From c4506ed869ff255993c8cae3ca847689c8c42236 Mon Sep 17 00:00:00 2001
From: Paul Sokolovsky <pfalcon@users.sourceforge.net>
Date: Tue, 29 Mar 2016 21:10:10 +0300
Subject: [PATCH] esp8266: Let esp8266 "os" messages go to standard (REPL)
 UART.

That's definitely helpful for debugging.
---
 esp8266/Makefile | 4 +++-
 esp8266/uart.c   | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/esp8266/Makefile b/esp8266/Makefile
index 50862623d5..306935210e 100644
--- a/esp8266/Makefile
+++ b/esp8266/Makefile
@@ -23,7 +23,9 @@ INC += -I../lib/timeutils
 INC += -I$(BUILD)
 INC += -I$(ESP_SDK)/include
 
-UART_OS = 1
+# UART for "os" messages. 0 is normal UART as used by MicroPython REPL,
+# 1 is debug UART (tx only).
+UART_OS = 0
 
 CFLAGS_XTENSA = -fsingle-precision-constant -Wdouble-promotion \
 	-D__ets__ -DICACHE_FLASH \
diff --git a/esp8266/uart.c b/esp8266/uart.c
index 942c397e90..4f45a952ba 100644
--- a/esp8266/uart.c
+++ b/esp8266/uart.c
@@ -205,7 +205,7 @@ void ICACHE_FLASH_ATTR uart_init(UartBautRate uart0_br, UartBautRate uart1_br) {
     uart_config(UART1);
     ETS_UART_INTR_ENABLE();
 
-    // install uart1 putc callback
+    // install handler for "os" messages
     os_install_putc1((void *)uart_os_write_char);
 }