[sdiy] Microchip PIC 5 x 4 matrix

[Rick Jansen]

If you can use an I2C bus the PCF8574 is nice for this too. 2 pins for serial communication, plus an interrupt, if you want to use that. With 3 8574's you can read 24 switches. Each switch just connects to GND, no matrix necessary. 

rick

> On 07 Oct 2015, at 15:52, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
> 
> I'm about to build a MIDI foot controller
> using around 20 normally open footswitches
> with there respective state LEDs.
> I have a bunch of PIC16F88 micros and want
> to use one for this project using as less pins as possible.
> (9 pins for the matrix)
> I figured out a way to read and feed all switches
> and LEDs this way:
> 
> http://www.arcenson.com/public/PIC16F88_5x4_matrix.JPG
> 
> All the switches and LEDs will be processed one after each other
> in an endless loop..
> RB5 will send the MIDI data.
> 
> Does anybody see something I forgot in that drawing ?
> I'm not home and will try it tonight.
> 
> Thanks. JP
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