# ESP32 suddenly not recognising I2C devices **URL:** \ **Category:** Uncategorized\ **Created:** [22 June 2024 19:17 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308 "2024-06-22T19:17:03Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Jacob213709](https://avatars.discourse-cdn.com/v4/letter/j/35a633/32.png) [@Jacob213709](https://forum.core-electronics.com.au/u/Jacob213709)\ **Post date:** [22 June 2024 19:17 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/1 "2024-06-22T19:17:03Z")
My ESP32 Thing Plus’s (I have 2) are not recognising any I2C devices all of a sudden, specifically ZED-F9P boards, but I’ve tried several magnetometers too with the same problem. The Arduino IDE ESP32 Board package was updated 3 days ago, so I don’t know if that has anything to do with it, but using older versions does not seem to fix the issue. Up until a few days ago, I was able to connect a [ZED-F9P board](https://core-electronics.com.au/sparkfun-gps-rtk-sma-breakout-zed-f9p-qwiic.html) via Qwiic cable to an [ESP32 Thing Plus](https://core-electronics.com.au/sparkfun-thing-plus-esp32-wroom-usb-c.html), upload an [example sketch](https://github.com/sparkfun/SparkFun_u-blox_GNSS_v3/blob/main/examples/ZED-F9P/Example17_NTRIPClient_With_GGA_Callback/Example17_NTRIPClient_With_GGA_Callback.ino), and have a working RTK GPS device. This no longer works, and I have no idea why. I’m pretty sure I’m not doing anything different. All I see is: “u-blox GPS not detected at default I2C address. Please check wiring.” Any ideas? 🙂 ---
**Author:** ![Pixmusix](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/pixmusix/32/9719_2.png) [@Pixmusix](https://forum.core-electronics.com.au/u/Pixmusix)\ **Post date:** [23 June 2024 06:56 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/2 "2024-06-23T06:56:38Z")
@Jeff105671 taught me how to use a i2c scanner I found very helpful while debugging. > [@Adafruit Py Qt 2040 - Thonny - Piicodev](https://forum.core-electronics.com.au/t/adafruit-py-qt-2040-thonny-piicodev/20043/5): > > Ah I see it’s a python library not a Linux package. Thanks for the link +1 Based on the [pinout of the qt py](https://learn.adafruit.com/adafruit-qt-py-2040/pinouts) I have two i2c outs so I modified the code you linked to search both of them. from machine import Pin, SoftI2C def scani2c(i2c): devices = i2c.scan() if len(devices) == 0: print("No i2c device !") else: print('i2c devices found:', len(devices)) for device in devices: print("I2C hexadecimal address: ", hex(device)) i2c\_0 = SoftI2C(scl=Pin(25), sd… ---
**Author:** ![Robert93820](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@Robert93820](https://forum.core-electronics.com.au/u/Robert93820)\ **Post date:** [23 June 2024 09:32 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/3 "2024-06-23T09:32:32Z")
Hi Jacob > [@Jacob213709](#): > > Please check wiring.” Have you done that. Not only a visual but the integrity of any wire jumper links themselves. Also breadboard connections if you are using them. It is not unknown for even pre-made links to have faulty crimps etc. A few years ago there was a contributor who had a problem and had tried absolutely everything except the actual wires. I suggested he replace ALL wire jumper links and the problem went away. Needless to say my next suggestion was to bin ALL of these to get the faulty one or more out of circulation. If your system has worked once and you have done nothing it should work again. Unless somehow some memory or something has filled up and will no longer accept information. Don’t know about that one. Cheers Bob ---
**Author:** ![lia262073](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@lia262073](https://forum.core-electronics.com.au/u/lia262073)\ **Post date:** [23 June 2024 19:10 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/4 "2024-06-23T19:10:37Z")
I’ll suggest you try the I2C scanner code. Try with any other I2C device except the U-blox GPS. Since the problem occurred after updating ESP32 Board package, you can try it in another computer. Here I also found a similar issue. > **[ESP32 board will not recognize I2C devices - ESP32 Forum](https://esp32.com/viewtopic.php?t=26019)** > > Espressif ESP32 Official Forum ---
**Author:** ![Jacob213709](https://avatars.discourse-cdn.com/v4/letter/j/35a633/32.png) [@Jacob213709](https://forum.core-electronics.com.au/u/Jacob213709)\ **Post date:** [23 June 2024 21:35 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/5 "2024-06-23T21:35:10Z")
Solved: I had selected “ESP32 Thing Plus” instead of the correct board “ESP32 Thing Plus C” as my device in the Arduino IDE. Now that I’ve selected “ESP32 Thing Plus C” it is working. I have a single-digit IQ I just found this out by accident, and I wouldn’t have got there on purpose because I actually thought the “Thing Plus” and the “Thing Plus C” were the same board with different USB port types (Thing Plus has a Micro-B port). Looks like the [“Thing Plus C”](https://www.sparkfun.com/products/retired/18018) was retired and is now called a “Thing Plus - ESP32 WROOM (USB-C)” which appears to work differently to a “Thing Plus - ESP32 WROOM (Micro-B)”. ---
**Author:** ![Aaron](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/aaron/32/9861_2.png) [@Aaron](https://forum.core-electronics.com.au/u/Aaron)\ **Post date:** [24 June 2024 03:45 UTC](https://forum.core-electronics.com.au/t/esp32-suddenly-not-recognising-i2c-devices/20308/6 "2024-06-24T03:45:24Z")
Glad to hear you got it working @Jacob213709!!!