PicPOV – Persistence of Vision with a PIC18F1220


PicPOV is a project based on “persistence of vision”.  A PIC microcontroller blinks 8 LEDs on and off so that when waved through the air, a message appears to float in front of the viewer.

Persistence of Vision

Design and Implementation

The design goals were:

  • be simple to use;
  • capable of storing multiple messages;
  • simple to change between messages;
  • simple to load new messages.

A small microcontroller like the PIC18F1220 does this job just fine! It has only 18 pins, an internal oscillator, eeprom and a serial port.

  • The internal oscillator removes the need for a crystal;
  • Multiple messages are stored inside the eeprom;
  • One button changes to the next message (8 in total);
  • New messages can be loaded through the serial port using any terminal program.

The serial port connection is usually implemented using a MAX232 or similar IC but to reduce the costs even more, a simple 2 transistor solution is used.


Schematic Persistence of Vision

The circuit is divided in three areas:

  • Microcontroller, LEDs and button on the left side are the basic POV circuit;
  • Two transistors and 4 resistors on the bottom right implement a level shifter to to interface with the serial port;
  • and finally at the top right a power supply.

For more detail: PicPOV – Persistence of Vision with a PIC18F1220

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