USBasp is a small circuit to flash atmel processors which uses the USB port, but since the USB communication isn't a feature available in the processor by default, it must use the V-USB firmware/drivers to deal with it.
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| Never ever do this for the USB data lines ! |
After assembling the circuit i had a few problems trying to understand why it did work on a older machine and didn't work on my recent laptops, using dmesg on the newer laptops I got these messages:
[ 7486.876197] usb 3-2: device descriptor read/64, error -71
[ 7487.105059] usb 3-2: device descriptor read/64, error -71
[ 7487.320153] usb 3-2: new low speed USB device using uhci_hcd and address 4
[ 7487.441052] usb 3-2: device descriptor read/64, error -71
[ 7487.664184] usb 3-2: device descriptor read/64, error -71
And with the older machine using the lsusb command:
Bus 003 Device 016: ID 16c0:05dc VOTI shared ID for use with libus
It seems the usb controler was unable to read the device description, but after an week and some google searches i found that the electromagnetic interference affects a lot with the circuit. To reduce this problem i rewired the circuit and replace the usb port with a short usb male cable instead of the female port and the problem was fixed. (And the circuit also works fine with an usb extension cable)
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It appears that the Intel USB controller is more exigent with the quality of the signal than the SiS controller !
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