From 2218a05652ac9890cbef742f5c6d306a8b4b8902 Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Thu, 7 Sep 2017 17:21:28 +0200
Subject: [PATCH] Avoid stalling if uart buffer becomes full

---
 cores/arduino/Uart.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/cores/arduino/Uart.cpp b/cores/arduino/Uart.cpp
index adc73146f..16afe4e41 100644
--- a/cores/arduino/Uart.cpp
+++ b/cores/arduino/Uart.cpp
@@ -110,7 +110,11 @@ size_t Uart::write(const uint8_t data)
   if (sercom->isDataRegisterEmptyUART() && txBuffer.available() == 0) {
     sercom->writeDataUART(data);
   } else {
-    while(txBuffer.isFull()); // spin lock until a spot opens up in the buffer
+    while (txBuffer.isFull()) {
+      // Pretend an interrupt has happened and
+      // call the handler to free up space for us.
+      IrqHandler();
+    };
 
     txBuffer.store_char(data);