https://youtu.be/9qv9F0zIUgI

An Arduino controlled chess clock. The speed of the clock can be changed with a potentiometer. High speed for reaction games. t is the delay after each change of levels and allows the magnetic fields to build up properly. t=3 works for most stepper motors. Make sure your power supply is accurate and supplies 5 volts, 1 or 2 Amps. The Arduino sketch below makes it all work.

//Nano half step mode //512 >> 360 degrees 1.4 step/degree int Pin0 = 9; int Pin1 = 10; int Pin2 = 11; int Pin3 = 12; int Pin4 = 2; int Pin5 = 3; int Pin6 = 4; int Pin7 = 5; int ClockPin = 2; //change between the two clocks int SpeedPin = 0; //adjust with the potentiometer int t=3; void setup() { pinMode(Pin0, OUTPUT); pinMode(Pin1, OUTPUT); pinMode(Pin2, OUTPUT); pinMode(Pin3, OUTPUT);
pinMode(Pin4, OUTPUT); pinMode(Pin5, OUTPUT); pinMode(Pin6, OUTPUT); pinMode(Pin7, OUTPUT); pinMode(ClockPin, INPUT); pinMode(SpeedPin, INPUT); } void loop() { int val = analogRead(ClockPin); int speed = analogRead(SpeedPin); if(val<400){ digitalWrite(Pin0, LOW); digitalWrite(Pin1, LOW); digitalWrite(Pin2, LOW); digitalWrite(Pin3, HIGH); delay(t); digitalWrite(Pin0, LOW); digitalWrite(Pin1, LOW); digitalWrite(Pin2, HIGH); digitalWrite(Pin3, HIGH); delay(t); digitalWrite(Pin0, LOW); digitalWrite(Pin1, LOW); digitalWrite(Pin2, HIGH); digitalWrite(Pin3, LOW); delay(t); digitalWrite(Pin0, LOW); digitalWrite(Pin1, HIGH); digitalWrite(Pin2, HIGH); digitalWrite(Pin3, LOW); delay(t); digitalWrite(Pin0, LOW); digitalWrite(Pin1, HIGH); digitalWrite(Pin2, LOW); digitalWrite(Pin3, LOW); delay(t); digitalWrite(Pin0, HIGH); digitalWrite(Pin1, HIGH); digitalWrite(Pin2, LOW); digitalWrite(Pin3, LOW); delay(t); digitalWrite(Pin0, HIGH); digitalWrite(Pin1, LOW); digitalWrite(Pin2, LOW); digitalWrite(Pin3, LOW); delay(t); digitalWrite(Pin0, HIGH); digitalWrite(Pin1, LOW); digitalWrite(Pin2, LOW); digitalWrite(Pin3, HIGH); delay(t); delay(speed);} else{ digitalWrite(Pin4, LOW); digitalWrite(Pin5, LOW); digitalWrite(Pin6, LOW); digitalWrite(Pin7, HIGH); delay(t); digitalWrite(Pin4, LOW); digitalWrite(Pin5, LOW); digitalWrite(Pin6, HIGH); digitalWrite(Pin7, HIGH); delay(t); digitalWrite(Pin4, LOW); digitalWrite(Pin5, LOW); digitalWrite(Pin6, HIGH); digitalWrite(Pin7, LOW); delay(t); digitalWrite(Pin4, LOW); digitalWrite(Pin5, HIGH); digitalWrite(Pin6, HIGH); digitalWrite(Pin7, LOW); delay(t); digitalWrite(Pin4, LOW); digitalWrite(Pin5, HIGH); digitalWrite(Pin6, LOW); digitalWrite(Pin7, LOW); delay(t); digitalWrite(Pin4, HIGH); digitalWrite(Pin5, HIGH); digitalWrite(Pin6, LOW); digitalWrite(Pin7, LOW); delay(t); digitalWrite(Pin4, HIGH); digitalWrite(Pin5, LOW); digitalWrite(Pin6, LOW); digitalWrite(Pin7, LOW); delay(t); digitalWrite(Pin4, HIGH); digitalWrite(Pin5, LOW); digitalWrite(Pin6, LOW); digitalWrite(Pin7, HIGH); delay(t); delay(speed);} }