From 013ba1f83647b5c40114c7595129f6d4cfbde215 Mon Sep 17 00:00:00 2001
From: joerg_wunsch <joerg_wunsch@81a1dc3b-b13d-400b-aceb-764788c761c2>
Date: Fri, 1 Sep 2006 21:00:36 +0000
Subject: [PATCH] Contributed by <avrdude@zevv.nl> as patch #4372: Better
 synchronization for stk500

Sync three times, and drop any noise inbetween.


git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@641 81a1dc3b-b13d-400b-aceb-764788c761c2
---
 ChangeLog |  6 ++++++
 stk500.c  | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index fb66db70..e9730e98 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2006-09-01 Joerg Wunsch <j@uriah.heep.sax.de>
+
+	Contributed by <avrdude@zevv.nl> as
+	patch #4372: Better synchronization for stk500
+	* stk500.c: Sync three times, and drop any noise inbetween.
+
 2006-09-01 Joerg Wunsch <j@uriah.heep.sax.de>
 
 	* avrdude.conf.in (ATtiny261, ATtiny461, ATtiny861): new
diff --git a/stk500.c b/stk500.c
index b131a720..170962dd 100644
--- a/stk500.c
+++ b/stk500.c
@@ -90,6 +90,16 @@ static int stk500_getsync(PROGRAMMER * pgm)
    * get in sync */
   buf[0] = Cmnd_STK_GET_SYNC;
   buf[1] = Sync_CRC_EOP;
+  
+  /*
+   * First send and drain a few times to get rid of line noise 
+   */
+   
+  stk500_send(pgm, buf, 2);
+  stk500_drain(pgm, 0);
+  stk500_send(pgm, buf, 2);
+  stk500_drain(pgm, 0);
+
   stk500_send(pgm, buf, 2);
   stk500_recv(pgm, resp, 1);
   if (resp[0] != Resp_STK_INSYNC) {