I have enabled the analog inputs on a Beaglebone Black by adding BB-ADC to optargs in uEnv.txt:
optargs=capemgr.disable_partno=BB-BONELT-HDMI capemgr.enable_partno=BB-SPIDEV0,BB-SPIDEV1,BB-UART1,BB-ADC The basic analog input works, if I do a: cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw it returns a value which is proportional to the applied voltage. However the value is not always up-to-date. If I change the input voltage, I can read the old input voltage several times before I can read the correct value. The strange part is that I am obviously not just reading a stored value, because the LSB can change on subsequent reads, until I finally read the correct value: jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 The applied voltage is now halved (from ~200mV to ~100mV). I wait for about 1 second between each read: jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 488 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 488 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 489 jsa@bb00:~$ cat /sys/bus/iio/devices/iio:device0/in_voltage3_raw 243 Finally I read the correct value. What is going on? Can I force an update (sample)? -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
