midibox64 CC weirdness, and why it's bad to crosspost

[gzifcak]

yes, all the unused ain inputs and all the unused inputs to the core are grounded.

this problem is not happening randomly, it's only when i turn the pots. at first it seemed like it was sending data with 0 values from other pots, but there are also some messages mixed in that are not assigned to the pots.

thanks

[/tilted/]

OK, so having actually looked at your data, I think this problem may well go away with the upgrade to 10k pots.

I think that having such a low total resistance on your power rails is pulling the rails themselves together, and introducing noise to your pots as they do so.

[stryd_one]

omg. I didn't read the thread, or I would have known you had 1K pots, and then I would have told you to build it as designed ;)

[gzifcak]

ok, great. thanks guys.

when i was getting ready to build, i rummaged through my pots and these 1k were the perfect size and i had enough of them i searched the forums and found a message by thorsten recommending 1k to 10k.

hopefully the 10k pots will do the trick.

[stryd_one]

Well you're right!:

The internal ADC of the PIC doesn't measure the resistance of the pot, but a voltage at the slider ("middle pin"). Regardless if you are using a 1k, 5k or 10k pot, the voltage at the slider is always within the 0V - 5V range, and this is ok for the PIC.

Resistances between 1k and 10k are ok.

Lower resistances will consume too much power

Higher resistances will lead to jittering output values

I cannot recomment 100k pots because of the high impedance, the current drain will be so low that external noise can influence the measuring results too much. The result: jittering pot values. So, best values are around 1k and 10k.

because this is the recommented impedance for the ADC suggested in the PIC18F datasheet. 1k..10k should be ok, linear curve is a strict requirement. If you buy pots which don't meet the spec, you could notice jittering MIDI values.

I dunno..... I'm still suss about your pots :( Are you sure yours are linear?

[/tilted/]

I think the 1k should be considered a minimum value, only to be used if you have only a few pots.

1k pots are probably fine if you have 1-8 pots. more than this may cause problems.

[tt]

64x 1k  parallel = 15.625 ohms.  current @5V supply = 320mA

64x 10k parallel = 156.25 ohms.  current @5V supply =  32mA

8x 1k  parallel = 125 ohms.    current @5V supply =  40mA

[/tt]

so you can see that in terms of supply load, there is quite a difference.

I'd say you definitely want to keep your total parallel load up around the 125 ohms or more range (< 40mA).

[gzifcak]

cool, thanks. now i'm just waiting for the 10k pots to arrive so i can swap them out.

[stryd_one]

so you can see that in terms of supply load, there is quite a difference.

Great summary, thanks tilt. I added it to the wiki, hope that's cool with you.

[gzifcak]

ok, i installed the 10k pots. my resistance looks good, but i'm getting tons of midi data shooting out of the midibox:

