SEQV4 / Aout NG issue [SOLVED]

MIDIbox SEQ
1

Finally installing some CV outs..

Maybe I overlooked something here but I am having a hell of a time getting everything to work together.

* STM32 Core

* SD card running Wilba’s HW config

* +5/+12/-12 Supply running fine

* Checked wiring from J19 10 times

* Checked components on NG board

I get good voltages on the NG board, nothing is hot but as soon as I turn on the core, all the outputs of the NG short to ground. Going to the CV config page none of the config voltages do anything..

Not a core issue since I swapped out cores with the same results

2

Does this help at all?:

http://discourse.midibox.org/t/topic/14382

3

First of all ensure that the AOUT_NG module is selected in the CV configuration page.

You haven’t mentioned this detail, therefore the reminder!

I would like to know how you’ve configured the J19 port? It needs 1k pull-ups and the J26 jumper should be set to 5V

Additionally: did you already try the “testaoutpin” command in MIOS Terminal?

Just enter this command, it will output some instructions how to test each individual connection between Core and MBHP_AOUT module! :slight_smile:

Best Regards, Thorsten.

4

First of all ensure that the AOUT_NG module is selected in the CV configuration page.

You haven’t mentioned this detail, therefore the reminder!

Yes, set to ng

I would like to know how you’ve configured the J19 port? It needs 1k pull-ups and the J26 jumper should be set to 5V

5V and 1k pull ups

Additionally: did you already try the “testaoutpin” command in MIOS Terminal?

Just enter this command, it will output some instructions how to test each individual connection between Core and MBHP_AOUT module! :slight_smile:

will do next

thanks

5

ok, CS and SI are right at 4V SC is at 5V. Is that normal?

forgot to mention something very important, when the module powers up, the outputs short to ground. This is coming from the analog side since it does the same thing when J1 is disconnected

I am also reading ~36K to gnd with nothing connected on all the outputs..

6

The voltages should be ok, and it’s normal that the outputs are at 0V after power-on.

Could you please continue reading here:

Greevous had similar issues, I gave him some hints which are also relevant for you.

He solved this by testing different cables (in general: than shorter than better), and it seems that also switching to 3.3V level (instead of 5V) helped, although I would recommend to test the 5V option first.

Sidenote: this information is only relevant for MBHP_CORE_STM32 users.

For MBHP_CORE_LPC17 I’m using a 74HCT541 based buffer which simplifies the level-shifting (makes it less troublesome)

Best Regards, Thorsten.

7

you rock man. It was the cable length. I left it extra long for debugging purposes, when I chopped it down it started talking to the DAQ chip. It did NOT work at 3.3V but sprang to life at 5. I can totally see why you are using the buffer with your external box now..

On a side note, is there any particular reason TL074s are used here? I’ve been under the impression that TL07x are well suited for audio and TL08x are better for CVs..

Cheers!

8

you rock man. It was the cable length. I left it extra long for debugging purposes, when I chopped it down it started talking to the DAQ chip. It did NOT work at 3.3V but sprang to life at 5. I can totally see why you are using the buffer with your external box now..

On a side note, is there any particular reason TL074s are used here? I’ve been under the impression that TL07x are well suited for audio and TL08x are better for CVs..

Cheers!

What cable lenght are you using now?

9

yes, this would be very interesting!

Which cable length did you use before, which length is it now?

What is the difference between a TL07x and TL08x?

Best Regards, Thorsten.

10

The TL084 has better DC performance (low offset) and the TL074 has better noise/distortion performance.

Working length was ~ 10" (from ~2 ft)

11

Alright, thanks!

Btw.: for those who grew up with the metric system: cable length was 60 cm, now it’s ca. 25 cm 38 cm, now it’s ca. 17 cm

Best Regards, Thorsten.

12

Revising those lengths (i was guessing from memory earlier)

Original bad length: 38 cm

New good length: 17 cm

I was using a 32 gauge grey ribbon cable that I use for everything so that may be in play also. Will go to something a little better for the final assembly for sure (I’m quite fond of SmashTV’s ribbon cable)