From 69a74b2095fcf50b41083e19e197a3d62e3dc81c Mon Sep 17 00:00:00 2001
From: Michael Vogt <michu@neophob.com>
Date: Sat, 13 Apr 2013 23:12:07 +0200
Subject: [PATCH] fix bug #1354: I2C/TWI Library: Buffer Overflow

---
 libraries/Wire/src/utility/twi.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/libraries/Wire/src/utility/twi.c b/libraries/Wire/src/utility/twi.c
index 171af73..a2fa2c5 100644
--- a/libraries/Wire/src/utility/twi.c
+++ b/libraries/Wire/src/utility/twi.c
@@ -509,8 +509,14 @@ ISR(TWI_vect)
       break;
     case TW_SR_DATA_NACK:       // data received, returned nack
     case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
-      // nack back at master
-      twi_reply(0);
+      // We replied a nack, this happens when the buffer overflows.
+      // After this interrupt we don't get a TW_SR_STOP interrupt, so
+      // clean up now
+
+      // Discard the data, it is incomplete
+      twi_rxBufferIndex = 0;
+      // ack future responses and leave slave receiver state
+      twi_releaseBus();    
       break;
     
     // Slave Transmitter