Robert Ross
Engineering Projects - Persistence of Vision Sign Writer
"LEDs + motion = message in the air"
Robert Ross |
||
Engineering Projects - Persistence of Vision Sign Writer"LEDs + motion = message in the air"
|
||
|
This project was my first completed project which I took the primary role as supervisor. Duc, one of my third year students did a superb job, completing the project from start to finish in less than a month.
The concept here was fairly simple: Affix a row of LEDs on a rotating circuit board. As the board rotates through the arc the LEDs turn on and off in sequence writing out the message which was programmed in.
A IR photodiode/LED pair was used to determine the rotational rate and the current position. A MSP430 microcontroller was used to control the LEDs and with its 2.4GHz wireless interface will allow a future upgrade to dynamically write messages from a computer.
The software implementation involved a IR phototransistor (via a comparator) triggering an external interrupt. When the interrupt is called the current timer value is stored and the timer count in reset back to zero - this provides a count of the rotational rate and allows the microprocessor to determine how long the LEDs need to be turned on - implemented via SW delays.
|
|
|
||
|
POV photos |
||
 |
 |
 |
| The first message displayed - just in time for the La Trobe open day | At night with the lights out the display really writes up a clear message | A still shot of the POV signwriter |
|
|