PIC16F628 4 RGB LED PWM Controller using pic microcontroller




I am a big fan of LEDs.  Bright, colorful, flashing LEDs.  So, given my affinity for LEDs, I decided to work on a controller that me and a few of my friends could use as an art project/passive information display.  I have posted videos from the first prototypes (here and here), but it has been tough to dedicate time to further development given my research, so I thought I would post the information so that anyone can take the design and modify it to their liking!

PIC16F628 4 RGB LED PWM ControllerSome insipration came from the BlinkM “smart LED” and the ShiftBrite RGB LED Module, but I was interested in using RS232 serial control.  Therefore, I chose one of my favorite simple-to-use microcontrollers, the PIC16F628.  The advantages include the built-in 4MHz oscillator, hardware USART, and ease of reprogramming.  A couple of features I had in mind during the design:

  1. Multiple intensities for each color (using PWM)
  2. Multiple individually controllable RGB LEDs
  3. High-speed update rate
  4. Daisy-chainable and addressable
  5. Simple serial control

Schematic
Here
is the full schematic for the driver. I chose to use a PIC16F628 as the microcontroller because it is cheap, has a internal oscillator (4 MHz) and an internal USART. NOTE: There is an error in this schematic and a pull-up resistor on RA5 (pin 4 in the schematic) is necessary.  See the bottom of the post for an updated schematic and board.

PIC16F628 4 RGB LED PWM ControllerBoard
I decided I would try getting a PCB printed for the first time, so I got boards created at BatchPCB.com for $5 each.  The total for 4 boards shipped was $32.36 (4 x $5 for the boards and $12.36 for shipping and handling).  They took a long time to arrive, but the quality was well worth the wait.  NOTE: There is an error on the first revision of the board and a pull-up resistor on RA5 (pin 4 in the schematic above) is necessary.  You can see how I compensated for the mistake in the second picture below (look on the back of the upper-left board).  This will be corrected in future revisions.  See the bottom of the post for an updated schematic and board.

 

For more detail: PIC16F628 4 RGB LED PWM Controller




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