midi in and lcd not working

[Guest kejace]

Hello.. I've still got the same problem with midi-in and MIOS (http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=troubleshooting;action=display;num=1059565097) which I haven't found a solution to.

So I switched the crystal and plugged in the 16F877 and tested two DIN/DOUT modules and they both work, however I've tried with two different LCDs (16x2, different pinning) and they both just light up and show the first line full of black boxes and nothing on the second line. (This is what I get when MIOS bootloader is running too.)

I suspect there is some strange voltage around somewhere (suggested by TK in the previous post) but

what I can't understand is why the PICs and midi-out is working?! Where should I look?

I should point out that the DIN/DOUT modules both work independent of whether the LCD is connected or not, the problem is that it doesn't show anything on the display but the black line on the DIN test.

Any suggestions?

[TK.]

Hi Kejace,

• check that your MIDI interface is working: loopback the MIDI Out of your PC to the MIDI In of your PC and send a SysEx dump by using the "Send/Receive SysEx" function of MIDI-Ox. The number of sent bytes must match with the number of received bytes. If it doesn't match, search for a new driver for your MIDI interface/sound card. If not available, you can possibly fix this problem by lowering the Low Level Output Buffer size (normaly set to 2048 ) and by increasing the output delay (normaly set to 0 ms) in the MIDI-Ox SysEx configuration menu
  
• check the polarity of your MIDI cable (the MBHP_CORE schematic http://www.ucapps.de/mbhp/mbhp_core.pdf) shows the rear view of the MIDI socket)
  
• check the polarity of the protection diode D1
  
• check the supply voltage of the optocoupler IC2 between pin #5 and #8: 5V
  
• check the output voltage between pin #5 and #6 of IC2: 5V (caused by the 1.2k pull-up resistor R6)
  
• try the MIDI-In tests: http://www.midibox.org/cgi-bin/yabb/YaBB.cgi?board=troubleshooting;action=display;num=1055726526
  

Best Regards, Thorsten.

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