shed Posted June 20, 2004 Report Share Posted June 20, 2004 im thinking of trying to build a zx spectrum that i have lyeing around into a midi box. It has a membrane keypad, and i figure i may be able to conect it up to some DIN modules or something. But im not sure exactly, how this keypad works. So if anyone has any info on how possible this would be to do that would be excelent.Anhow this is a scan of the inside of the keypad, do i need to put together some sort of multiplexer to conect the inputs from the keys?sorry i guess i sound quite stupid, but thanks anyone who reads this.-ed Quote Link to comment Share on other sites More sharing options...
doc Posted June 20, 2004 Report Share Posted June 20, 2004 Hi,don't have further information on the zx...... but the pictures look like a 4 x 10 Matrix.If that is the case you can use it with a matrix.Look here:http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=mios;action=display;num=1084564072greetsDoc Quote Link to comment Share on other sites More sharing options...
shed Posted June 20, 2004 Author Report Share Posted June 20, 2004 duh thanks, i should have seen the example on the downloads page. Its a 5 x 8 matrix i think, but i recon it will be cool to play about with. I saw a alesis drum pad with similar buttons on it once, obviously it wont be the same without velocity but still cool to play about with. and for changing patterns and settings and stuff on synths and squencers it will be ideal, and cos it is absoultly tiny (about a 3rd of a PC keyboard) it can almost fit in my pocket Quote Link to comment Share on other sites More sharing options...
shed Posted June 21, 2004 Author Report Share Posted June 21, 2004 Cool anyway thanks for you help doc, i recon im about ready to get the bits i need to put this together. So il just go thrugh what i recon im going to put together and if anyone can see any problems with what i want to do a shout would be cool.So i need a core, and a DIN and DOUT module, and probibly a lcd for convinince. Then i conect up the matrix off the keypad to the dout and din module. and then join everything up to the core?On the concetion diagram off the mios downloads page, there is a diode after each switch on every colloumn, is it possible to have just one diode on the end of each rowthusinsted of like thiscos if not im going to have to hack the pad apart witch will be horrible.And witch way round is best to conect it? 8 Columns and 5 Rows or 5 Columns and 8 Rows.Well thanks if anyone has anything to say on this-ed Quote Link to comment Share on other sites More sharing options...
doc Posted June 21, 2004 Report Share Posted June 21, 2004 Unfortunately I think you'll need the diodes before every switch. Otherwise you connect a whole row every time you press one button (C0 e.g).Just paint the matrix with 2 lines and you'll know what I mean.I know that this is pretty difficult to realise with your keyboard. But maybe Thorsten know a better way to connect your keyboard.Doc Quote Link to comment Share on other sites More sharing options...
shed Posted June 22, 2004 Author Report Share Posted June 22, 2004 Humm yep, of course stupid me. Now i got out the spectrum circit board and there are 8 diodes conected to one end of the matrix, but they are the other way around from in Thorsten's diagram. So it could be that they did things the other way arround, now im not sure what this is conecting to, because i cant find out what the ic that they run into is.Anyhow, shouldnt this work, because although the coloumns are all conected to the same shift register the rows are all on sepreate ones.-ed Quote Link to comment Share on other sites More sharing options...
TK. Posted June 26, 2004 Report Share Posted June 26, 2004 I've noticed that the .syx file within the sm_example wasn't up-to-date, so please download the new package. It's now possible to use a scanmatrix with diodes in the other direction by swapping the column and row lines, and by setting SM_SWAP_CR to 1 in sm_simple.incBest Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
shed Posted June 27, 2004 Author Report Share Posted June 27, 2004 Nice one :) thanks tk Quote Link to comment Share on other sites More sharing options...
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