On 08/07 11:21, Stefan Mark wrote: > On Sun, 6 Aug 2017 18:50:07 +0200 > tu...@posteo.de wrote: > > > Hi, > > > > sorry, this will become a little longish... > > > > Background: To program an ATMEL ATtiny85 via USB > > without a dedicated USB chip there is a bootloader > > called "micornucleys", which bitbangs the USB protocoll. > > This mechanism is used in Digistupms Digispark ATTtiny > > developmnent board (http://digistump.com/products/1). > > > > So far so ....nice? > > > > When I plug in such a little board into my PC, demesg > > reports: > > [ 1429.834140] usb 7-4: new low-speed USB device number 15 using > > ohci-pci [ 1429.965142] usb 7-4: device descriptor read/64, error -62 > > [ 1430.203151] usb 7-4: device descriptor read/64, error -62 > > [ 1430.438161] usb 7-4: new low-speed USB device number 16 using > > ohci-pci [ 1430.569151] usb 7-4: device descriptor read/64, error -62 > > [ 1430.803174] usb 7-4: device descriptor read/64, error -62 > > [ 1431.038184] usb 7-4: new low-speed USB device number 17 using > > ohci-pci [ 1431.456157] usb 7-4: device not accepting address 17, > > error -62 [ 1431.582204] usb 7-4: new low-speed USB device number 18 > > using ohci-pci [ 1432.000209] usb 7-4: device not accepting address > > 18, error -62 [ 1432.000244] usb usb7-port4: unable to enumerate USB > > device > > > > or similiar. lsusb does not show anything related at all. > > > That usually happens when the improvised USB is not good enough. Try a > different port, maybe put a USB Hub between. Check if the resistors and > diodes for the level shifting are the right ones (measure the > resistors, especially if you are not using 5% types). If that does not > work, try a different diode/resistor combination (For example, usbasp > uses 5v6 zener and 68/2k2 resistor, littlewire 3v6 zener and 27/1k2 > resistor. I have seen others too. I had at least one which never > worked with my laptop).
The board is THAT tiny (http://digistump.com/products/1) that even a single proble will short circuit one half of the board... :) > > > As recommended on related pages on the internet, I installed > > dedicated udev rules to show the needed ttyACM device. But > > since the kernel itsself fails to accept the device, the best > > udev rules will not work. > > > > My first thought was: The micronucleus bootloaed is missing or > > is defective... > > > > But plugging in the board into my Android tablet (the tablet runs > > Lollipop and is nothing special at all beside being rooted) via > > an OTG cable and using lsusb after that, it shows > > Bus 001 Device 003 ID 16d0:0753 MCS Digistump DigiSpark > Some ports are more forgiving than others. These soft-usb-thingies tend > to be a bit rough, especially the level conversion seems to be a bit > icky :) > I have a usbasp which works always and everywhere i tested it just > perfectly. One of my littlewires is a bit wonky (it sometimes looses > connection and needs a few tries until it works again). Another one > works fine, but not on every device.
