Hello.

I am working on AT89C5131 and device recognized as HID keyboard by PC.
I need to make this device firmware upgradable.
I am going to make device boot and launch bootloader, and update flash by bootloader flash api and reboot and run user application. function or dll to do these seems to be provided by chip vender.
Currently there is 1 IN endpoint in my device because this only functions as keyboard. and I wonder if I should add another OUT endpoint, or add another interface or another configuration. firstly I thought I only need one OUT endpoint, but I doubt it now because my device is recognized as keyboard by PC.
I have read DFU(device firmware update) spec provided by USB organization saying that only control endpoint is required and I should add another configuration, but I need to use functions provided by chip vender. not following the spec.
I found windows application that connects to device, makes bootloader lauched, contols LEDs in the state that USB generic device program is on device. the program was generic USB device, not keyboard and had IN and OUT endpoints

Please inform me how I can do this.
Thanks.