# I2C error encountered during I2C transmit hook execution

**URL:** <https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019>\
**Category:** Troubleshooting\
**Created:** [May 1, 2025, 9:14am UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019 "2025-05-01T09:14:51Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Srihari](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@Srihari](https://discuss.blues.com/u/Srihari)\
**Post date:** [May 1, 2025, 9:14am UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/1 "2025-05-01T09:14:52Z")

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@RobLauer I have been using notecard for one year and facing I2C errors since 2 days.  
I don’t see data in Notehub and not whether it is issue with ESP32S3 MCU or Notecard.

I tried sample sketch “Example1\_NotecardBasics.ino” and see below errors.

14:30:47.605 → [ERROR] error encountered during I2C transmit hook execution

14:30:48.599 → [ERROR] i2c: received NACK on transmit of address {io}

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**Author:** ![tjvantoll](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/tjvantoll/32/231_2.png) [@tjvantoll](https://discuss.blues.com/u/tjvantoll)\
**Post date:** [May 1, 2025, 2:05pm UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/2 "2025-05-01T14:05:58Z")

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Hey @Srihari,

Sorry you ran into issues here. Could you show us how you have your Notecard and MCU connected? And also could you let us know what version of Notecard firmware you’re using?

Thanks,  
TJ

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<div class="post-metadata">

**Author:** ![Srihari](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@Srihari](https://discuss.blues.com/u/Srihari)\
**Post date:** [May 2, 2025, 6:16am UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/3 "2025-05-02T06:16:20Z")

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![image](https://us1.discourse-cdn.com/flex020/uploads/blues/original/2X/4/4cfc8fdeb3052a6739c4b925666cfecd8fbd788b.png)

 ![image](https://us1.discourse-cdn.com/flex020/uploads/blues/original/2X/7/716ab17b392a5758e87e8558928e45bc685946bf.png)

It seems to be nothing communicating and tried to reset. I think the notecard not responding on the I2C.

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**Author:** ![tjvantoll](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/tjvantoll/32/231_2.png) [@tjvantoll](https://discuss.blues.com/u/tjvantoll)\
**Post date:** [May 2, 2025, 7:03pm UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/4 "2025-05-02T19:03:44Z")

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Could you show me a picture of the physical Notecard and how you have your host connected? Using I2C errors are related to that.

Also you might want to try restarting your device to see if that helps solve the problem.

TJ

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<div class="post-metadata">

**Author:** ![Srihari](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@Srihari](https://discuss.blues.com/u/Srihari)\
**Post date:** [May 3, 2025, 7:38am UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/5 "2025-05-03T07:38:18Z")

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It was worked before and haven’t changed hardware connections.  
I also upgrade Notecard firmware to latest through USB connection.  
I will share the connections through email once my organization ok to share it as per org polices.

16:44:32.160 → Constructing Payload message  
16:44:32.160 → [INFO] {“req”:“note.add”,“sync”:true,“body”:{“ts”:1746184472,“altitude”:154.5,“speed”:1,“geofence”:“US”,“latitude”:18.5786845,“longitude”:83.365817333,“locationNumber”:78,“tripCounter”:372,“MessageType”:“Track”},“file”:“track.qo”,“full”:true,“crc”:“0063:7E01A41B”}  
16:44:32.197 → E (558050) i2c.master: I2C hardware NACK detected  
16:44:32.277 → E (558100) i2c.master: s\_i2c\_synchronous\_transaction(924): I2C transaction failed  
16:44:32.277 → E (558100) i2c.master: i2c\_master\_multi\_buffer\_transmit(1186): I2C transaction failed  
16:44:32.277 → [ERROR] i2c: unknown error on TwoWire::endTransmission() {io}

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<div class="post-metadata">

**Author:** ![tjvantoll](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/tjvantoll/32/231_2.png) [@tjvantoll](https://discuss.blues.com/u/tjvantoll)\
**Post date:** [May 5, 2025, 1:50pm UTC](https://discuss.blues.com/t/i2c-error-encountered-during-i2c-transmit-hook-execution/3019/6 "2025-05-05T13:50:44Z")

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As another thought, have you updated your ESP32 BSP (Board Support Package) or `note-arduino` version?

And if you can’t publicly post the pictures of your hardware, you can DM me or email me ([tvantoll@blues.com](mailto:tvantoll@blues.com)) and we can continue the conversation there.

Thanks,  
TJ