khofesh / iot-in-c

Raspberry Pi 4 - IoT in C

Raspberry Pi IoT in C

BCM 2835

sudo apt install libbcm2835-dev

check where files are installed

dpkg -L libbcm2835-dev

Rasberry Pi General

clock speed

sudo vcgencmd measure_clock arm

this gives you the frequency that all of the cores are running at.

discover the current active governor

sudo cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

check the available

sudo cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

a set of governors control how the frequency is varied

The cpufreq governor "ondemand" sets the CPU frequency depending on the current system load. Load estimation is triggered by the scheduler through the update_util_data->func hook; when triggered, cpufreq checks the CPU-usage statistics over the last period and the governor sets the CPU accordingly.

the current clock rate according to Linux

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

the maximum and minimum frequencies

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

set fixed clock frequency

sudo sh -c "echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"

References

• https://www.airspayce.com/mikem/bcm2835/index.html