */
+			isb();
 			gpio_clear(tx_en);
-			if (serial_send_quickbyte(UART0, 'c') == 0) {
+			if (serial_write(UART0, "$c", 2) == 2) {
 				addr_req = 1;
 				need_config = 0;
 			}
+			/* And wait for fush end before relaesing the line */
+			isb();
+			serial_flush(UART0);
+			isb();
 			gpio_set(tx_en);
 		}
 
@@ -481,7 +499,7 @@ int main(void)
 			if (1) {
 				char buff[20];
 				uint16_t* data = (uint16_t*)buff;
-
+				memset(buff, 0, 20);
 				buff[0] = '#';
 				buff[1] = address | (got_tsl << 5) | (got_veml << 6) | (got_bme << 7);
 				data[1] = (uint16_t)htons(raw_humidity);
@@ -492,8 +510,15 @@ int main(void)
 				data[6] = (uint16_t)htons(comp_temp);
 				data[7] = (uint16_t)htons(humidity);
 
+				serial_flush(UART0);
+				/* Do not place any of the following instructions before the flush end */
+				isb();
 				gpio_clear(tx_en);
 				serial_write(UART0, buff, 20);
+				/* And wait for fush end before relaesing the line */
+				isb();
+				serial_flush(UART0);
+				isb();
 				gpio_set(tx_en);
 			}
 		}
-- 
2.43.0