MIDI #3 IN/OUT

MIDIbox SEQ
1

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:

2

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.

3

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?

4

Thank you! Fixed

Best Regards, Thorsten.

5

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

6

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… :wink:

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.

7

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… :wink:

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