diff --git a/firmware/cup.c b/firmware/cup.c
index b726d52..1777f7c 100644
--- a/firmware/cup.c
+++ b/firmware/cup.c
@@ -19,7 +19,7 @@
 #define LED_RED_TEMP 800
 
 #define TARGET_TEMP_MIN 300
-#define TARGET_TEMP_MAX 1520
+#define TARGET_TEMP_MAX 1050
 
 uint8_t setting_timeout = 0;
 
@@ -109,16 +109,22 @@ ISR(PCINT0_vect)
 	{
 		dev_state = !dev_state;
 		toggle_timeout = TOGGLE_TIMEOUT;
+        if(dev_state) {
+            device_on();
+        } else {
+            device_off();
+        }
+        
 	}
 	
 	int8_t change = state_change[((input_state & 3) << 2) | (new_state & 3)];
 	if(change)
 	{
 		target += change * 6;//0.6K * 4 per step       10; // 1 celsius per step
-		//if(target < TARGET_TEMP_MIN) {target = TARGET_TEMP_MIN;}
-		//else if(target > TARGET_TEMP_MAX) {target = TARGET_TEMP_MAX;}
-		if(target < LED_GREEN_TEMP) {target = LED_GREEN_TEMP;}
-		else if(target > LED_RED_TEMP) {target = LED_RED_TEMP;}
+    	if(target < TARGET_TEMP_MIN) {target = TARGET_TEMP_MIN;}
+		else if(target > TARGET_TEMP_MAX) {target = TARGET_TEMP_MAX;}
+		//if(target < LED_GREEN_TEMP) {target = LED_GREEN_TEMP;}
+		//else if(target > LED_RED_TEMP) {target = LED_RED_TEMP;}
 		setting_timeout = TIMEOUT;
 	}
 	
@@ -210,10 +216,6 @@ inline void led_init(void)
 
 inline void led_set(uint16_t value)
 {
-    if(!led_is_on){
-        led_init();
-        led_is_on = 1;
-    }
     uint8_t pwmval;
 	if (LED_GREEN_TEMP <= value && value < LED_RED_TEMP) {
 		pwmval = ((uint32_t) (value-LED_GREEN_TEMP) * 255)/(LED_RED_TEMP-LED_GREEN_TEMP);
@@ -228,13 +230,28 @@ inline void led_set(uint16_t value)
 
 inline void led_off(void)
 {
-    led_is_on = 0;
-    TCCR0B = 0; // stop pwm
-    TCCR0A = 0; // disconnect outputs;
 //	OCR0A = 0;
 //	OCR0B = 255;
 }
 
+inline void device_off(void)
+{
+    TCCR0B = 0; // stop pwm
+    TCCR0A = 0; // disconnect outputs;
+    ADCSRA &= ~(1<<ADEN); // disable adc
+    heat_power = 0; // turn off heating
+}
+
+inline void device_on(void)
+{
+    led_init();
+    ADCSRA |= (1<<ADEN); // enable adc
+    ADCSRA |= (1<<ADSC); // start a conversion to be sure
+}
+
+
+
+
 inline void adc_init(void)
 {
 	ADMUX = (1 << REFS1) | (TEMP_PIN << MUX0);/* Vref = 1.1, pin selection */
@@ -275,6 +292,8 @@ int main(void)
 	led_init();
 	sei();
 	
+    device_off(); // initial state
+
 	for(;;)
 	{
 		if(ADCSRA & (1 << ADIF))
@@ -303,7 +322,8 @@ int main(void)
 			}
 		}
 		
-		if(!dev_state) {led_off();}
+		//if(!dev_state) {led_off();}
+                // now done in interrupt
 		else if(setting_timeout) {led_set(target);}
 		else {led_set(temperature);}
 		
@@ -326,6 +346,7 @@ int main(void)
         if(!dev_state) {
             set_sleep_mode(SLEEP_MODE_IDLE);
             sleep_mode();
+            // timer1 interrupt will wake us again, as will PCINT
         }    
 	}