intellijel Posted November 15, 2006 Report Share Posted November 15, 2006 To TK (and others following the development of the SEQV3)On the monome page they had some documentation about using diodes as part of the button array to avoid the problem of "ghosting""...button system uses surface mount diodes to prevent ghosting. this method lets us discretely detect press and release of all keys simultaneously. diodes are placed by hand after solder-pasting (more information on this in the next section), then baked in the toaster oven."http://www.dribin.org/dave/keyboard/html/ghosting.htmlAlso, in your sticky you mentioned there were some new button/led options?cheers, intellijel Quote Link to comment Share on other sites More sharing options...
TK. Posted November 15, 2006 Report Share Posted November 15, 2006 Hi,yes, of course, diodes are required whenever buttons are connected together to a matrix. You can find them in the schematic as well:http://www.ucapps.de/mbhp/button_duoled_matrix.pdfjust use any "general purpose" diode, e.g. 1N4148The direction is important!The additional button/LED options are documented in the CHANGELOG.txt: o there are now 4 additional buttons and LEDs for selecting the track group (G1=track 1-4, G2=track 5-8, G3=track 9-12, G4=track 13-16) and 3 additional buttons and LEDs for the trigger layers A, B, C and 1 additional button and two LEDs to switch between step 1-16/17-32 The pin assignments are made in mios_tables.inc (or within the setup_*.asm file) PLEASE NOTE: these buttons/LEDs are optional and could be added for a more comfortable usage in case that somebody creates a new frontpanel. The same functions are also accessible in following ways for people who already built a MBSEQ (e.g. V2) - Selecting group: can by cycled with F4, track can be directly selected by holding Mute button and pressing the appr. GP button 1-16 The selected group is visible in most menu pages - Selecting trigger layer: can be cycled with F3, the selected layer is only visible within the edit page - Switch between Step 1-16/17-32: can also be done with F2, or by doubleclicking a track selection button o added optional LEDs for Play/Stop/Pause[/code]Best Regards, Thorsten./EDIT: step 1-16/17-32 button/LEDs now available Quote Link to comment Share on other sites More sharing options...
fluke Posted November 15, 2006 Report Share Posted November 15, 2006 A slightly off topic question, but shouldn't you have a transistor in the DEFAULT_SRM_DOUT_CATHODES_R D0-D3? You've got it sinking current from 16 LEDs per pin and i thought a 74HC595 could only sink 20mA per pin. My calculations say that if all the LEDs are on, you'll need to sink around 250mA per pin. Quote Link to comment Share on other sites More sharing options...
TK. Posted November 16, 2006 Report Share Posted November 16, 2006 You are right when saying, that this circuit is not ideal for all type of LEDs, and if the matrix should be used for other purposes than for the sequencer. Here my hope is, that the community improves the circuit and especially tests and writes documentation in the Wiki.For myself the situation is a little bit relaxed. The LEDs don't consume that much power, and in general there are never more than 8 green + 1 red LED driven by a 74HC595 at one moment. Yes, the output driver of a single pin is overdriven, you can notice this by measuring the voltage - it's not 0 anymore, but ca. 1V (out of spec). Thats the reason, why there are seperate "cathode" pins for the buttons. These are just duplicates of the LED outputs which drive proper 0V/5V.Just to highlight it again: please improve this circuit, test it and publish the documentation! It will save effort at my side. I don't really want to take care about everything...Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
fluke Posted November 16, 2006 Report Share Posted November 16, 2006 I do intend on building one, so i'll wiki my design as soon as i do. Now i just have to figure out a user interface design for a Midibox FM involving 48 led/buttons, a PalmPilot and a few encoders... Quote Link to comment Share on other sites More sharing options...
stryd_one Posted November 17, 2006 Report Share Posted November 17, 2006 In case you're wondering, yes, fluke has gone crazy. ;) Quote Link to comment Share on other sites More sharing options...
fluke Posted November 18, 2006 Report Share Posted November 18, 2006 I think so too. Quote Link to comment Share on other sites More sharing options...
napierzaza Posted February 1, 2007 Report Share Posted February 1, 2007 Has anyone improved this design yet or have any tips? Quote Link to comment Share on other sites More sharing options...
napierzaza Posted February 1, 2007 Report Share Posted February 1, 2007 Okay, I think I have good orderlist for this module. Is the following enough to make one? (bare bones).[tt] 74HC595 6 511-M74HC595 74HC165 2 511-M74HC165 IC-Sockets for ICs 8 571-3902614 Dual LEDs 64 Momentary Push-Buttons 64 Diode 1N4148 " 64 78-1N4148 Resistor 220 Ohm " 8 291-220K-RC Resistor 150 Ohm " 8 291-150K-RC[/tt] Quote Link to comment Share on other sites More sharing options...
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