Hi folks.

As I'm making my mbed pretend it's a Sixaxis controller for PS3, it got me thinking. To configure the mbed as an USB device, wouldn't I be needing an external resistor, for either pullup/pulldown? I saw that it would need a single 1.5k pullup on D+ for other USB devices, would this be correct for mbed as well?

Regards, Lerche

When I connected the USB plug for the MCSFilesystem I didn't use any pull up resistors, just wires. I thought that the pull up resistors were included in the mbed schematic. Just curious ,where did you see the need for the 1.5K resistor??

I saw it on PIC18 schematics :-) There is a pullup resistor included on the mbed board, but will it connect? I don't know for sure :-)

Lerche

The resistor is used to tell the upstream USB hub what speed the connecting device is. It's included on the Mbed and is switched via a transistor connected to USB_CONNECTION/P2.9 pin on the LPC1768. So you can control the D+ line to say what speed device you are.

The LPC1768 manual describe this, as does the USB Spec (yeah, hardly bedtime reading but that's where you should be looking next).

Hi Christian, i'm migrating from PIC too, but i'm a little lost with mbed as a USB device, i want to use bulk transfer, but i'm not sure how to achieve this, i think i need to use usbdc.h and usbdc.cpp but i don't know how.

Can you point me in the right direction?

Thanks Ernesto.