diff --git a/firmware/cup.c b/firmware/cup.c
index a7ce9a5..c2f0cc5 100644
--- a/firmware/cup.c
+++ b/firmware/cup.c
@@ -10,7 +10,7 @@
 #define FET0_PIN 0
 #define FET1_PIN 1
 
-#define TIMEOUT 255
+#define TIMEOUT 51 /* 2 seconds */
 
 uint8_t led_color = 0;
 
@@ -72,7 +72,7 @@ ISR(PCINT0_vect)
 //                    uC ADC pin (with 1.11V reference)
 uint16_t linearize_temp(uint16_t temp_in)
 {
-	static const uint16_t one_point_one_volt = 65472; //2^16-2^6
+	static const uint16_t one_point_one_volt = (1 << 16) - (1 << 6);/* max value from 64 adc mesaurements */
 	uint16_t temp_out = ~0; //burning
 	// made from datasheet by:
 	// for i in 677 740 807 877 951 1029 1111 1196 1286 1378 1475 1575 1679 1786 1896 2003 2103 2189; do calc 5*$i/9860*65472/1.11; done
@@ -149,8 +149,9 @@ void adc_init(void)
 
 void heat_init(void)
 {
-	TCCR1B = (1 << CS12) | (1 << CS10);/* prescaler / 1024 */
+	TCCR1B = (1 << WGM12) | (1 << CS10);/* some mode allowing to set timer TOP, no prescaler */
 	TIMSK1 = (1 << TOIE1);/* interupt on overflow */
+	OCR1A = 39063;
 	/* insert loading of heat setting here */
 }