Posted by remmy on 2016-07-21 11:28

Solved already

[As an aside, the CDC_Transmit_FS requires a check before being called:

char msg100;

sprintf(msg,”ARM reporting %i\n”)i++);
if (hUsbDeviceFS.dev_state == USBD_STATE_CONFIGURED)
CDC_Transmit_FS((uint8_t *)msg, strlen(msg));
]

And then static int8_t CDC_Receive_FS (uint8_t* Buf, uint32_t *Len) is a callback function
defined in usbd_cdc_if.c which gets called whenever there is data arriving
in USB through the virtual com port.

I modified the function to add 3 lines of code to copy out the incoming buffered data like this:

static int8_t CDC_Receive_FS (uint8_t* Buf, uint32_t *Len)
{
/* USER CODE BEGIN 6 */
USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf0);
USBD_CDC_ReceivePacket(&hUsbDeviceFS);

// This function CDC_Receive_FS is a callback function invoked when data is received - add 3 extra lines of code to copy the data to my own buffer
received_data_size = *Len;
memcpy(received_data, Buf, received_data_size);
receive_total += received_data_size;

return (USBD_OK);
/* USER CODE END 6 */
}

Further up the file usbd_cdc_if.c, I modified the data sizes and declared the 3 variables I am using

//#define APP_RX_DATA_SIZE 4
//#define APP_TX_DATA_SIZE 4

1. define APP_RX_DATA_SIZE 64
2. define APP_TX_DATA_SIZE 64

uint8_t received_data100;
uint32_t received_data_size;
uint32_t receive_total = 0;

in file usbd_cdc_if.h, I added 3 lines to export the three variables I am using:

extern uint8_t received_data[];
extern uint32_t received_data_size;
extern uint32_t receive_total;

In main.c I added #include “usbd_cdc_if.h”
and then printed out the receive_total and also the received_data.

It turns out the data is now received in blocks of 64 bytes
as decide in usbd_cdc_if.c by

1. define APP_RX_DATA_SIZE 64
2. define APP_TX_DATA_SIZE 64

Yippeee it works from CubeMX generated code compiled in AC6 with SW4STM32 toolchain