I guess it is a hardware question... I've built a V-USB device on Attiny85 - typical bus-powered 5V scheme with two zener diodes on D+ and D-. I do have two caps (electrolytic 10uF and ceramic 0.1uF) between +5V and GND. The USB cable I am using has five wires (usual four plus the shield that is connected to the outer shell of USB connector). I tried leaving the shield wire floating and connecting it to the ground on my board - no difference.
It works fine, but is very sensitive to static discharge on computer case. Basically, every time I touch the metal on my laptop case, the USB device stops communicating. The client app reports:
and /var/log/syslog shows
This is definitely not normal - e.g. my USB mouse does not get disconnected when I touch my computer.
Any ideas how I can fix it?
It works fine, but is very sensitive to static discharge on computer case. Basically, every time I touch the metal on my laptop case, the USB device stops communicating. The client app reports:
- Warning: cannot query manufacturer for device: error sending control message: Protocol error
Could not find USB device!
and /var/log/syslog shows
- usb 4-1: usbfs: USBDEVFS_CONTROL failed cmd usbDisplay rqt 128 rq 6 len 256 ret -71
This is definitely not normal - e.g. my USB mouse does not get disconnected when I touch my computer.
Any ideas how I can fix it?