#372

I believe 2. Anymore and you might want to look into powered bus options.

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#373

it has two headers but the pullups are sufficient to support numerous devices on the bus.

“powered bus” is a weird misnomer for i2c, since there is no “power” — it’s just data lines.

the reason the “powered ii bus board for TT” exists is because the resistors need to be pulled up to the positive rail, and the old rev TT had low pullups which limited the number of bus devices. so in addition to adding extra ports, it also lowered the pullup, which required “power”, but it actually doesn’t “use” power.

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#374

perfect! i2c is an elegant solution for that problem.i had no idea its misnomer was powered bus. thank you Brian and Jake :slight_smile:

#375

It’s not really a misnomer; power is used during the transitions from low to high. The “pulling” of the pull-up is moving a small charge “uphill” and that requires energy. The microcontroller dumps that charge back down the hill. In other words: if you ran your pull-ups using a battery, it would eventually be drained.

In fact-- [gets elbowed in the ribs] oof

#376

lol yes of course

the misnomer is “you need more power for more devices on the bus” which is what i was attempting to disabuse

3 Likes
#377

Hey everyone I need some help troubleshooting my teletype build. I’ve flashed the firmware successfully and now just can’t get the terminal screen to come up. On boot up I get the “all scenes will be deleted” text and then a black screen. TR1, 3, AND 4 remain lit as seen in the picture. I’ve spent the afternoon making sure my joints are good but still no luck. Just looking for any advice on where to look. Thanks so much! 20201030_165312|281x500

#378

If you hold the button during this message, does it continue to the live prompt? This message is displayed and boot is prevented as a protection measure before resetting Teletype’s flash storage to its default state, which happens after any firmware update. This is documented here.

1 Like
#379

Thank you so so much! Of course it was right in front of me the whole time. At least I can say I’ve fully checked the entire circuit and know everything is soldered properly :sweat_smile:

#380

The 2.2uF caps that I have at home are rated 10 VDC. The bom calls for 25VDC. They are C9, C48, C55 and located in the VDDCORE/VDDOUT, but I don’t know how much voltage is going around here. Is 10vdc rating of my caps sufficient? (my orders from Mouser just shipped before I realized :frowning: )
EDIT: since VDDcore/out are around 1.65-1.95V, the 10vdc caps will be fine

#381

and how long are the screws you use go through the panel, 4mm spacer, screenPCB, into the 6mm spacer. Is 8 enough? or better a bit larger?

#382

A bit longer: 9-10 should be okay.

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#383

I have read both that Grid should NOT be connected to Teletype and that it can if you have a newer revision. I just received a DIY version built from a Pusherman PCB. Would it be ok to connect Grid to this directly?

#384

Yes, it’s ok but very likely to be noisy and might not support a 100% fully-lit Grid. You should probably use a ground loop adapter for powering the Grid externally. If you are DIY handy it is easy to hack together two USB cables to achieve the same effect.

1 Like
#385

Cool. Didn’t want to burn my new module or anything. Hacking a USB cable would probably be doable. I’ve seen the discussion on this.

#386

you won’t damage the module - worst case scenario it will shut down and you can just power cycle. but you do need to make sure you have sufficient power in your eurorack case if you plug it directly. you need at least 500mA available on 5V rail.

1 Like
#387

my teletype is working nicely, upon following the first teletype study everything seemed to work. When I started study 2, I had to use the param knob in order to scroll through the scenes, but it stayed at scene 31. And sometime it seemed to glitch to another value, but go immediately back to scene 31. Connection of the pot to ground, 3.3v and path of lug2 goes to CVin1 via a resistor. So where might there by problem? With the pot, i can change CV-IN1 from 0V to 2.5V. So that seems ok?

or does it need to be calibrated before the param knob works? just started reading about this

#389

did replacing U3 also solved your problem with PARAM and IN ?

#390

Yes, it did fix my problems.

#391

hello there, today I was using my diy teletype and kept encountering an issue where the CV outs stopped working. Powercycling my synth solved the issue temporarily but it would sometimes come back as I continued to play with the same script. I’m guessing it is some sort of overheating issue but I also found some other threads talking about firmware bugs that caused such things.

Anyone else here encounter issues with the CV out DAC stops working? Given my module is diy it is hard to know if it is a build issue or a firmware issue.

#392

And do you know what the problem was with your U3 ? Because I’m afraid I’ll destroy things when I’ll try to replace 2 chips (U3 and U4). How can I be 100% sure that the fault is with both chips, and not some resistor or capacitor?
I hadn’t checked before, but my CV1,2,3 and 4 are also not working (together with PARAM and IN) . TR1-4 work fine and trigger ins also.