Can see Mojo V3 on Com3, but can't erase/program


I have an old Mojo V3. When I plug the USB cable into my Windows 10 computer, I can see “USB Serial Device (COM3)” in Device Manager. However, when I use the Alchitry Loader to ‘Erase’, I get “Status: Connecting…” and it stays there. I have to kill the program through Task Manager and on the second time I try to erase, I get “Status: Looking for Mojo serial port…” Any ideas on what I might need to do to connect to the device?


Using Alchitry version 1.2.7 this problem has been solved under windows.

On the Alchitry website, the aforementioned version is no longer available for download, I don’t know why.

Under linux I have never had problems with the serial port.

Just changing the original download link from “” to “” seems to provide a 1.2.7 installer. I have not tested it, but the file downloaded fine.

Thanks for the response.

I remembered that it might have something to do with the Bootloader. Here is a picture of the pins I shorted. I thought it might have to do with the Bootloader on the AVR ATmega.

Before I shorted the pins, I was able to see a COM3 on AVRDUDESS. Afterwards, I didn’t see COM3 on AVRDUDESS and my Windows machine suddenly recognized that the ATMega32u4 was connected (see picture).

So, still looking into it. Progress is slow though and I have other projects I’m working on though too!

Thanks for any ideas!
BTW, the Alchitry Loader that I’m using on Windows is 1.2.7. I am just trying to erase it. My version of ISE is 14.6, which doesn’t seem to work with Alchitry Loader. So I’ll have to upgrade that before I can do some work on that. On my Linux box, I have ISE 14.7 and haven’t been able to connect with the MOJO either… so I’m thinking there might be an issue with the MOJO that I have.

Surely the problem is the hardware modification.

Now you see ATmega32U4 in DFU which is certainly not COM Port mode.

Eliminate the hardware change and see what happens.

I had the same problem, but I managed to fix it. So what I’ve done?
Firstly download newest version 1.2.7 of Alchitry Labs.
Then when I connected Mojo to win10, it automatically found some drivers and call it Mojo in the device manager. This is where the root of problem. You may delete it or keep, but the thing is that you need to install driver from the Alchirty Labs folder(there you may find files : dpinst-amd64.exe or dpinst-x86.exe).
If you have not english language for your win10, you will see the problem that driver can’t be installed in not supported language. To fix it you need to update dpinst.xml and remove and tags there. Perhaps you may delete the whole language section, I didn’t test it. After all these manipulations it began to work properly(I can write to mojo, and I can see serial monitor in the IDE without crashing)