S0ImpulseCounter/Hardware/Schematics

DualS0ImpCounter - Hardware

Arduino based hardware for capturing impulses from S0 impulse meters.

Hardware

• based on Arduino Pro Mini (or clone, with ATmega 328p MCU)
• power supply using a 12VDC wall plug
• big buffer capacitor only for the MCU itself, right before it´s diode decoupled 5VDC regulator,
• resistor network from 12VDC supply to ADC input to detect power loss early enough
• 2 S0 impulse inputs using optocouplers, active LOW (compatible with S0 outputs, which are usually open collector outputs)
• connection to host over RS232, so NOT USING USB POWER SUPPLY
• RS232 connection without DTS signal, so that the MCU cannot be surprise-reset by the host on (re-)connect
• reset circuit (connection from a GPIO out to /RES input)

Schematic

Board Layout