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PIC Lightbarrier

A Light Barrier with a PIC18F25J11 powered over Micro-USB.

Principle

The device counts the people who walk through the lightbarrier and with the help of the second lightbarrier also detects in which direction they went.

Optional Features:

  • A night-mode (1 person in the room also turns off the ouput/relay), display the mode on the LCD.
  • Show person count on the LCD

Specs

Overview

External

  • Connector for IR-Receiver, IR-LEDs, Relay (or something else with 5V input) and 3 additional free I/Os
  • Connector for display (HD44780 compatible, contrast regulaton possible)

On-board

  • 1 microcontroller (PIC18F25J11)
  • 2 IR-receiver (TSSOP3438) and IR-LEDs with associated drivers (PNP-MOSFET)
  • 1 solid-state-relay (230V AC)
  • 1 volatge regulator (5V to 3.3V)
  • Micro-USB connector

Microcontroller

The internal oscillator is configured with a freqency of 8 MHz (maximum without PLL). The reasons for using the internal oscilltor over an external are saving precious PCB space, saving money and the whole device isn't laid-out for high-speed applications.

TSSOP3438

The TSSOP3438 detects IR light with 38 kHz frequency.

Relay (and gneral output)

The output is high as soon as someone is in the room. Additionally there is also an onboard solid-state-relay to toggle up to 230 V AC.