I2C/IIC working on RPI4 8GB?

[Mark Murray]

On 26 Apr 2021, at 15:11, Emmanuel Vadot <manu at bidouilliste.com> wrote:
> 
> On Sun, 25 Apr 2021 13:32:00 +0100
> Mark Murray <markm at FreeBSD.org> wrote:
> 
>> Hi All,
>> 
>> Does anyone here have IIC/I2C working on a CURRENT (I'm running latest) FreeBSD?
>> 
>> I've never seen it work; Last time I had working IIC was on an RPI3.
>> 
>> There is a /dev/iic0, and I have a known working RTC on it, but the scan just times out:
>> 
>> [root at grasshopper ~]# i2c -s
>> Hardware may not support START/STOP scanning; trying less-reliable read method.
>> <TIMEOUT>
>> Scanning I2C devices on /dev/iic0: <none found>
>> 
>> 
>> I suspect something not-quite-right in DTS land, but I lack the knowledge to investigate. I've done some random stumbling around in the dark with overlays and the like, but I've either seen the above error, or a total lack of /dev/iic0.
>> 
>> Thanks!
>> 
>> M
>> --
>> Mark R V Murray
>> 
> 
> I2C is disabled by default.
> You need to copy i2c0.dtbo (or i2c1<X> I don't know which one maps to
> the pins you want to use) in the ESP partition and add "i2c<X>" to the
> dtoverlay line in config.txt

I want to use the i2c on the "regular" pins, GPIO2 and GPIO3, AKA physical pins 3 and 5.

I looked at all the i2c[0-6].dtbo overlays in /usr/ports/sysutils/rpi-firmware. Only 1 had "pins = <2, 3>", so I used that one. I presume the 2,3 refers to GPIO pin numbers, not physical pin numbers?

Same result as before - long timeout, no I2C.

M
--
Mark R V Murray

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