Posted on May 17, 2011 at 13:08I have an application that runs on a STM32F103 which is essentially a USB virtual COM port for Windows. It adheres to the USB Communication Device Class Abstract Control Model standard. I am running into a problem with Bulk OUT transactions; my endpoint packet size is set to 64 bytes. If the overall transfer is greater than 64 bytes, intermittently one of the maximum size (64 byte) packets will generate the normal Correct Transfer Received interupt but when I read the number of bytes using the GetEPRxCount() from ST’s USB library it reports 63 bytes. I have a USB protocol analyzer so I know all the bytes are sent by the host (Windows). No errors are reported in the interrupt status register, and all 64 bytes are there if I force a 64 byte read in this situation.
Has anyone else encountered this problem ?
