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MIDIbox TIA - Atari 2600 Synth


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Just now, emerson said:

The green and white ones are correct, both pairs, and my meter tells me that the DIN pins and the DB25 pins for those are connected as you say.  Weirdly, DIN pin2 isn't grounded, even though the third wire from the MIDI Out cable goes to that pin.  I guess it didn't connect well when they made it, and I'm gonna have to take the connector apart more to debug that.

Don't worry it can work without ground. but it's molded connector on that side, strange. I maybe didn't connect the right wire color when I did it. but don't touch it let it ike that, it can work without if you don't use 15 meters MIDI cable

 

Just now, emerson said:

Hmm I used my PICkit clone to reprogram the bootloader into the PIC, and MPLAB reported success.  Now, though, when I put power to it while connected to MIOS Studio, it doesn't even give off the initial "f0 00 00 7e 40 00 01 f7" that it did previously.  I re-tried flashing the bootloader with MPLAB, and again it reported success, so the PIC is alive, at least, just not... doing anything.

Can you explain what you did exactly, files used etc...

Note: The jumper for MCLR is necessary for Core startup, put it back once you had burnt the pic.
image.png.993d6197031b1bbfc46b14be2143cc78.png

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2 minutes ago, Antichambre said:

Don't worry it can work without ground. but it's molded connector on that side, strange. I maybe didn't connect the right wire color when I did it. but don't touch it let it ike that, it can work without if you don't use 15 meters MIDI cable

OK good, I'll leave it alone.

2 minutes ago, Antichambre said:

Can you explain what you did exactly, files used etc...

After a couple of false starts, I got my PICkit clone's six pins connected to the jumpers as per the illustration.  I fired up MPLAB X IPE, selected device PIC18F4685, told it to power the PIC via the PICkit, connected successfully to the PIC, and selected bootloader_v1_2b_pic18f4685.hex from the mios_v19_h.zip archive from ucapps.de/mios_download.html.

It programmed just fine, said it succeeded with no errors.

My intent then was to get it talking to MIOS Studio to verify it was working, then upload MIOS itself and then finally the TIA app.  But now, it's not even spitting out the little sysex handshake blob that the bootloader normally sends at power-up time, and that it had been doing up until I started messing with MPLAB.  "Query" doesn't work at all, which I guess is to be expected.

Oh yes, I'd forgotten the jumper at first but did catch that error pretty early and put it back into the right place, with no luck.

I also did a second pass of connecting it to the PICkit, running MPLAB, and programming the bootloader hex file, which also alleged to complete successfully.

I'm gonna sleep on this and see if I find success tomorrow.  Thanks for walking through this with me so far.

Edited by emerson
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Tomorrow check for continuity and short-cut on the UART(MIDI) part of the circuit, mainly between optocoupler and pic, check resistors values, orientation of the diod, check also the orientation of the optocoupler(6N138), change it if possible...
here is the diagram, optocoupler is on top-right.... if you have a waveform monitor check the signal on RX path.

tia%20cartridge%20diagram.png?raw=1

Edited by Antichambre
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This is the third re-edit of this post because the bootloader and MIOS and setup_tia_cartridge.hex have *finally* all been successfully loaded (I reflowed a couple sketchy-looking solder joints, reseated the optocoupler a couple times, suddenly all is well with MIOS Studio).

So we're back to the initial problem, though with a new twist.  The MIDI In LED is staying on constantly, and now the "level" LEDs are lighting up in pairs, descending from the red ones to the bottom green ones (video below).

Further edit:  Actually hooked the box's audio up to see whether it's working despite no MIDI indicators.  It's not, but it is creating a -hellacious- burst of Atari-noise at the end of every LED cycle.  Also, weirdly, out here in the studio room, the MIDI In LED isn't lit.

18 hours ago, Antichambre said:

Eventually send a picture of the board(best reso as you can), I will maybe see something...

Forum server didn't like the size of the photos, so:

     https://hayseed.net/~emerson/TIA/

...has pretty good pix of the front and back, as well as a short video of the new LED behavior with the sound burst audible, though turned way down.

Edited by emerson
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16 hours ago, emerson said:

Further edit:  Actually hooked the box's audio up to see whether it's working despite no MIDI indicators.  It's not, but it is creating a -hellacious- burst of Atari-noise at the end of every LED cycle.

This is normal, this is the first startup sequence to init/format the banksticks(eeprom). But it must stop after a short moment.
 

16 hours ago, emerson said:

Also, weirdly, out here in the studio room, the MIDI In LED isn't lit.

Hummm. Check if it's working with the max-msp manager. or send a whole midi note range over channel 1...

Try also to upload this firm:
setup_tia_cartridge_keeze.hex
If I remember well @Keeze got the same issue.

 

Edited by Antichambre
add firmware used for keeze
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On 3/20/2021 at 9:06 AM, Antichambre said:

This is normal, this is the first startup sequence to init/format the banksticks(eeprom). But it must stop after a short moment.

Aha that's good info.  I let it run for a while, like 20min, and it kept going, so I'm having the hypothesis that my banksticks are at fault.  Knowing it's supposed to do that LED pattern, though, is heartening, we're getting somewhere at all finally.

I tried that other firmware without any change.  So to be clear, the one issue is that with one MIDI interface, it leaves the MIDI In LED on constantly.  With another, it doesn't.  Neither seem to respond to note-on or the like.

I'll also try the Max manager.  So far I've tried just the virtual keyboard that's part of MIOS Studio, without luck -- no MIDI LEDs lighting, no notes out, so I think it's just stuck in that initialize state and not fully starting.  (Edit:  Yeah the Max manager won't even connect.)

So, later I'm going to desolder the banksticks and try re-adding a fresh pair I have sitting around.  I remember I had trouble with the SMD soldering on this pair so I might have damaged them or have shorts hidden underneath them or something.

(Edit: fresh pair of banksticks had no effect, still stuck in the bankstick init LED loop.  Gonna keep looking around there.  Early testing shows that exactly the correct pins of the banksticks are connected to ground, still gonna work on testing others' connectivity to the right places.)

Edited by emerson
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  • 2 weeks later...

Well, I let it sit for a couple weeks and came back to it yesterday.  I've reflowed every solder connection (apart from the PIC itself), tested continuity all over the place, reflashed the TIA app a couple times, replaced the banksticks, and tried both MIOS Studio and the Max Manager to contact it while it's doing whatever it's doing.

When powered up, it blinks MIDI In and Out, then MIDI In comes on and the volume LEDs do the pattern that means bankstick init.  And there it stays, no matter how long I wait.

I've started to suspect that maybe the PIC itself is bad, or has a badly soldered pin maybe.  I got it preinstalled on the board from Modular Addict, so I haven't wanted to dig in there myself, especially since my SMD soldering skills are not great.  There's nothing obviously visibly wrong with its pins, so I feel like I'm starting to grasp at straws.

Anyone have thoughts on further debugging what the PIC thinks it's doing while it gets stuck in the "initialize bankstick" phase?

 

Edited by emerson
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  • 6 months later...

I'm experiencing the exact problem as emerson describes above with my build. On power up I get LED activity on the midi and a short burst of Atari noise that repeats indefinitely. Doing the test tone had no activity, and the interconnection test is the same (I made sure to have them on cartridge mode). I tripled checked everything but can't find any obvious problems. I got my board from Modular Addict as well. Any help would be appreciated.

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