This driver is build and tested on a raspberry pi 3 using version 5.10.14-v7+ of the linux kernel. there is one helper script that simply recompiles the module then reloads it. to run it run ./reload_mod
to compile the helper script run gcc test_dac.c -lm -o test_dac, this will create an executable called test_dac this program writes to sin waves to the dac.
Though the DAC can be opened like a normal file you must do a few IOCTL operations before you can properly write to it.
- First you must enable the dac, this is done with:
ioctl(fd, DAC_IOEN) - Then you must set a frequency (the time between writes to the dac):
ioctl(fd, DAC_IOSF, 1000)to dwrite to the dac every millisecond, note there is some variance as it takes to to actually write each byte. - Finally, you must disable the dac when done:
ioctl(fd, DAC_IODE).
to get a better context, look in dac_test.c