Re: PCF8574 I2C configuration for 14.0-CURRENT on a RPi2B
- In reply to: Brian Scott : "Re: PCF8574 I2C configuration for 14.0-CURRENT on a RPi2B"
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Date: Mon, 07 Mar 2022 16:10:12 UTC
Brian Scott wrote: > > I think I'm like most people here, trying to guess what you are wanting > to achieve. Pins 2 and 3 are already avalable as iic1 provided you include: > > dtparam=i2c_arm > > in your config.txt file. There's a little more magic needed on the rpi4 > but that doesn't effect you. > > Pin 3 (GPIO 2) is SDA and Pin 5 (GPIO 3) is SCL. This 'seems' to be the > opposite of what you are doing in your dts snippet so I could be wrong, > but I would have thought these functions would be hardwired in the SOC. > > As for your specific device, PCF8574; I don't have any direct experience > but it looks like a standard IIC device that should work OK. I see there > is a FreeBSD kernel module to support it but it is quite recent so > probably only in CURRENT. As I said, I don't have experience with that > particular device. > > Hope this helps, It did indeed. Problem solved. Mucho gracias! ------------------------------------------------------------------------ root@generic:~ # cat /boot/msdos/config.txt init_uart_clock=3000000 enable_uart=1 kernel=u-boot.bin kernel7=u-boot.bin dtoverlay=mmc dtparam=i2c_arm root@generic:~ # ls /dev | grep iic iic0 root@generic:~ # i2c -sv dev: /dev/iic0, addr: 0x0, r/w: r, offset: 0x00, width: 8, count: 1 Hardware may not support START/STOP scanning; trying less-reliable read method. Scanning I2C devices on /dev/iic0: 27 ------------------------------------------------------------------------ Danke, -- Don, KB7RPU, https://www.qsl.net/kb7rpu There was a young lady named Bright Whose speed was far faster than light; She set out one day In a relative way And returned on the previous night.