Photon I2C bus issues

It appears that the latest shipment of Photons has issues with I2C. I am using the SparkFun Photon Wether Shield and can not get valid data from the humidity, temperature or pressure sensors. Apparently, Core does work properly with the SparkFun Weather Shield but not with Photon.

@wmjenk, the latest 0.4.3rc2 release of the system firmware fixes these issues. If you want to flash this version onto your Photon, look here. :grinning:

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I was having problems with the BMP085 example - all sorted now with the new firmware revision. Thanks !


Thanks for the suggestion. I did successfully flash my new Photon with 0.4.3rc2 of the firmware. I reloaded the SparkFun Photon Weather Shield basic example (temperature, humidity,pressure, altitude readout) and I am still getting bogus data: Temp:31.10F, Humidity: 998.00%, Pressure:-999.00PA, Altitude:-327.56ft.
The Photon I am using is from the latest shipping run and the issue has been replicated by SparkFun engineers. They indicated the issue occurred previously prior to release of their weather board but fixed by Particle. They confirm it is now happening again but not with Core only Photon. Apparently the issue has returned with the latest Photon. I presume there needs to be a further firmware update as currently I2C functionality with the latest Photons appears non-functional. I hope there is a fix soon.

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I double checked the OTA update and made sure I updated both part 1 and part 2. I then re-ran the SparkFun basic example. It provided the following serial output:
Temp:83.01, Humidity:47.94,Pressure:452.00Pa, Altitude:370.94ft
Temp:31.01F, Humidity:998.00%, Pressure:-999.00Pa, Altitude:-3277.56ft.

and then continued with the bogus data after 4 readouts of more reasonable temperature etc. Subsequent flashing of the basic program now yields only the bogus temperature/hum/pressure readings.

@wmjenk, I have a Sparkfun weather shield and I’ll be looking at this issue this weekend :smile:

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Great, thanks. Joel Bartlett (author of the weather shield setup guide) at Sparkfun replicated the issue on Photon but the code works fine on Core. He thinks it is a firmware issue.

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@wmjenk, just realized that the sparkfun shield I have defaults to using the onboard regulator and an external power supply. This explains why the I2C stuff doesn’t work - NO POWER when I use the Core/Photon USB!!! I will fix the jumper and report back.

@wmjenk, yup that was the problem as least with the Core. I will be testing the Photon later (after I go see Ant Man!).

Enjoy Ant Man! BTW, I have my Photon powered from the Photon USB not an external supply

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@peekay123, any luck replicating the I2C issue with a Photon and the SparkFun Photon Weather Shield?

I would like to try out a theory since I don’t have the weather shield to test on at present. If there is someone who has a weather shield and is able to test out a possible fix, please PM me an email address and I’ll send some updated system binaries. Thanks! :smile:

Hey William,

Reading your Zendesk ticket now on this same issue, and I believe this is definitely something I can have a conversation about and find better solutions to, with our other engineers.

@mdma and I will speak on this soon enough.


@corey, @mdma,@BDub, any update on a fix for the I2C problems on the Photon with the SparkFun Photon Weather Board? I reported the issue to both SparkFun and Particle seven days ago. I would be happy to test any proposed fix. Thank you!\

@wmjenk, I am having issue with the jumpers on the board so I can power it properly. I will be testing again tonight with both the latest release firmware and the develop :smile:

That would be great, looking forward to your test results. Thanks! smile

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Hey @wmjenk,

We are still looking into this issue for you and the community. Please stay patient as we troubleshoot this issue :smile: .

Also, feel free to post any possible solutions that you may come across in the meantime.


Patient, I am. Thank you.

A new release candidate is available for download that fixes these issues. :smile: Particle Firmware Updates Thread

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I was able to use the particle flash command to successfully update two of my Photons, both of them appear to work correctly with SparkFun Photon Weather Shield (although temp seems high and barometric pressure seems low–more testing). Note I was not able to use the particle flash command on two other Photons, both reported flash device failed-also some weirdness after trying the particle flash command as devices appeared offline when doing a list after the flash device failed. I was able to update both of these Photons using the dfu-util update instructions found here:

All of my Photons appear to be working but I need to check all against I2C functionality and get to the bottom of the high temp/low barometric readings on the SparkFun Photon Weather Shield.
Thanks for all the hard work that went into this update, much appreciated! :+1:

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