diff --git a/firmware/led.c b/firmware/led.c
index 4ea1e0d..19b52fa 100644
--- a/firmware/led.c
+++ b/firmware/led.c
@@ -1,8 +1,39 @@
 #include "config.h"
 #include "led.h"
 
+int16_t __led_pattern;
+
+/* Debug LED */
+void TISR_HANDLER(6)
+{	
+	timer_clear_txif(6);
+
+	if (__led_pattern == -1)
+		return;
+
+	__led_pattern <<= 1;
+	if (__led_pattern & 0x100) {
+		PORTBbits.RB13 = 0;  /* on */
+		__led_pattern |= 1;
+	} else {
+		PORTBbits.RB13 = 1;  /* off */
+	}
+
+	__led_pattern &= 0xff;
+}
+
 void led_init(void)
 {
 	TRISBbits.TRISB13 = 0;
 	PORTBbits.RB13 = 1;
+	__led_pattern = -1;
+
+	timer_setup_16bit(6, LED_BLINK_RATE, 1);
+	timer_set_priority(6, 1);    /* low priority */
+}
+
+/* Set a pattern (8-bit binary pattern). */
+void led_pattern(int8_t pattern)
+{
+	__led_pattern = pattern;
 }
diff --git a/firmware/led.h b/firmware/led.h
index b282df8..f64d6ef 100644
--- a/firmware/led.h
+++ b/firmware/led.h
@@ -3,16 +3,24 @@
 
 #include "config.h"
 
+#define LED_BLINK_RATE 4
+extern int16_t __led_pattern;
+
 /* Initialize LED */
 void led_init(void);
 
+/* Set a pattern (8-bit binary pattern). */
+void led_pattern(int8_t pattern);
+
 static inline void led_on(void)
 {
+	__led_pattern = -1;
 	PORTBbits.RB13 = 0;
 }
 
 static inline void led_off(void)
 {
+	__led_pattern = -1;
 	PORTBbits.RB13 = 1;
 }
 
diff --git a/firmware/mode_debug.c b/firmware/mode_debug.c
index 5c8625e..70d502e 100644
--- a/firmware/mode_debug.c
+++ b/firmware/mode_debug.c
@@ -11,21 +11,6 @@
 #include "mode.h"
 #include "zoom.h"
 
-#define DEBUG_BLINK_RATE 4
-
-/* Debug LED */
-void TISR_HANDLER(6)
-{	
-	static int toggle = 0;
-	timer_clear_txif(6);
-	
-	toggle = !toggle;
-	if (toggle)
-		led_on();
-	else
-		led_off();
-}
-
 static uint16_t dac = 32768;
 
 #define TIMER_RATE 8000
@@ -86,8 +71,10 @@ void run_debug(void)
 	char buf[4];
 	uart1_init(115200);	
 
-	timer_setup_16bit(6, DEBUG_BLINK_RATE, 1);
 	timer_setup_16bit(7, TIMER_RATE, 1);
+	timer_set_priority(7, 6);
+
+	led_pattern(0x10101010);
 
 	uart1_put_string("Zoom NILM Debug\r\n");
 
diff --git a/firmware/mode_normal.c b/firmware/mode_normal.c
index 4a4f689..87a6eaf 100644
--- a/firmware/mode_normal.c
+++ b/firmware/mode_normal.c
@@ -89,6 +89,7 @@ void send_to_pc(uint16_t adc, uint16_t dac)
 void run_normal(void)
 {
 	uart1_init(500000);
+	led_on();
 
 	/* Assume startup current is 0 */
 	dac_current = 0.0;
@@ -97,6 +98,7 @@ void run_normal(void)
 	degauss();
 
 	timer_setup_16bit(5, TIMER_RATE, 1);
+	timer_set_priority(5, 6);
 
 	while(1) {
 		if (send_data) {
diff --git a/firmware/timer.h b/firmware/timer.h
index 45ff427..9454712 100644
--- a/firmware/timer.h
+++ b/firmware/timer.h
@@ -14,17 +14,31 @@ int timer_setup_16bit(int timer, uint32_t freq, int ie);
 	__attribute__((__interrupt__,auto_psv)) _T##x##Interrupt(void)
 
 /* Clear TxIF corresponding to a timer */
-#define timer_clear_txif(timer) do { \
- if ((timer) == 1) IFS0bits.T1IF = 0; \
- if ((timer) == 2) IFS0bits.T2IF = 0; \
- if ((timer) == 3) IFS0bits.T3IF = 0; \
- if ((timer) == 4) IFS1bits.T4IF = 0; \
- if ((timer) == 5) IFS1bits.T5IF = 0; \
- if ((timer) == 6) IFS2bits.T6IF = 0; \
- if ((timer) == 7) IFS3bits.T7IF = 0; \
- if ((timer) == 8) IFS3bits.T8IF = 0; \
- if ((timer) == 9) IFS3bits.T9IF = 0; \
-} while(0)
+#define timer_clear_txif(timer) do {			\
+		if ((timer) == 1) IFS0bits.T1IF = 0;	\
+		if ((timer) == 2) IFS0bits.T2IF = 0;	\
+		if ((timer) == 3) IFS0bits.T3IF = 0;	\
+		if ((timer) == 4) IFS1bits.T4IF = 0;	\
+		if ((timer) == 5) IFS1bits.T5IF = 0;	\
+		if ((timer) == 6) IFS2bits.T6IF = 0;	\
+		if ((timer) == 7) IFS3bits.T7IF = 0;	\
+		if ((timer) == 8) IFS3bits.T8IF = 0;	\
+		if ((timer) == 9) IFS3bits.T9IF = 0;	\
+	} while(0)
+
+
+/* Set timer interrupt priority, 1-7.  Default is 4, 7 is highest */
+#define timer_set_priority(timer, pri) do { \
+		if ((timer) == 1) IPC0bits.T1IP = (pri);	\
+		if ((timer) == 2) IPC1bits.T2IP = (pri);	\
+		if ((timer) == 3) IPC2bits.T3IP = (pri);	\
+		if ((timer) == 4) IPC6bits.T4IP = (pri);	\
+		if ((timer) == 5) IPC7bits.T5IP = (pri);	\
+		if ((timer) == 6) IPC11bits.T6IP = (pri);	\
+		if ((timer) == 7) IPC12bits.T7IP = (pri);	\
+		if ((timer) == 8) IPC12bits.T8IP = (pri);	\
+		if ((timer) == 9) IPC13bits.T9IP = (pri);	\
+	} while(0)
 
 /* sleep for between "ms" and "ms+1" milliseconds */
 void msleep(int ms);