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STM32F103 USB VCP receives only byte by byte

Question asked by klimavicius.laur.001 on Jan 17, 2014

Maybe anyone have met with situation or have any hints where to look for problem if I receive data in "EPx_OUT_Callback()" function only by one byte, even if it was sent significantly larger amount of it.

USB irq handler is taken from V4.0.0 USB-FS-Device library - "VirtualComport_Loopback" project.

Everything else seems to be working fine - performance not yet tested, device is recognized, using "CDC_Send_DATA()" function data to PC is transmitted in packets up to 63 bytes per packet. Bet when it comes to receiving info sent by PC - in "EP3_OUT_Callback()" I receive only packets of len == 1, if string sent from PC is longer than 1B it is received only as multiple transmissions of len == 1.

Any offers where to start looking for problems?