USB endpoint freezes

Hello everyone,

please help me find the solution to this problem:

I'm writing a composite device firmware for an Atmel SAM7S256 mcu. The firmware incorporates a usb keyboard and a HID. Because I have only 4 endpoints to use with this MCU, I am assigning 1 endpoint (EP1) to the keyboard interface, and 2 endpoints (EP2 (in) and EP3 (out)) to the other interface.

The problem is that when I write to EP3, my host program hangs (probably because the firmware hangs too). My firmware is an adaptation of the Atmel provided sample keyboard firmware. The composite device enumerates just fine (keyboard + HID).

What could be wrong?

I don't know enough of the AT91 usb stack to understand IF I have to change anything else in the code to add those 2 endpoints to the second interface. My understand is that this change would be enough:

typedef struct { USBConfigurationDescriptor configuration; // first interface USBInterfaceDescriptor interface0; HIDDescriptor hid0; USBEndpointDescriptor interruptIn0; // second interface USBInterfaceDescriptor interface1; HIDDescriptor hid1; USBEndpointDescriptor interruptIn1; USBEndpointDescriptor interruptOut1;
} __attribute__ ((packed)) HIDDKeyboardDriverConfigurationDescriptors;

Here's my understanding of how HID device works: when the device firmware receives a SET_REPORT request on the control EP, it reads the content of the control EP and makes a call to USB_Read() passing the number of the endpoint to read and a call back function. So, I am checking the content of the interface #, and if it is 1, I pass the EP3 to USB_Read(). But this mechanism doesn't seem to be working for me. :(

Please help me out with any hints. Is Tsuneo still in the forum?

Thanks a million.
Paulo