Fix up serial debug output

diff --git a/src/ao_serial.c b/src/ao_serial.c
index f2f5e69736e6540f07572d90b9ba45a163337059..7bc11b979ac38137abd5e62c4a263711c5f097bf 100644 (file)
--- a/src/ao_serial.c
+++ b/src/ao_serial.c
@@ -60,7 +60,7 @@ ao_serial_getchar(void) __critical
                ao_sleep(&ao_usart1_rx_fifo);
        ao_fifo_remove(ao_usart1_rx_fifo, c);
        if (serial_echo) {
-               printf("%02x\n", (uint8_t) c);
+               printf("%02x\n", ((int) c) & 0xff);
                flush();
        }
        return c;