albpower2seq4sid Posted March 5, 2012 Report Posted March 5, 2012 (edited) Hi, I tried this link, http://www.ucapps.de/mbhp/mbhp_core_lpc17_midi3_extension.pdf But I couln't open it 'cause a I need to connect more devices, I tought to use one more MIDI in/OUT ( #3 ) and two or three IIC modules I have my third SEQ_V4 working but i need more Midi IN/OUTs Sorry, I saw this: http://midibox.org/forums/uploads/tn_gallery_9659_127_3197.png Edited March 5, 2012 by albpower2seq4sid
TK. Posted March 5, 2012 Report Posted March 5, 2012 http://midibox.org/forums/uploads/tn_gallery_9659_127_3197.png This is the wrong schematic, it fixes a problem with a problematic MIDI device, but it isn't standard! Here the correct link: http://www.ucapps.de/mbhp/mbhp_core_lpc17_midi3_midi4_extension.pdf (I fixed the webpage and added the same link to the MBHP_CORE_LPC17 page now) Best Regards, Thorsten.
ilmenator Posted March 5, 2012 Report Posted March 5, 2012 There seems to be a small copy/paste error in the PDF: both additional MIDI ports are numbered #3, whereas I think one of those should be #4? Which one?
albpower2seq4sid Posted March 5, 2012 Author Report Posted March 5, 2012 Here the correct link: http://www.ucapps.de/mbhp/mbhp_core_lpc17_midi3_midi4_extension.pdf Ok, I opened that file, only one doubt more: is it 5 Volts or 3.3 Volts in both MIDI OUT'S ( #3 and #4 ) because on the Core LPC17 Schematic on both MIDI OUT, #1 and #2, there are 3.3 Volts ( after the 220 ohms resistors ) I had used both #1 and #2 MIDI OUT ( 3.3 VOlts ) and they are working well Thanks for your reply Best Regards
TK. Posted March 5, 2012 Report Posted March 5, 2012 Thanks again - the third error: wrong link, wrong enumeration, wrong supply voltage - ok, I created the schematic at new year's eve and was in hurry... ;-) The supply voltage is 3.3V since the output pins of the LPC17 UARTs don't support open drain mode which would allow to pull the voltage to 5V. Note: using 3.3V for the 1k pull-up at the output of the optocoupler shouldn't cause an issue. I changed it this way to avoid one additional cable to a +5V pin. Best Regards, Thorsten.
albpower2seq4sid Posted March 6, 2012 Author Report Posted March 6, 2012 Thanks again - the third error: wrong link, wrong enumeration, wrong supply voltage - ok, I created the schematic at new year's eve and was in hurry... ;-) The supply voltage is 3.3V since the output pins of the LPC17 UARTs don't support open drain mode which would allow to pull the voltage to 5V. Note: using 3.3V for the 1k pull-up at the output of the optocoupler shouldn't cause an issue. I changed it this way to avoid one additional cable to a +5V pin. Best Regards, Thorsten. Hi Thorsten, I test the MIDI IN/OUT with 3.3 V and they work perfectly. No problem with 3.3 V on optocoupler. MIDI OUT #3 with 3.3V works well. Thanks Thorsten for your support Best Regards, Alberto
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