Pheetuz
Full Member level 3
Hi folks,
I am working on a project that involves bootloading over USB using a homemade design based upon the Teensy arduino board.
I am sure that my processor is working, however, when I connect the board via USB and open the windows device manager there is an unknown device there with error code #43, sometimes the USB device doesnt even show up in the device manager - this lead to me probing the USB differential pair, the results of which didnt look great...
As you can see the signal is a bit of a state. I guess it's really not surprising that the PC is failing to communicate with it. From what I have read online I think I may have made a mistake with the track layout, I only really paid attention to the fact that the tracks were the same length when laying the board out, not to the impedance of the tracks or the shape of the routing itself
The circuit and PCB layout are as follows:
As you can see, I have used a 33 ohm termination resistor for each part of the USB pair but also I have not really done a great job of laying out the tracks themselves.
Does anyone with experience working with USB think that the track layout at present is the cause of my problems? If so, do you think it would be possible for me to connect wires directly from the chip pins bypassing the termination resistors to the USB connector. Can I change the termination resistance? Add some parallel capacitance? Anything that I can do to get this prototype up and running?
Cheers in advance folks!
/Pheetuz
I am working on a project that involves bootloading over USB using a homemade design based upon the Teensy arduino board.
I am sure that my processor is working, however, when I connect the board via USB and open the windows device manager there is an unknown device there with error code #43, sometimes the USB device doesnt even show up in the device manager - this lead to me probing the USB differential pair, the results of which didnt look great...
As you can see the signal is a bit of a state. I guess it's really not surprising that the PC is failing to communicate with it. From what I have read online I think I may have made a mistake with the track layout, I only really paid attention to the fact that the tracks were the same length when laying the board out, not to the impedance of the tracks or the shape of the routing itself
The circuit and PCB layout are as follows:
As you can see, I have used a 33 ohm termination resistor for each part of the USB pair but also I have not really done a great job of laying out the tracks themselves.
Does anyone with experience working with USB think that the track layout at present is the cause of my problems? If so, do you think it would be possible for me to connect wires directly from the chip pins bypassing the termination resistors to the USB connector. Can I change the termination resistance? Add some parallel capacitance? Anything that I can do to get this prototype up and running?
Cheers in advance folks!
/Pheetuz
