const int ledPin = 12; int blinkRate=0; int ledState = 0; void setup() { Serial.begin(9600); pinMode(ledPin, OUTPUT); } void loop() { if ( Serial.available()) { char ch = Serial.read(); if (ch >= '0' && ch <= '9') { blinkRate = ch - '0'; } } ledState = 1 - ledState; digitalWrite(ledPin, ledState); delay(blinkRate * 100); }