LPC1837 Xplorer board  interrupt transfer not working for endpoint4

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by tonymeng66 on Thu Nov 05 02:05:27 MST 2015
    I am trying to setup for interrupt transfer on my LPC1837 Xplorer board as a device. I use the following API in the ROM stack

           uint32_t (*WriteEP)(USBD_HANDLE_T hUsb, uint32_t EPNum, uint8_t *pData, uint32_t cnt); 

in a thread that gets executed periodically so whenever I receive a request from the host , the buffer data I wrote can be read.

This works well for EP1 and EP2 but not for EP4. Can anyone tell me what do I miss here ? Why cant I simply change the EPNum to realize interrupt transfer on EP4?
I checked the datasheet that EP4 does support interrupt transfer.