I2C/IIC working on RPI4 8GB?

[Hrant Dadivanyan]

Hi Mark,

Exactly the same here for 13.0-RELEASE. I use ds3231 on RPI-B and RPI3, 
but it never works on RPI4 8GB (periodically trying from August 2020 as 
far as I can remember). Not even when booting from the SD card pulled 
out from RPI3 and inserted into RPI4.
Found the following workaround though (config.txt):
#device_tree_overlay=i2c-rtc,ds3231
device_tree_overlay=i2c-rtc-gpio,ds3231,i2c_gpio_scl=2,i2c_gpio_sda=3
Please note pins REVERSE assignment in config.

# dmesg | egrep -i 'ds3231|rtc|i2c|iic|time-of-day'
iichb0: <BCM2708/2835 BSC controller> mem 0x7e804000-0x7e804fff irq 26 
on simplebus0
iicbus0: <OFW I2C bus> on iichb0
iic0: <I2C generic I/O> on iicbus0
Warning: no time-of-day clock registered, system time will not be set 
accurately
gpioiic0: <GPIO I2C> on ofwbus0
gpioiic0: SCL pin: gpiobus0:3, SDA pin: gpiobus0:2
iicbb0: <I2C bit-banging driver> on gpioiic0
iicbus1: <OFW I2C bus> on iicbb0 master-only
iic1: <I2C generic I/O> on iicbus1
ds32310: <Maxim DS3231 RTC> at addr 0xd0 on iicbus1
ds32310: registered as a time-of-day clock, resolution 1.000000s
#
Please note pins CORRECT assignment in the dmesg.

Thank you,
Hrant

On 4/25/21 4:32 PM, Mark Murray 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
> 

-- 
     Hrant Dadivanyan - hrant(at)dadivanyan.net
/* "Feci quod potui, faciant meliora potentes." */

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