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FONA Sim5320A SDA SCL pins?
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FONA Sim5320A SDA SCL pins?

by Hiraghm on Thu Nov 07, 2019 6:04 pm

Looking over my FONA Sim5320A (3G), I noticed a couple of holes right next to the antennas labeled "SDA" and "SCL"... does this mean the FONA is capable of I2C communication?

I'm looking for faster / more reliable ways to talk to my FONA from my Pi, without tying up a USB port. It appears the miniUART of the Pi 3B+ maxes out at about 1Mbs, downhill, on ice, with a stiff tailwind. Now the UART on the FONA is capable of much faster; over 3Mbps.
I was about to look into dedicating one of my USB ports to the FONA when I saw on the board the two holes near the antenna labeled "SDA" and "SCL". They seemed familiar (I know nothing of I2C except that it's probably faster than UART).

So I got to wondering if maybe I could connect my Pi to the FONA via i2c... but I can find no documentation for them anywhere, nor mention that anyone uses them.

Can anyone educate me on this?

Hiraghm
 
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Re: FONA Sim5320A SDA SCL pins?

by adafruit_support_mike on Fri Nov 08, 2019 4:00 am

The FONA 3G's I2C port is mostly for connections to peripherals, with the SIM5320 as the master device. The commands AT+CRIIC and AT+CWIIC tell the FONA to do I2C read snad writes.

It's technically possible to make the SIM5320 act as an I2C slave device, but we don't have any documentation about how to do it. That's probably something you'd have to do in the module's firmware.

The issue is kind of moot if you're looking for speed though: the I2C bus maxes out at 400kHz.

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Re: FONA Sim5320A SDA SCL pins?

by Hiraghm on Fri Nov 08, 2019 1:23 pm

What could you connect to the FONA's i2c, with it as master? an i2c audio amp? accelerometer/gyro?

Hiraghm
 
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Re: FONA Sim5320A SDA SCL pins?

by adafruit_support_mike on Sat Nov 09, 2019 1:22 am

Those, a Seesaw IO expander:

https://www.adafruit.com/product/3657

any number of sensors, and so on. Think of remote data monitoring systems where you want to be able to pull data on demand.

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Please be positive and constructive with your questions and comments.