diff --git a/firmware/main.c b/firmware/main.c
index 22c7cea..b60f45f 100755
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -363,6 +363,21 @@ int main(void) {
 
 	/* main event loop */
 	usbInit();
+
+#ifdef TEST_TARGET_AS_SPI_MASTER
+	DDRB = (1 << PB2 | 1 << PB3 | 1 << PB5);
+	PORTB &= (1 << PB2);
+	SPCR = (1 << SPE | 1 << MSTR | 1 << SPR1 | 1 << SPR0);
+	sei();
+	for (;;) {
+		if (--blink_counter == 0) {
+			toggleLedRed();
+			blink_counter = (unsigned int)(1UL << 19);
+			SPDR = i++;
+		}
+	}
+#endif
+
 	sei();
 	for (;;) {
 		usbPoll();