Re: How to I2C in RPi3B+ (also gpioiic) ?

[email protected] ("Dr. Nicola Mingotti") writes:

>1. Is anybody able to get some form of I2C to work ?

yes.

http://cdn.netbsd.org/pub/NetBSD/misc/mlelstv/antipasti2.jpg

shows an RPI0W driving two I2C devices, a CO2 sensor from Sensirion
and an OLED display.

http://cdn.netbsd.org/pub/NetBSD/misc/mlelstv/scd30.tgz

has the C source of the program running.

>2. Does it exist a command similar to i2cget in NetBSD to query
>    directly a device via shell ? Otherwise, is there a code
>    snipped around I can start from to get the same thing in C ?

There is no such command in base.

man 4 iic shows the device ioctls that are used to send or receive
data.

The standard DTB has 3 I2C controllers enabled, but only one
(i2c@7e804000) is supposed to be used and configured on GPIO.

When all 3 I2C controllers are enabled that "good" controller
should be /dev/iic2.


>3. using gpioiic the widget was recognized and it seems
>    the device dsrtc0 was created (I guess a driver was found) but
>.. Where is it ? I don't see it in /dev/
>.. How do I use that device dsrtc0 ?

That device has no interface to userland, the driver attaches to
the todr(9) routines to provide a time-of-day clock to the kernel.
You can read it with gettimeofday() or set it with settimeofday().