Logic Level not pushing 3.3v

Other Hardware General Electronics
1

I am using an Arduino to control my RaspberryPi. I want to send a high and low signal from pin 2 on my Arduino to pin 12 on my Raspberry Pi. Based on that high signal my raspberry pi would run a python program. Since Arduino is a 5v system and raspberry pi is a 3.3v system I got a logic level to transfer the high/low signal between the two boards. I’ve set it up as follows:

9v —> Arduino VIN
Arduino 5v —> Hv
Arduino GND —> GND
Arduino 3.3v —> Lv
Arduino GND —> GND
Arduino Pin2 —> H1
RaspberryPi Pin12 —> L1

In order to test the Arduino and setup I programmed the Arduino to pull up and down the pin every 3 seconds. I did a voltage test on Pin2 and it pulled up at 5v and down to just over 1v; however, when I do a voltage test on L1 it never really gets above about 0.55v and it never really goes below 0.53v. Regardless it’s a long way from 3.3v. I’ve looked up everything and check a ton of times. It looks like I have everything connected correctly so I’m at a loss. I bought a couple logic levels so I tried a different one with exactly the same results. Clearly I’m missing something but I’m at a loss as to what that is. I’ve never used a logic level before. Thanks for any guidance people can suggest.

2

You didn't say WHICH level shifter but I believe this should work:

9v --> Arduino VIN
Arduino 5v --> Hv
Arduino GND --> GND
Pi 3.3v --> Lv
Pi GND --> GND
Arduino Pin2 --> H1
RaspberryPi Pin12 --> L1

3

Logic Level Used:

4

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .

You do have gnd of the Arduino and the Pi connected together?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks Tom... :slight_smile: