Hello everyone,
I've been using an Arduino UNO rev.3 as a programmer to send data over SPI to another Arduino UNO, in order to overwrite the bootloader. I'm using MiniCore, and I forgot to set the Bootloader to 'Yes' when uploading the SPI sketch on the programmer. I now can't communicate via USB with the programmer, and the target doesn't have a bootloader either. I'm currently looking for a way to flash the Arduino bootloader back on the programmer (I found this, but I couldn't manage to make it work: How to Flash Arduino Bootloader without a Programmer – Welldone Blog ). I know there are ISP programmers, but I'd like to know if there's a way to get the bootloader back on the UNO in my current situation.
A way to directly flash compiled .hex files could work I think (don't know if it's possible), but obviously the SPI method is preferred
Any kind of help is widely appreciated, thanks in advance! (please forgive my English, it's not my first language)
The rev 3 is the one with a removable 28-pin DIP chip, isn't it? You could buy a replacement atmega328 with the bootloader already flashed on eBay etc and fit that. The chip you remove can then be re-flashed with bootloader also.
Yes, it does have the removable chip.
I didn't think about this solution, I'll sure consider it. The part that interests me the most about your reply is that you're saying that I can re-flash the bootloader on the chip, but do you mean using the one bought with the bootloader to flash the bootloader on the removed one, or is there a way to directly flash the bootloader to the removed chip?
Thanks a lot for replying, best regards
Yes, get a programmer. I use USBAsp, they're cheap and readily available. Once you've got one, you won't need to bother using Uno as a programmer again, either.
In my experience, people who apologise for their English generally have no need to apologise, and that's certainly true in your case. Better than some who's first language is English, but paid no attention at school.
Did the UNO have the original UNO bootloader on it? If so, I doubt you uploaded anything to it with MiniCore set to "No Bootloader" since that requires an ISP programmer to do the upload, and doesn't even appear to use the correct baud rate for the bootloader when I try it here. In any case, you should not be able to overwrite the bootloader section of flash memory without an ISP programmer.
Select Tools > Board > Arduino AVR Boards > Arduino UNO and see if you can upload the example Blink sketch.
Turns out, it actually uploaded.
It makes sense, I think the issue may be elsewhere, i think i found the problem in the wrong place.
Yup. I didn't notice the double flashing of the LED on the programmer UNO board, the bootloader is actually still on there.
Hopefully it won't be a huge problem to find the actual issue there, thank you all for the help! Luckily I didn't order a programmer yet
Edit: it was a wiring issue, one of the jumper wires didn't connect well so it gave me an error of invalid device signature. Maybe this, with the fact that I noticed I set the Bootloader to "No Bootloader", made me thinking that I just overwritten the bootloader of the programmer.
Problem solved! (I'll set the solution as the reply of @CrossRoads , as it's the one which would hypothetically work in a case like the one described on the original post)
