Monarco-HAT-Hardware-Reference-Manual

Monarco HAT Hardware Reference Manual 20190728-1

Digital Inputs (DIN) 3.2.3.

Description and Electrical Design

Monarco HAT has 4 digital inputs isolated by a high speed optocouplers. Digital inputs have a

common ground (minus pole) so they are sink-type inputs.

Voltage levels are designed to be compatible with both 24 V industrial sensors and 5 V standard logic,

with tolerance to negative voltage up to 30 volts.

 Logic low voltage: −30 V to 1.8 V

 Logic high voltage: 3.5 V to 30 V

 Input current: 0.8 mA (at 3.5 V) to 9.0 mA (at 30 V)

Here we show a few examples of devices which can be connected to Monarco’s digital inputs:

 dry contacts (switches, push buttons, relays),

 proximity sensors with 10 V to 30 V power supply and PNP (source, switching to plus) or NPN

(sink, switching to zero) output,

 standard PLC source-type 24 V outputs,

 standard 5 V logic outputs – e.g. 5 V encoders, logic gates,

 open drain outputs with pull-up which is able to supply at least 3.5 V / 0.8 mA.

Image 3.2: Digital inputs internal implementation.

Technology Functions Overview

Thanks to an ARM microcontroller embedded in Monarco HAT, digital inputs (and also outputs) can

be used also with advanced technology functions, which are not possible with Raspberry Pi

integrated GPIOs, such as:

 pulse counter, with optional direction signal,

 quadrature (A/B) encoder counter,

 * measurement of frequency / period / pulse length..