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

Posted by remmy on 2016-07-21 14:29

One thing CubeMX developers can do to help is to add some comments
to CDC_Receive_FS to say it is a callback function and that you should copy
out the data presented in Buf (of length Len) to your own buffer before it gets
lost with next data arriving through USB. Also hint Len is maximum APP_RX_DATA_SIZE.

(Aside - the code in previous post seems to have had the hash in hash defines replaced by numbers
Thats just the interpreting the hash as numbered indented points - ignore it and use hash symbols for hash defines)