Analog Input - ADC

Board	External signals	Precision	Maximum input voltage
RZ/G3E SOM	8 signals divided into 1 channel with 8 inputs	12 bit	1.8V

warning

Note that input voltages above maximum input voltate will damage the CPU.

The analog pins are available on JP21 on the back side of the SOM Carrier Board:

Pin 1 of JP21 is marked with a small triangle (left in the picture).

To safely test the ADC pins with the commands below, use a male-male jumper cable and connect the pin that you want to test with either pin 9 (for HIGH) or pin 10 (for LOW).

U-Boot

Not currently available.

Linux

Each ADC channel will be represented by a iio:device node in the file system.

ls /sys/bus/iio/devices/

iio:device0

ls /sys/bus/iio/devices/iio\:device0/

in_voltage0_get_value  in_voltage3_get_value  in_voltage6_get_value  power
in_voltage0_raw        in_voltage3_raw        in_voltage6_raw        subsystem
in_voltage1_get_value  in_voltage4_get_value  in_voltage7_get_value  uevent
in_voltage1_raw        in_voltage4_raw        in_voltage7_raw        waiting_for_supplier
in_voltage2_get_value  in_voltage5_get_value  name
in_voltage2_raw        in_voltage5_raw        of_node

In this case (RZ/G3E) the 8 signals are all in one channel (iio:device0) with 8 inputs (in_voltage0_raw, in_voltage1_raw, ... in_voltage7_raw).

To read the raw value (range is 0 - 4095 for 12 bit precision).

cat /sys/bus/iio/devices/iio\:device0/in_voltage2_raw

302

As the raw value is in range 0 - 4095 and the maximum input voltage is 1.8V you can scale the read value into mV like this:

actual_value = (raw_value * 1800) / 4095

Raw	Actual Value
0	0 mV
302	132 mV
4095	1800 mV