Sensor module

Sensor module includes Sensor board with on-board sensors, low-pass filter and external sensors.

Sensor module features

  • Electret microphone
  • Light intensity sensor (photoresistor) VT935G (resistance 18,5 kΩ on 10 lux) datasheet
  • Temperature sensor (thermistor NTC) (resistance 10 kΩ on 25 °C) datasheet
  • Potentiometer 10 kΩ
  • Ultrasonic distance measure sensor Devantech SRF05 with cable (measuring distance 1-400 cm) datasheet
  • Infrared distance sensor Sharp GP2Y0A21YK0F (measuring distance 10-80 cm) datasheet

Electrical connections

On-board sensors are connected as follows:

on-board notationexternal notationon-board sensormicrocontroller port
LDRAD1Light intensity sensorPF1
NTCAD2Temperature sensorPF2


Every sensor on the board is connected through the multiplexer, enabling to select between on-board sensor or external sensor which can be connected to the same port through the connectors. By default all on-board sensors are connected to the analogous inputs of the microcontroller (ADC0-ADC3). Multiplexer is controlled with the port PG0.

Schematics of multiplexer
Schematics of sensor connections

Low-pass filter

Low-pass filter can be composed between external analogous inputs 0-3 (PF0-PF3). Resistor and capacitor will be connected to the socket for building up the low-pass filter. By default a low-pass filter is not composed only 1 Ohm resistors are included for all channels.

Schematics of external sensor connections and low-pass filter

Digital I/O connector

In addition to sensors and analog inputs, there is a connector for digital I/O. Digital I/O pins are directly connected to pins PE2-PE5 of the controller. Also digital serial interface connector is in use (74HCT165D), which is convenient for connecting similar digital sensors. Digital serial interface is connected as following: clock input - PC7, asynchronous parallel load input (active LOW) - PA6, serial output from the last stage - PA7.

The digital input/output connectors
en/hardware/homelab/sensor/v52.txt · Last modified: 2020/07/20 14:26 by
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