diff --git a/flix/flix.ino b/flix/flix.ino
index ef270ad..cbf9671 100644
--- a/flix/flix.ino
+++ b/flix/flix.ino
@@ -35,14 +35,10 @@ Vector acc; // accelerometer data, m/s/s
 Quaternion attitude; // estimated attitude
 bool calibrating; // flag we're calibrating
 
-void setupDebug();
-void lowPowerMode();
-
 void setup()
 {
 	Serial.begin(SERIAL_BAUDRATE);
 	Serial.println("Initializing flix");
-	setupTime();
 	setupLED();
 	setupMotors();
 	setLED(true);
diff --git a/flix/imu.ino b/flix/imu.ino
index 7b99cec..9c74121 100644
--- a/flix/imu.ino
+++ b/flix/imu.ino
@@ -59,7 +59,7 @@ static void calibrateGyro()
 	Serial.println("Calibrating gyro, stand still");
 	delay(500);
 	int status = IMU.calibrateGyro();
-	Serial.println("Calibration status: " + String(status));
+	Serial.printf("Calibration status: %d\n", status);
 	Serial.print("Gyro bias: ");
 	Serial.print(IMU.getGyroBiasX_rads(), 10); Serial.print(" ");
 	Serial.print(IMU.getGyroBiasY_rads(), 10); Serial.print(" ");
diff --git a/flix/led.ino b/flix/led.ino
index 1884202..4815a97 100644
--- a/flix/led.ino
+++ b/flix/led.ino
@@ -1,18 +1,7 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
-#define LED_PIN 2
-#define BLINK_FAST_PERIOD 300000
-#define BLINK_SLOW_PERIOD 1000000
-
-static bool state;
-
-static enum {
-	OFF,
-	ON,
-	BLINK_FAST,
-	BLINK_SLOW
-} LEDscheme = OFF;
+#define BLINK_PERIOD 500000
 
 void setupLED()
 {
@@ -24,20 +13,7 @@ void setLED(bool on)
 	digitalWrite(LED_BUILTIN, on ? HIGH : LOW);
 }
 
-void proceedLED()
-{
-	// TODO: this won't work
-	// TODO:: just check is current second even or odd
-	if (LEDscheme == BLINK_FAST && stepTime % BLINK_FAST_PERIOD == 0) {
-		state != state;
-		digitalWrite(LED_BUILTIN, state ? HIGH : LOW);
-	} else if (LEDscheme == BLINK_SLOW && stepTime % BLINK_SLOW_PERIOD == 0) {
-		state != state;
-		digitalWrite(LED_BUILTIN, state ? HIGH : LOW);
-	}
-}
-
 void blinkLED()
 {
-	setLED(micros() / 500000 % 2);
+	setLED(micros() / BLINK_PERIOD % 2);
 }
diff --git a/flix/pid.hpp b/flix/pid.hpp
index 16fc76a..5a16bc7 100644
--- a/flix/pid.hpp
+++ b/flix/pid.hpp
@@ -1,6 +1,8 @@
 // Copyright (c) 2023 Oleg Kalachev <okalachev@gmail.com>
 // Repository: https://github.com/okalachev/flix
 
+// PID controller implementation
+
 #pragma once
 
 class PID
diff --git a/flix/time.ino b/flix/time.ino
index 0dca65e..5830ea1 100644
--- a/flix/time.ino
+++ b/flix/time.ino
@@ -7,11 +7,6 @@ const uint32_t S = 1000000;
 static uint32_t stepsPerSecondCurrent;
 static uint32_t stepsPerSecondCurrentLast;
 
-void setupTime()
-{
-	startTime = micros();
-}
-
 void step() {
 	steps++;
 	auto time = micros();
diff --git a/flix/util.ino b/flix/util.ino
index 80e1c6b..c9b9f1f 100644
--- a/flix/util.ino
+++ b/flix/util.ino
@@ -13,11 +13,6 @@ float mapff(float x, float in_min, float in_max, float out_min, float out_max)
 	return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
 }
 
-// float hypot3(float x, float y, float z)
-// {
-// 	return sqrt(x * x + y * y + z * z);
-// }
-
 int8_t sign(float x)
 {
 	return (x > 0) - (x < 0);
@@ -28,19 +23,4 @@ float randomFloat(float min, float max)
 	return min + (max - min) * (float)rand() / RAND_MAX;
 }
 
-// === printf ===
-// https://github.com/jandelgado/log4arduino/blob/master/src/log4arduino.cpp#L51
-// https://webhamster.ru/mytetrashare/index/mtb0/16381244680p5beet5d6
-
-#ifdef ARDUINO
-#define PRINTF_MAX_STRING_LEN 200
-void printf(const __FlashStringHelper *fmt, ...)
-{
-	char buf[PRINTF_MAX_STRING_LEN];
-	va_list args;
-	va_start(args, fmt);
-	vsnprintf(buf, PRINTF_MAX_STRING_LEN, (PGM_P)fmt, args);
-	va_end(args);
-	Serial.print(buf);
 }
-#endif
diff --git a/flix/wifi.ino b/flix/wifi.ino
index c64ed4b..3832859 100644
--- a/flix/wifi.ino
+++ b/flix/wifi.ino
@@ -3,6 +3,7 @@
 
 // https://github.com/espressif/arduino-esp32/blob/master/libraries/WiFi/examples/WiFiAccessPoint/WiFiAccessPoint.ino
 // https://github.com/espressif/arduino-esp32/blob/master/libraries/WiFi/examples/WiFiClient/WiFiClient.ino
+// https://github.com/espressif/arduino-esp32/blob/master/libraries/WiFi/examples/WiFiUDPClient/WiFiUDPClient.ino
 
 #if WIFI_ENABLED == 1