stm32f207 usb only multiple of 64 bytes can be send

[easylwl]

Posted on April 10, 2013 at 10:04

change by stm32 usb device VCP example:

my send function: uint16_t VCP_DataTx (uint8_t* Buf, uint32_t Len) {  uint8_t i;  for (i=0;i<64;i++)    //only multiple of 64 bytes can be send   {  APP_Rx_Buffer[APP_Rx_ptr_in] = g_ucaHeartbeat[i];  APP_Rx_ptr_in++;       /* To avoid buffer overflow */    if(APP_Rx_ptr_in == APP_RX_DATA_SIZE)    {      APP_Rx_ptr_in = 0;    }    } return USBD_OK; } the  usbd_cdc_core.c function DCD_EP_Tx (pdev,                VL8461_IN_EP,                (uint8_t*)&APP_Rx_Buffer[USB_Tx_ptr],                USB_Tx_length);    //the USB_Tx_length must be 64 ?? please help #stm32f207-cdc-virtualcom-usb #duplicate-thread

[Andrew Neil]

Posted on April 10, 2013 at 12:12

There's no need to repeat the same question in every section of the forum:

/44864166

[tsuneo]

Posted on April 10, 2013 at 17:20

You may send any size of transfer over single DCD_EP_Tx() call, even more than 64 bytes (for full-speed) or 512 bytes (for high-speed) (*1). The stack and the USB engine split a large-size transfer into full-size transactions.

When the transfer size is just the multiple of endpoint wMaxPacketSize (64 / 512), you'll need to call DCD_EP_Tx(buf_len=0) to terminate the transfer with ZLT (Zero-Length Transaction), by the requirement of the CDC bulk endpoint. (*1) The upper limit comes from PKTCNT field (10bits) of OTG_FS_DIEPTSIZx and OTG_HS_DIEPTSIZx registers. upper limit = wMaxPacketSize * (2^10 - 1) wMaxPacketSize = 64 bytes (FS) or 512 bytes (HS) Tsuneo

[easylwl]

Posted on April 11, 2013 at 03:25 thank you. but I found the DCD_EP_Tx() the buf_len must be multiple of 64,if I want to transfer  8 bytes,By setting the DCD_EP_Tx(buf_len=8),it  will be nothing receive from the PC software (BUSHOUND) ?  

[easylwl]

Posted on April 11, 2013 at 03:30

and if I want to send 64 bytes ,by setting DCD_EP_TX(buf_len=64) ,it will be successful

.what wrong with me ?

[easylwl]