TIMESTAMP IN PORT STATUS DATA1 DATA2 CHAN NOTE EVENT             

0003EBED  1  --    90    4D    00    1  F  5 Note Off             

0003EBEE  1  --    90    4E    00    1  F# 5 Note Off             

0003EBEF  1  --    9F    4F    00  16  G  5 Note Off             

0003EBF7  1  --    B0    5B    00    1  ---  CC: Reverb Depth     

0003EBF8  1  --    B1    5B    00    2  ---  CC: Reverb Depth     

0003EBF8  1  --    B2    5B    00    3  ---  CC: Reverb Depth     

0003EBF9  1  --    B3    5B    00    4  ---  CC: Reverb Depth     

0003EBFA  1  --    B4    5B    00    5  ---  CC: Reverb Depth     

0003EBFB  1  --    B5    5B    00    6  ---  CC: Reverb Depth     

0003EBFC  1  --    B6    5B    00    7  ---  CC: Reverb Depth     

0003EBFD  1  --    B7    5B    00    8  ---  CC: Reverb Depth     

0003EBFE  1  --    B8    5B    00    9  ---  CC: Reverb Depth     

0003EBFF  1  --    B9    5B    00  10  ---  CC: Reverb Depth     

0003EC00  1  --    BA    5B    05  11  ---  CC: Reverb Depth     

0003EC01  1  --    BB    5B    04  12  ---  CC: Reverb Depth     

0003EC01  1  --    BC    5B    03  13  ---  CC: Reverb Depth     

0003EC02  1  --    BD    5B    01  14  ---  CC: Reverb Depth     

0003EC03  1  --    BE    5B    08  15  ---  CC: Reverb Depth     

0003EC04  1  --    BF    5B    00  16  ---  CC: Reverb Depth     

0003EC05  1  --    B0    5D    00    1  ---  CC: Chorus Depth     

0003EC06  1  --    B1    5D    00    2  ---  CC: Chorus Depth     

0003EC07  1  --    B2    5D    00    3  ---  CC: Chorus Depth     

0003EC08  1  --    B3    5D    00    4  ---  CC: Chorus Depth     

0003EC09  1  --    B4    5D    00    5  ---  CC: Chorus Depth     

0003EC0A  1  --    B5    5D    00    6  ---  CC: Chorus Depth     

0003EC0B  1  --    B6    5D    00    7  ---  CC: Chorus Depth     

0003EC0C  1  --    B7    5D    00    8  ---  CC: Chorus Depth     

0003EC0D  1  --    B8    5D    00    9  ---  CC: Chorus Depth     

0003EC0E  1  --    B9    5D    00  10  ---  CC: Chorus Depth     

0003EC0F  1  --    BA    5D    00  11  ---  CC: Chorus Depth     

0003EC10  1  --    BB    5D    00  12  ---  CC: Chorus Depth     

0003EC11  1  --    BC    5D    00  13  ---  CC: Chorus Depth     

0003EC13  1  --    BD    5D    00  14  ---  CC: Chorus Depth     

0003EC13  1  --    BE    5D    00  15  ---  CC: Chorus Depth     

0003EC14  1  --    BF    5D    00  16  ---  CC: Chorus Depth     

0003EC15  1  --    B0    4A    00    1  ---  CC: Brightness       

0003EC16  1  --    B1    4A    00    2  ---  CC: Brightness       

0003EC17  1  --    B2    4A    00    3  ---  CC: Brightness       

0003EC18  1  --    B3    4A    00    4  ---  CC: Brightness       

0003EC19  1  --    B4    4A    00    5  ---  CC: Brightness       

any ideas? does this mean i have a bad pot? all the unused inputs are grounded.

thanks,

greg

[gzifcak]

...and now i'm getting nothing but the startup sysex message. hmmm.

[gzifcak]

when i re-upload mios, mios studio gets the right response messages, but then i get no messages when i upload an app, and no data from the pots.

any ideas?

thanks

[gzifcak]

ok, found a wiring problem; i had my + and gnd wires going to one set of 8 pots twice, instead of once to each set. so i guess the ungrounded pots were causing the streams of data.

but now that i've fixed the wiring, i'm still not getting anything, after uploading the mios successfully and sending applications (the midibox does not respond to the application uploads). i get the upload request on power up, but then nothing at all. voltage is what it should be at the regulator and at the pots.

ideas?

[bugfight]

akk, if you had random data coming into the analog ins while uploading mios, you might have messed up the pic.  i haven't had this happen myself, but several folks have reported similar issues in the chat.

even if this is the case, you might still be able to save it.  maybe someone who has done it can give you the magic reset formula.  or you could try reburning the bootloader a few times, and then make sure analog ins are grounded while uploading...

(hehe, hmmmmmmmm the 1k pots weren't the issue, who woulda thunk it? *whack*)

[gzifcak]

well, i don't get any random data when uploading the mios. i get all the normal checksum responses and mios studio says it's completed successfully. it's just when uploading apps, i get no response from the midibox.

i think the 1k pots were the cause of the problem i was having before, but now i'm just not seeing anything come out of the box after the startup upload request. i've uploaded mios numerous times and tried uploading many different midibox64 apps with midi-ox. i'm sure the settings in midi-ox match the instructions for uploading.

[bugfight]

... and tried uploading many different midibox64 apps with midi-ox. ...

you should also upload the app from mios studio...

[gzifcak]

i can't figure out how. when i go to sysex send/receive, it shows me a little window that says ***TODO***. does that mean it's not implemented yet?

thanks

[bugfight]

just use hex file upload

[gzifcak]

just tried it. it only lets me browse for hex files, but i typed in the path and sent it. no dice. it says upload process complete, but no change in the midibox (non)behavior.

thanks

[bugfight]

no i mean use the hex file, chat is better for this kinda thing...

[gzifcak]

ok, got it running in the chat, thanks to bugfight. it's definitely more stable with the 10k pots, but my old problem still exists to some degree:

-turning one pot occasionally sends data for another pot.

-after hooking it to a synth, i can hear that this behavior often results in parameters randomly resetting to zero

-turning a single pot often sends values that jump around for that CC. usually i can wipe smoothly from 0-127 with no glitches, but often the parameter seems to reset itself to 0.

-no data is ever sent unless a pot is being turned. so it definitely seems to be the analog ins that are hooked up to the pots, and not the other ains.

further ideas?

thanks,

greg

[stryd_one]

Sounds like a short on the AIN serial connections. You mentioned that it is intermittent, so have a look for maybe dry solder joints, or very fine bridges.

[gzifcak]

thanks! are these the inputs or the connections to the core? i'll go over both right now.

[stryd_one]

Sorry I meant the connections to the core, and inbetween your AINx4 modules. I think you can test this with the SRIO test app too.

[gzifcak]

well, i've just re-checked and resoldered my connections i don't know how many times, and even rewired the connections between the ain and the core, and still no luck. it will be fine for a good 15 turns of a pot, then all of a sudden it'll start sending zeros whenever i move it.

looks like the SRIO app is for the din/out.

i'm almost tempted to buy the doepfer pocket electronic kit and swap it out with the midibox boards.

[stryd_one]

Uhm, so you have a different problem now?