I am trying to send TTL pulse at 1second interval to Raspberry pi? Can someone suggest me a good way to do it using GPIO or any other way possible.

Arduino Code:

void setup() {
    pinMode(12, OUTPUT);

void loop() {
    digitalWrite(12, HIGH);   // turn the LED on (HIGH is the voltage level)
    delay(1000);                       // wait for a second
    digitalWrite(12, LOW);    // turn the LED off by making the voltage LOW
    delay(1000);                       // wait for a second

Raspberry Pi Code:

import RPi.GPIO as GPIO
import time

pinTTL = 4

GPIO.setup(pinTTL, GPIO.IN)

start_time = time.time()
t_end = start_time + 60
while time.time()<t_end:
    inputState = GPIO.input(pinTTL)
    if inputState == True:
        print 'HIGH', time.time() - start_time
        print 'LOW', time.time() - start_time


Another thing is I have checked using multimeter, the voltage on Pi output pin does change at 1second interval.

  • What have you tried? Where is your Arduino code? Where is your Pi code? How have you dropped the Arduino 5V GPIO to a Pi safe 3V3?
    – joan
    Jan 22, 2017 at 10:45
  • I have dropped the 5v arduino output to 3.3v for making it safe for Pi. I just used a normal arduino code for setting the pin output high and low at 1second interval to see if this works and whether the raspberry pi input pin detects that but I coulnd't get it work
    – raj
    Jan 22, 2017 at 14:33
  • Edit your question and include the Arduino and Pi code you are using.
    – joan
    Jan 22, 2017 at 14:57
  • added the scripts
    – raj
    Jan 26, 2017 at 6:02
  • Presumably you haven't connected the correct Arduino pin to the correct Pi pin. Please add a photo. abyz.co.uk/rpi/pigpio/index.html#Type_3 shows the position of GPIO4 on pin 7.
    – joan
    Jan 26, 2017 at 9:12

1 Answer 1


The problem lied somewhere in connection only. Changing the pinTTL=6 solved the problem.

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