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I need to transfer 64 bytes of Interrupt In transfer to PC via AVR. The function usbSetInterrupt is able to transfer only 8 bytes at a time.Using it 8 times to transfer 64 bytes does not seem to be a solution. There is a line in usbdrv.h "If you need to transfer more bytes, use a control read after the interrupt." in the description of usbSetInterrupt.

What is control read and how to transfer more interrupt in data using this method??

Hi Madara.

VUSB only implements low-speed USB. In low-speed USB the standard forces:

[...]
The maximum data payload size for low-speed devices is 8 bytes.
[...] (from: http://www.beyondlogic.org/usbnutshell/ ... #Interrupt)

So, you can not implent sth. the standard does not allow.

BR matrixstorm

The maximum data payload size is 8 bytes for Control transfers as well.However we are able to transfer upto 254 bytes in VUSB by transferring them in a chuncks of 8 bytes in single control requests. I was wondering if this could be done for interrupt tranfers as there is a little description as "If you need to transfer more bytes, use a control read after the interrupt." in the description of usbSetInterrupt.

You can not transfer that much data in one go but of course you can do it by chunks in interrupt transfers.


while (!usbInterruptIsReady()){usbPoll(); } usbSetInterrupt( reportBuffer, 8 );
while (!usbInterruptIsReady()){usbPoll(); } usbSetInterrupt((void *)&reportBuffer + 8, 8 );
while (!usbInterruptIsReady()){usbPoll(); } usbSetInterrupt((void *)&reportBuffer + 16, 8 );
ect...