# PiicoDev could not communicate with module at address 0x3C, check wiring **URL:** \ **Category:** Raspberry Pi\ **Created:** [23 April 2023 04:37 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906 "2023-04-23T04:37:28Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [23 April 2023 04:37 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/1 "2023-04-23T04:37:28Z")
Hi looking to get some help with the error PiicoDev could not communicate with module at address 0x3C, check wiring I’m trying to wire in a PiicDev OLED Module SSD1306, but the cable connector on the end of Piico Dev adapter snapped off ☹ , so I’m wiring directly to pin on the PiicDev expander board. I have downloaded code in the video, I have the break-out cable with the pins pulled into the OLED module. I have red lead in pin 5 3VC, black in pin 3 GND, and blue in pin 8 SCL and yellow in pin 9 SCL. The OLED ASW set to Off. The green led on the back lights up when I run the code cheer David ---
**Author:** ![Liam120347](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/liam120347/32/5003_2.png) [@Liam120347](https://forum.core-electronics.com.au/u/Liam120347)\ **Post date:** [23 April 2023 04:49 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/2 "2023-04-23T04:49:48Z")
Hi David, Would it be possible to attach a photo of everything connected? That setup should work, I’d check pins 8 and 9 relate to the GPIO numbers rather than the physical pins. ---
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [23 April 2023 05:05 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/3 "2023-04-23T05:05:24Z")
cheers thanks Liam, ![20230423_145903](https://canada1.discourse-cdn.com/flex028/uploads/core_electronics/original/2X/d/d11bcc7cc2b764839fcb37836d3926f8ed744e86.jpeg) ---
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [23 April 2023 05:14 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/4 "2023-04-23T05:14:08Z")
I re read, the first post, I got the pin’s info wrong slaps heads This is what I have now … Blue in pin marked SCL - 9 Yellow in pin marked SDA 8 The green led on the OLED module turns on, but the same “PiicoDev could not communicate with module at address 0x3C, check wiring” message ![20230423_1507431](https://canada1.discourse-cdn.com/flex028/uploads/core_electronics/original/2X/8/8e25ffc2eba04aedf9d4c9e21381948d5c8d7a20.jpeg) ---
**Author:** ![Liam120347](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/liam120347/32/5003_2.png) [@Liam120347](https://forum.core-electronics.com.au/u/Liam120347)\ **Post date:** [23 April 2023 06:36 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/5 "2023-04-23T06:36:16Z")
Hi David, Sorry, Blue (SDA) is correct in pin 8 and Yellow (SCL) is correct in 9. Everything should be working as intended with this setup. If you run the following in the REPL whats the response? ```auto from machine import I2C i2c = I2C(0) i2c.scan() ``` ---
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [23 April 2023 07:01 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/6 "2023-04-23T07:01:52Z")
> [@Liam120347](#): > > ```auto > from machine import I2C > i2c = I2C(0) > i2c.scan() > > ``` OK, done Blue in SDA Pin 8 Yellow in SCL Pin 9 Bellow is the result of scan > > > from machine import I2C > > > i2c = I2C(0) > > > i2c.scan() > > > [60] ---
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [23 April 2023 07:05 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/7 "2023-04-23T07:05:02Z")
Ok ran the sample code. No green LED, No errors. No display. If I hit Stop on Thonny if gives a Unable to coonect on com port 4. I have to reset the Ras Pi ---
**Author:** ![James](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/james/32/4400_2.png) [@James](https://forum.core-electronics.com.au/u/James)\ **Post date:** [24 April 2023 01:53 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/8 "2023-04-24T01:53:35Z")
Hi David, If you’re getting back 60 in your scan, that’s decimal for 0x3C, so your connections are right, I think it could possibly be something wrong with your code, could you double click on the `main.py` file in Thonny and paste its contents in here? Just want to rule out errors there. Keen to get to the bottom of this one! ---
**Author:** ![David47467](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/david47467/32/8301_2.png) [@David47467](https://forum.core-electronics.com.au/u/David47467)\ **Post date:** [24 April 2023 05:13 UTC](https://forum.core-electronics.com.au/t/piicodev-could-not-communicate-with-module-at-address-0x3c-check-wiring/16906/9 "2023-04-24T05:13:12Z")
Cheers, thanks to all who are helping on this. It gets stranger. I replugged it all in again and ran the code again (this is the demo code from the OLED site) and it started to run the demo. 😵‍💫 ![20230424_150449](https://canada1.discourse-cdn.com/flex028/uploads/core_electronics/original/2X/3/354428209d4a12a6e052a7e8f9a1c71192f03394.jpeg) The only thing I can think of is the plug wasn’t seated all the way, this feels right up there with turning it “off and on again”. I will keep on with the demo code, but at the moment it seems to work. Thanks again to the clever people in the forum.