Odd situation with USB Communication Device (CDC )- VCP

Hi all,

I’m having an odd situation with RL-USB with the following characteristics:

STM23F407ZG (board with proven hardware)
Communication Device (CDC) – Virtual COM Port
Full Speed

CDC Config (in usb_config_FS.c):
#define USBD_CDC_ENABLE 1
#define USBD_CDC_EP_INTIN 1
#define USBD_CDC_WMAXPACKETSIZE 64
#define USBD_CDC_BINTERVAL 2
#define USBD_CDC_HS_ENABLE 0
#define USBD_CDC_HS_WMAXPACKETSIZE 16
#define USBD_CDC_HS_BINTERVAL 2
#define USBD_CDC_EP_BULKIN 2
#define USBD_CDC_EP_BULKOUT 2
#define USBD_CDC_WMAXPACKETSIZE1 64
#define USBD_CDC_HS_ENABLE1 0
#define USBD_CDC_HS_WMAXPACKETSIZE1 64
#define USBD_CDC_HS_BINTERVAL1 0
#define USBD_CDC_CIF_STRDESC L"USB_CDC"
#define USBD_CDC_DIF_STRDESC L"USB_CDC1"
#define USBD_CDC_BUFSIZE 64
#define USBD_CDC_OUTBUFSIZE 128

VCP is configured and recognized in Windows, communication work fine, but after sending a few thousand bytes (the amount varies) RL-USB just stops sending data over the USB, MCU keeps working normally and bytes are still receive over the USB interface.

After some debugging I found that “usbd_cdc_ser_availchar” is still being called, but usbd_cdc_ser_read is no longer called.

In order to isolate the problem, I made a project with only RL-USB and a very simple loop for sending and receiving bytes, and the situations remains the same, after a few thousand bytes sent RL-USB just stops calling usbd_cdc_ser_read … any ideas of what I'm doing wrong ?

Best regards,
Paulo