Digispark CDC library doesn't work

[maxgerhardt]

Tested with the reference sketch

https://github.com/ArminJo/DigistumpArduino/blob/master/digistump-avr/libraries/DigisparkCDC/examples/CDC_LED/CDC_LED.ino

Uploading works fine, but as soon as the bootloader exits and the USB CDC device is supposed to be created..

Translated: "USB device was not recognized. The last USB device that has been connected to this computer, did not work ordinarily and wasn't recognized by Windows."

Device manager says

"The USB device has returned an invalid USB configuration descriptor".

Tested board is the http://digistump.com/products/1

Selected Arduino IDE settings

Drivers were installed as per https://github.com/ArminJo/DigistumpArduino#driver-installation.

[maxgerhardt]

Very interesting: the DigisparkKeyboard/Keyboard.ino demo works and the computer recongizes the USB device. But not with the CDC sketch..

[maxgerhardt]

The DigiUSB/DigiBlink.ino works as well.

But not the CDC :/

[d-a-v]

FWIW, CDC (serial port) works but is very unstable under Linux (it makes eventually the Linux general host USB stack hang).

[ArminJo]

@d-a-v Thanks for the info.
I never tested CDC and do not know the development state, I just delivered the original digistump version.

[maxgerhardt]

The same behavior occurrs btw with the original core (https://github.com/digistump/DigistumpArduino/).

There are some forum topics about this (http://digistump.com/board/index.php/topic,2720.msg13422.html#msg13422) with some posts like

DigiCDC is an ugly hack, as CDC devices are specified as Hi-Speed USB (12 MHz clock). The Digispark USB emulation is Lo-Speed USB (1.5 MHz clock). It worked anyway on Windows XP and on older Linux kernels, but with newer versions of Windows and Linux it does not work anymore.

Another post (http://digistump.com/board/index.php/topic,2321.msg13159.html#msg13159) talks about deactivating Windows's driver signing and installing a magic driver (https://github.com/protaskin/LowCDC-Win10x64). I don't want to risk a BSOD like in the issue of that repo though 😅.

[ArminJo]

So I think, it is a good idea to extend the examples with these links and a warning. I will do this...

Update: Done 😀

[GiorgosXou]

Is there any alternative way of serial communication directly from usb? or at least any other possible software based way, except from deactivating Windows's driver signing? (I'm looking for a way to communicate between a Digispark and a PC's USB port)

^{it’s been bugging me for hours now..}

[d-a-v]

Has anyone ever tried TinyUSB with this core ?

[GiorgosXou]

Personally, I wish i could but my knowledge on this subject is quite a bit baffled... and so I'm not that sure about how i could manage to get it working right now [...]

[maxgerhardt]

The general DigisparkUSB and also DigisparkCDC library use V-USB as the underlying USB library, and it also has a few words on CDC

CDC requires bulk endpoints which are forbidden for low speed devices by the USB specification. However, most operating systems don't care and CDC works

which we don't observe here.. so I'm not sure if any USB CDC actually works on modern operating system with non-hacked drivers with the low-speed AVRs.

On the other hand, here's a echo example, from what I see it uses a generic HID USB class here. The USB functions HID set report and HID get report are used to transfer data to the device. And this looks like a nice easy tool to send and receive HID reports for data exchange. Maybe you can even use libusb or some python libs.

[wujiang]

Not working for me either. Anyone has any recommendations for some similar libraries?

[simonovich]

I recommend cleaning the chip manually first.
It seems to me that this does not happen when writing firmware from Arduino IDE

This command will clear the chip.
Specify your details for paths, port and port speed:

~/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino18/bin/avrdude -e -c arduino -p t85 -P /dev/ttyUSB0 -b 19200 -C ~/.arduino15/packages/arduino/tools/avrdude/6.3.0-arduino18/etc/avrdude.conf

Then return to IDE and try flashing the chip again.

[maxgerhardt]

@simonovich so you have the situation that it does work in the Arduino IDE but not over PlatformIO, or have you not tested it via PlatformIO?

[simonovich]

have you not tested it via PlatformIO?

Sorry, I don't know anything about PlatformIO.
I did it in Arduino IDE

[amckinlay]

None of the DigisparkCDC examples are working on macOS. Please remove them. There is no way to get Arduino's Serial Monitor to work.