Azure Sphere Secure IOT - I2C Compass

RE: Azure Sphere Secure IOT - I2C Compass

-manu- — Thu, 13 Dec 2018 18:12:41 GMT

Andy,

Thanks for sharing your I2C bit-banging on Azure Sphere work. Like you, we are frustrated with the lack of native I2C support on the MT3620. Once your software emulation works, we will all be able to proceed knowing that we can switch to the native support whenever it comes.

RE: Azure Sphere Secure IOT - I2C Compass

shabaz — Sun, 09 Dec 2018 01:12:08 GMT

Hi Andy,

If you're running this on a laptop, it could be worth unplugging it from the PSU temporarily, just to check if it is being caused by current through the ground connection.

Also, it's a pain when APIs use High and Low for open drain, because it's never completely clear if the high means floating high, or pulled to ground (because in open drain, when the signal is asserted, it is pulled low, whereas with normal push-pull, when it is asserted, it is pulled high). So it is easier if they'd use the term asserted.

But it sounds like you've already checked that since you connected an LED. And if you've stepped through the code it seems like all is well there.. I think it could be worth replacing the 10k with 2.2k, just in case the load is too high.

RE: Azure Sphere Secure IOT - I2C Compass

Workshopshed — Sun, 09 Dec 2018 00:12:28 GMT

I tried to use the PicoScope 2204A to decode the I2C protocol but the scope keeps overloading my USB bus. I was hoping that using a powered hub would solve my problems with the picoscope but it appears not, I did manage to get one trace which reflected what I was getting back in my debug window and the address for read and write seemed good but that got lost before I could snapshot it.

So I added some LEDs to the data lines and a push switch from the SDA line to GND. I stepped through the code using the switch to behave as the remote, cross referencing against these two links. And the code does seem to be valid.

RE: Azure Sphere Secure IOT - I2C Compass

DAB — Sat, 24 Nov 2018 20:08:20 GMT

Nice update.

I know how it is when work interferes with fun.

DAB