Multi colour LED driver
Each of the PIC’s outputs can only drive one LED (I.e. One PIC can directly drive one tri-colour device). However, it is possible the use a simple transistor buffer to increase the number and brightness of the LEDs used.
There are slightly different circuits for common anode or common cathode tri-colour LEDs. The common cathode uses an NPN transistor I’ve used a 2N3904 although many low power low frequency NPN transistors would work. Similarly, the Common anode circuit uses a 2N3906 , many low power low frequency PNP transistors would work equally well. Each of these circuits will comfortably drive four tri-colour devices.
There are slightly different circuits for common anode or common cathode tri-
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Downloads (free for personal use only - copyright W.K.Todd 2005 all rights reserved)
VB control application (LED Driver.exe - installer 1.2MB) Download and install.
VB source code (leddriverVB.zip - 18kB) requires VB5 or 6
PIC 12F675 or 12F629 object code (LEDS.HEX 3kB) to download, right click and select Save Target As...
Links
Component Shop - eBay.uk based supplier. Very cheap tri-colour LEDs
VB control application (LED Driver.exe -
VB source code (leddriverVB.zip -
PIC 12F675 or 12F629 object code (LEDS.HEX 3kB) to download, right click and select Save Target As...
Links
Component Shop -