diff --git a/Timelapse_keyboard/GPS.c b/Timelapse_keyboard/GPS.c
index 639a79d..b684f42 100644
--- a/Timelapse_keyboard/GPS.c
+++ b/Timelapse_keyboard/GPS.c
@@ -155,7 +155,8 @@ void GPS_parse_answer(uint8_t *buf){
 	*ptr++ = 0;
 	if(*ptr == 'A'){
 		GPS_status = GPS_VALID;
-		set_time(buf);
-	}else
+	}else{
 		GPS_status = GPS_NOT_VALID;
+	}
+	set_time(buf);
 }
diff --git a/Timelapse_keyboard/Makefile b/Timelapse_keyboard/Makefile
index 821ad23..5c38f09 100644
--- a/Timelapse_keyboard/Makefile
+++ b/Timelapse_keyboard/Makefile
@@ -1,8 +1,7 @@
 BINARY		= timelapse
 BOOTPORT	?= /dev/ttyUSB0
 BOOTSPEED	?= 115200
-# change this linking script depending on particular MCU model,
-# for example, if you have STM32F103VBT6, you should write:
+# change this linking script depending on particular MCU model
 LDSCRIPT	= ld/stm32f103x8.ld
 LIBNAME		= opencm3_stm32f1
 # add -DULTRASONIC to compile with ultrasonic distance-meter support
diff --git a/Timelapse_keyboard/hardware_ini.h b/Timelapse_keyboard/hardware_ini.h
index fb497b7..c207f77 100644
--- a/Timelapse_keyboard/hardware_ini.h
+++ b/Timelapse_keyboard/hardware_ini.h
@@ -35,15 +35,15 @@
 void GPIO_init();
 void SysTick_init();
 
-// yellow LEDs: PA11, PA12
+// yellow LEDs: PA11, PA12; Y1- - trigr, Y2 - PPS
 #define LEDS_Y_PORT      GPIOA
 #define LEDS_Y1_PIN      GPIO13
 #define LEDS_Y2_PIN      GPIO15
-// green LEDs: PB7, PB8
+// green LEDs: PB7, PB8; G1 - GPS rdy
 #define LEDS_G_PORT      GPIOB
 #define LEDS_G1_PIN      GPIO7
 #define LEDS_G2_PIN      GPIO8
-// red LEDs: PB6, PB5
+// red LEDs: PB6, PB5; R2 - power
 #define LEDS_R_PORT      GPIOB
 #define LEDS_R1_PIN      GPIO6
 #define LEDS_R2_PIN      GPIO5
diff --git a/Timelapse_keyboard/main.c b/Timelapse_keyboard/main.c
index c125220..6986362 100644
--- a/Timelapse_keyboard/main.c
+++ b/Timelapse_keyboard/main.c
@@ -65,7 +65,8 @@ void time_increment(){
 }
 
 int main(void){
-	uint8_t *string, *lastGPSans = NULL; // string from UART2 & pointer to last full GPS answer
+	uint8_t *string; // string from UART2 & pointer to last full GPS answer
+	uint8_t lastGPSans[UART_BUF_DATA_SIZE] = {0};
 	int i;
 	rcc_clock_setup_in_hse_8mhz_out_72mhz();
 	// init systick (1ms)
@@ -107,6 +108,8 @@ int main(void){
 	iwdg_set_period_ms(50); // set watchdog timeout to 50ms
 	iwdg_start();
 	while(1){
+		if(Timer == 500) // turn off PPS LED after 500ms
+			gpio_set(LEDS_Y_PORT, LEDS_Y2_PIN);
 		poll_usbkeybrd();
 		if(usbkbrdtm != msctr){ // process USB not frequently than once per 1ms
 			process_usbkbrd();
@@ -117,7 +120,7 @@ int main(void){
 		#endif
 		poll_ADC();
 		if((string = check_UART2())){
-			lastGPSans = string;
+			memcpy(lastGPSans, string, UART_BUF_DATA_SIZE);
 			GPS_parse_answer(string);
 		}
 /*
@@ -149,7 +152,7 @@ if(msctr - trigrtm > 3000){
 				istriggered = 1;
 				P("Button time: ");
 				print_time(&trigger_time, trigger_ms);
-				if(lastGPSans){
+				if(*lastGPSans){
 					P("GPS last message: ");
 					send_msg((char*)lastGPSans);
 					newline();
@@ -221,11 +224,12 @@ if(msctr - trigrtm > 3000){
 		}
 		// check GPS status to turn on/off GPS LED
 		if(current_time.H < 24){ // timer OK
-			if(GPS_status != GPS_VALID || need_sync)
+			if((GPS_status != GPS_VALID) || need_sync){
 				GPSLEDblink = 1;
-			else if(GPSLEDblink){
+			}else{
 				GPSLEDblink = 0;
-				gpio_clear(LEDS_G_PORT, LEDS_G1_PIN); // turn ON G1 LED
+				if((GPIO_ODR(LEDS_G_PORT) & LEDS_G1_PIN) == 0)
+					gpio_clear(LEDS_G_PORT, LEDS_G1_PIN); // turn ON G1 LED
 			}
 			if(GPSLEDblink){
 				if(msctr - GPSstatus_tm > 500 || msctr < GPSstatus_tm){
@@ -268,6 +272,7 @@ void exti4_isr(){
 	uint32_t t = 0, ticks;
 	static uint32_t ticksavr = 0, N = 0;
 	if(EXTI_PR & EXTI4){
+		gpio_clear(LEDS_Y_PORT, LEDS_Y2_PIN);
 		// correct
 		systick_val = STK_CVR;
 		STK_CVR = RVR0;
diff --git a/Timelapse_keyboard/timelapse.bin b/Timelapse_keyboard/timelapse.bin
index fe2eca1..80acb08 100755
Binary files a/Timelapse_keyboard/timelapse.bin and b/Timelapse_keyboard/timelapse.bin differ