Posted on April 15, 2013 at 11:17

I change the USB CDC device Configuration Descriptor like this

/*Configuration Descriptor*/   0x09,   /* bLength: Configuration Descriptor size */   USB_CONFIGURATION_DESCRIPTOR_TYPE,      /* bDescriptorType: Configuration */   USB_CDC_CONFIG_DESC_SIZ,                /* wTotalLength:no of returned bytes */   0x00,   0x01,   /* bNumInterfaces: 1 interface */   0x01,   /* bConfigurationValue: Configuration value */   0x00,   /* iConfiguration: Index of string descriptor describing the configuration */   0xC0,   /* bmAttributes: self powered */   250,   /* MaxPower 2 mA */      /*Data class interface descriptor*/   0x09,   /* bLength: Endpoint Descriptor size */   USB_INTERFACE_DESCRIPTOR_TYPE,  /* bDescriptorType: */   0x00,   /* bInterfaceNumber: Number of Interface */   0x00,   /* bAlternateSetting: Alternate setting */   0x02,   /* bNumEndpoints: Two endpoints used */   0xff,   /* bInterfaceClass: USER */   0x00,   /* bInterfaceSubClass: */   0x00,   /* bInterfaceProtocol: */   0x00,   /* iInterface: */     //18     /*Endpoint OUT Descriptor*/   0x07,   /* bLength: Endpoint Descriptor size */   USB_ENDPOINT_DESCRIPTOR_TYPE,      /* bDescriptorType: Endpoint */   0x03,                        /* bEndpointAddress */   0x02,                              /* bmAttributes: Bulk */   0x40,  /* wMaxPacketSize: */   0,   0,                              /* bInterval: ignore for Bulk transfer */   //25   /*Endpoint IN Descriptor*/   0x07,   /* bLength: Endpoint Descriptor size */   USB_ENDPOINT_DESCRIPTOR_TYPE,      /* bDescriptorType: Endpoint */   0x82,                         /* bEndpointAddress */   0x02,                              /* bmAttributes: Bulk */   0x40,  /* wMaxPacketSize: */   0,   0                               /* bInterval: ignore for Bulk transfer */   //32 and change device decriptor __ALIGN_BEGIN uint8_t USBD_DeviceDesc[USB_SIZ_DEVICE_DESC] __ALIGN_END =   {     0x12,                       /*bLength */     USB_DEVICE_DESCRIPTOR_TYPE, /*bDescriptorType*/     LOBYTE(0x0200),                       /*bcdUSB 2.0*/     HIBYTE(0x0200),      2,    //0xff,                       /*bDeviceClass*/     0x00,                       /*bDeviceSubClass*/     0x00,                       /*bDeviceProtocol*/     USB_OTG_MAX_EP0_SIZE,      /*bMaxPacketSize*/     LOBYTE(USBD_VID),           /*idVendor*/     HIBYTE(USBD_VID),           /*idVendor*/     LOBYTE(USBD_PID),           /*idVendor*/     HIBYTE(USBD_PID),           /*idVendor*/     0x00,                       /*bcdDevice rel. 2.00*/     0x02,     0,    //USBD_IDX_MFC_STR,           /*Index of manufacturer  string*/     0,  //USBD_IDX_PRODUCT_STR,       /*Index of product string*/     0,  //USBD_IDX_SERIAL_STR,        /*Index of serial number string*/     USBD_CFG_MAX_NUM            /*bNumConfigurations*/   } ; /* USB_DeviceDescriptor */

[tsuneo]

Posted on April 15, 2013 at 16:12

[i]> but I found the DCD_EP_Tx() the buf_len must be multiple of 64[/i]

Heh, how did you get to such a wrong finding? You don't need to modify the descriptors at all. Rather, to apply DCD_EP_Tx() to the bulk IN EP directly, copy usbd_cdc_core.c to your project folder, and modify it. \STM32_USB-Host-Device_Lib_V2.1.0\Libraries\STM32_USB_Device_Library\Class\cdc\src\usbd_cdc_core.c usbd_cdc_core.c calls DCD_EP_Tx() on the bulk IN endpoint, to keep transfer interval.  - maybe, ST has tried to implement ''latency timer'', but their implementation is just a delay, not a ''latency timer''. You have to delete this implementation. This implementation is useful for USB-UART and printf() over VCP, but for direct buffer transfer using DCD_EP_Tx(), it disturbs operation. Modify these subroutines. [code] usbd_cdc_core.c static uint8_t  usbd_cdc_SOF (void *pdev) {       /*    Delete all of contents of this subroutine */   return USBD_OK; } static uint8_t  usbd_cdc_DataIn (void *pdev, uint8_t epnum) {   // replace   USB_Tx_State = 0;   return USBD_OK; } [/code] DCD_EP_Tx() is applied, for example, as follows. [code] extern uint8_t USB_Tx_State; extern uint8_t APP_Rx_Buffer[APP_RX_DATA_SIZE]; int main(void) {   ...   ...   /* Main loop */   while (1)   {     if (i++ == 0x100000)     {       STM_EVAL_LEDToggle(LED1);       STM_EVAL_LEDToggle(LED2);       STM_EVAL_LEDToggle(LED3);       STM_EVAL_LEDToggle(LED4);       i = 0;       APP_Rx_Buffer[0] = 'x';       if ( (USB_OTG_dev.dev.device_status == USB_OTG_CONFIGURED) && (USB_Tx_State == 0 ) ) {         USB_Tx_State = 1;         DCD_EP_Tx (&USB_OTG_dev, CDC_IN_EP, (uint8_t*)&APP_Rx_Buffer, 1);       }     }   } } [/code] Tsuneo

[sergalyant]

Posted on December 06, 2014 at 09:53

how to make it in the new library? DCD_EP_Tx() and usbd_cdc_core.c is missing