Avx: Analog Voltage Inputs; Aix: Analog Current Inputs - Sferalabs Iono Pi Max Series User Manual

The analog section of Iono Pi Max is enabled by default, but can be disabled, turning off
the dedicated isolated DC-DC converter, the ADC and the analog front-end stage.
The sysfs analog enable file is analog_in/enabled (I2C control register 69).
The firmware also controls a high-speed filter for the analog voltage and current inputs.
The control file is analog_in/hsf (I2C control register 69). This is disabled by default.
Enabling the high-speed filter results in a faster sampling rate, but also increased noise
over measured values.
The data refresh period for voltage and current inputs is 900ms, and approximately 270ms
with the high-speed filter enabled. Note that the AD4112 ADC can achieve much higher
SPS (samples per second) rates than the data refresh period supported by the Iono Pi
Max firmware, and can be implemented with custom firmware.

AVx: Analog voltage inputs

Iono Pi Max has 4 single-ended analog voltage inputs that can be individually configured in
unipolar mode, with a 0-20V range, or in bipolar mode, with a -10V to +10V range.
The ADC is factory calibrated to achieve a ±0.06% accuracy (at 25°C). The voltage inputs
front-end impedance is ≥1 MOhm.
NOTICE
The voltage inputs are protected from electrostatic discharge with transient voltage
suppression diodes. The AD4112 voltage inputs have a ±50V absolute maximum rating.
Connecting a voltage source outside the measuring range could damage the ADC or other
electronic components.
You can set the unipolar or bipolar configuration with the analog_in/av<n>_mode (I2C
control register 69). Measured values in mV/100 are available in the analog_in/av<n> files
(I2C control registers 71-74, 24 bits resolution).

AIx: Analog current inputs

Iono Pi Max has 4 analog current inputs that can be individually configured in unipolar
mode, with a 0-20mA range, or in bipolar mode, with a -10mA to +10mA range.
The ADC is factory calibrated to achieve a ±0.08% accuracy (at 25°C). The current inputs
front-end impedance is 240 Ohm.
NOTICE
The current inputs are protected from electrostatic discharge with transient voltage
suppression diodes. Resettable fuses on each input line also protect from over-current
events. Even with these protections in place, input currents exceeding 50mA could
damage the ADC or other electronic components.
You can set the unipolar or bipolar configuration with the analog_in/ai<n>_mode (I2C
control register 69). Measured values in µA are available in the analog_in/ai<n> files (I2C
control registers 75-78, 24 bits resolution, signed two's complement).
37 Iono Pi Max User Guide