4-20Ma Sensors; Watermark Sensors - Arduino AKX00034 Product Reference Manual

Arduino® Edge Control

3.5 4-20mA Sensors

Up to four 4-20mA sensors can be connected to J4. A reference voltage of 19V is generated by the MP1542 step-up
converter to power the current loop. The sensor value is read via a 220 ohm resistor. Each input is connected to an
analog multiplexer (MC14067) that channels the signal to a single ADC port. The main processor controls the input
selection via a TCA6424 port expander over I2C.
Low power sensors schematic

3.6 Watermark Sensors

Up to sixteen hydrostatic watermark sensors can be connected to J8. Pins J8-17 and J8-18 are the common sensor
pins for all the sensors, controlled directly by the microcontroller. Inputs and the common sensor pins are
protected by a 19V Zener diode.
Each input is connected to an analog multiplexer (MC14067) that channels the signal to a single ADC port. The main
processor controls the input selection via a TCA6424 port expander over I2C. The board supports 2 precision
modes.
Watermark input
12 / 25 Arduino® Edge Control Modified: 17/12/2021