PIC-WEB Multiple Switches

Started by The Professor, January 07, 2020, 08:47:12 AM

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The Professor

Hi All,

I hope someone could help me please?

I am very new to this product, in fact I am so new as to be waiting for my PIC-WEB to arrive. Unfortunately the project I am going to use it for does not give me much time for development.

My question is hopefully quite simple, and is regarding the connection of switches to the board.

A bit of background:-
I am going to use the board as the foundation of a remote control. The remote control will consist of the PIC-WEB board, a MOD-LCD4.3" as a display, and 17 switches for control.

My plan is to create a matrix of switches, I guess that I am using the EXT connector, but am struggling as to identify the correct pins to connect my switch matrix to.

Can someone offer a little guidance please?

Thanking you in anticipation


What is this "switch matrix"? Is it a ready product? What interface you need for it?
Technical support and documentation manager at Olimex

The Professor

thank you for relying....

the switch matric is a simple grid pattern to allow me to connect multiple switches to the minimum number of pins.

having spent some time looking at the I/o pins on EXT, I am assuming (dangerous I know) that the EXT pins can be set as input or output, with specific pin related functions as needed.

I have worked along the lines of pins 1,2,3,4,5 being used as my column pins and pins 6,7,8,9,10 being the rows.

I am going to get a PCB made to hold the connectors for each of the switches being used

Am I right in this thought process?


The simple grid requires simple digital IOs right? What level TTL or CMOS?

You should use either the EXT header or the UEXT header. Whether a pin is input-output, or input only, or output has to be double checked using the schematic and the PIC18F97J60 datasheet (in the datasheet you see column "Pin Type" which says if a pin can be I or O or I/O or if it a power pin, etc). You would also need to check the level of the pin in the next column called "Buffer Type".

The schematic is here: https://www.olimex.com/Products/PIC/Development/PIC-WEB/resources/PIC-WEB-Rev_C-schematic.pdf

The datasheet here: http://ww1.microchip.com/downloads/en/devicedoc/39762f.pdf

So for example, you wonder whether pin EXT-12 can be used - you check the schematic and see that it is connected to processor port RB1. You open the datasheet and search for RB1 and it sends you to page 34 where you see that it is a digital I/O at TTL level.
Technical support and documentation manager at Olimex

The Professor

Thank you Lubolimex.

The levels I am looking for are either CMOS or TTL, they are connected only to the PIC-Web.