I first noticed this with my custom kernel and then confirmed it on a Raspberry Pi 4 running 64-bit Raspberry Pi OS. All data below is from Raspberry Pi OS.
Kernel info:
I2C settings in config.txt:Actual I2C frequency appears to be about 40 kHz:
![Image]()
http://tech.munts.com/images/TEK0000.JPG
Then I tried changing the frequency to 400 kHz:Now the actual frequency is about 181 kHz:
![Image]()
http://tech.munts.com/images/TEK0001.JPG
Kernel info:
Code:
Linux zoar.munts.net 6.1.0-rpi8-rpi-v8 #1 SMP PREEMPT Debian 1:6.1.73-1+rpt1 (2024-01-25) aarch64 GNU/LinuxCode:
pmunts@zoar:~$ grep i2c /boot/firmware/config.txtdtparam=i2c_arm=on,i2c_arm_baudrate=100000#dtparam=i2c_vc=on,i2c_vc_baudrate=100000
http://tech.munts.com/images/TEK0000.JPGThen I tried changing the frequency to 400 kHz:
Code:
pmunts@zoar:~$ grep i2c /boot/firmware/config.txtdtparam=i2c_arm=on,i2c_arm_baudrate=400000#dtparam=i2c_vc=on,i2c_vc_baudrate=100000
http://tech.munts.com/images/TEK0001.JPGStatistics: Posted by pmunts — Wed Feb 28, 2024 2:19 am