For a project I bought three Digistump ATtiny85 development boards. Got some other issues resolved but now two of them won’t connect, ie. no da Donk sound when Windows recognizes a new USB connection. To save plugging/unplugging I got a USB cable with a switch to cycle power to the board when it's upload time. I plugged one directly into the PC's USB port and there's no difference. I don’t believe they’re completely inop. (bricked) since one, which had a blink type program loaded still runs that after the startup delay however I can’t load a sketch to these two devices.
The error message:
> Device search timed out
Failed uploading: uploading error: exit status 1
Some searching revealed that a; this is not unknown for this board and, b; there’s a technique to "unbrick" these processors.
I have the materials on hand to build the high voltage programmer, if needed. Before I do that I’m asking the forum:
for an opinion whether this circuit could / will work on a development board with all its ancillary components in place.
whether just a plain vanilla Arduino as ISP (low voltage programmer) might do the same thing.
In either case I wouldn't be using the USB connections, I'd connect directly to the processor I/O ports.
I've built that HVP circuit and it works fine with a standalone ATtiny (or in my case, an ATtiny in a ZIF socket on a shield plugged into an Uno with the HVP sketch in it). The only signal I'd have any qualms about in your case is pin 2, PB3, SCI. R3 and D1 are going to aggresively try and keep SCI around 3.6V. With the series 1K resistor between the Uno and the ATtiny you've got a really nice voltage divider going on there. You could try it and see; there's sufficient series resistance that the Uno's output isn't going to be damaged.
If it doesn't work, and especially if this is a one off thing to unbrick it and then use it as normal again, temporarily removing R1 would probably do the trick.
It wouldn't be pretty but I could probably get R1 out. I don't have the equipment or skills to reinstall it so... If it doesn't work that's the end.
The currently preferred Arduino boards platform for Digispark support is the excellent TinyCore by MCUdude/Hansibull:
I saw that on my earlier thread and I did download it. However I have the Micronucleus working and didn't want to switch horses in the middle of the stream.
One thing that puzzles me is that Windows doesn't react at all when these boards are plugged in. There's no USB connect sound and no new device appears, so the ATtiny never seems to enumerate as a USB device.
Given that, is ISP or even HV programming really the next logical step, or does the complete lack of USB enumeration suggest a hardware problem instead?
Edit:
It might also be worth checking with USBDeview from NirSoft. If the board doesn't even appear there when plugged in, that would suggest it never starts USB enumeration, which seems more like a hardware or low-level firmware problem than an upload issue.
It's very curious. Board "A" has not yet stopped connecting. Board "B" and "C" both failed. After connecting "B" to the programmer (NANO) and attempting to upload the blink sketch nothing happened. When "B" was then reconnected direct to USB port it responded and would accept a sketch.
Same thing with "C", after connecting to programmer (with no upload attempt) "C" connected as USB device and accepts sketches.
I had the same habit while I had been downloading code into 8085/8086/8051 before meeting Arduino IDE which says "Upload". Arduino Team has enumertaed many many names which are not logical.
Just a thought: these boards seem unreliable. Even if you manage to get them working again, I wouldn't trust them in a real project. They're fine for tinkering, but I'd use different boards for anything important.
At some point, the value of further troubleshooting simply isn't worth the time invested.
Deprecation Warning: The Trinket bit-bang USB technique it uses doesn't work as well as it did in 2014, many modern computers won't work well. So while we still carry the Trinket so that people can maintain some older projects, we no longer recommend it.
Deprecation Warning: The Gemma bit-bang USB technique it uses doesn't work as well as it did in 2014, many modern computers won't work well. So while we still carry the Gemma so that people can maintain some older projects, we no longer recommend it.
These statements are for different products, but those products use the same "bit-banged USB" (V-USB) approach as the Digispark.
I haven't encountered any problems personally while using the Digispark, but I have only used mine for a few quick uploads performed as experiments when supporting users requesting assistance here.
