bbb adc - victronenergy/venus GitHub Wiki
The BBB has 7 ADC pins available for use with the Venus builds.
TI ADC Kernel documentation is here.
The BBB ADC's are 12-bit (0-4095) and have a input range of 0 - 1.8V
| Description | Port |
|---|---|
| Resistive tank sensor 1 | P9.33 AIN4 |
| Resistive tank sensor 2 | P9.35 AIN6 |
| Resistive tank sensor 3 | P9.37 AIN2 |
| Generic 0-10V sensor input | P9.39 AIN0 |
| Temp sensor 1 (LM335) | P9.36 AIN5 |
| Temp sensor 2 (LM335) | P9.38 AIN3 |
| P9.34 AGND |
Access the ADC pins through the sysfs iio interface
root@venus:~# ls /sys/bus/iio/devices/iio\:device0
buffer in_voltage2_raw in_voltage6_raw scan_elements
dev in_voltage3_raw name subsystem
in_voltage0_raw in_voltage4_raw of_node uevent
in_voltage1_raw in_voltage5_raw power
Here's a simple script to read the ADC values
#!/bin/sh
for i in 0 1 2 3 4 5 6; do
echo -n "ADC[${i}]: "
cat /sys/bus/iio/devices/iio\:device0/in_voltage${i}_raw
done
And here are a few tests using that script
All pins floating
root@venus:~# ./read_adc.sh
ADC[0]: 3969
ADC[1]: 3641
ADC[2]: 3985
ADC[3]: 1688
ADC[4]: 1956
ADC[5]: 3637
ADC[6]: 3516
All pins grounded
root@venus:~# ./read_adc.sh
ADC[0]: 1
ADC[1]: 1
ADC[2]: 9
ADC[3]: 8
ADC[4]: 11
ADC[5]: 7
ADC[6]: 11
All pins at 0.5V
root@venus:~# ./read_adc.sh
ADC[0]: 1112
ADC[1]: 1108
ADC[2]: 1110
ADC[3]: 1115
ADC[4]: 1109
ADC[5]: 1110
ADC[6]: 1106
All pins at 1.0V
root@venus:~# ./read_adc.sh
ADC[0]: 2428
ADC[1]: 2432
ADC[2]: 2433
ADC[3]: 2433
ADC[4]: 2430
ADC[5]: 2428
ADC[6]: 2438
All pins at 1.5V
root@venus:~# ./read_adc.sh
ADC[0]: 3505
ADC[1]: 3508
ADC[2]: 3507
ADC[3]: 3507
ADC[4]: 3503
ADC[5]: 3501
ADC[6]: 3499
ODD pins at 1.5V, EVEN pins grounded
ADC[0]: 0
ADC[1]: 3503
ADC[2]: 4
ADC[3]: 3504
ADC[4]: 18
ADC[5]: 3507
ADC[6]: 22