HardwareSerial: make read() block until data arrive.

This makes the HardwareSerial behavior match that of SerialUSB, and
should help avoid confusion.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/wirish/HardwareSerial.cpp b/wirish/HardwareSerial.cpp
index e78156d..3036983 100644
--- a/wirish/HardwareSerial.cpp
+++ b/wirish/HardwareSerial.cpp
@@ -118,6 +118,9 @@ void HardwareSerial::end(void) {
  */
 
 uint8 HardwareSerial::read(void) {
+    // Block until a byte becomes available, to save user confusion.
+    while (!this->available())
+        ;
     return usart_getc(this->usart_device);
 }