Bulk transfer of Data via USB (Host side)

B) StellarisWare implementation
This implementation is based on StellarisWare 10630
First, host class instance and DriveOpen()/DriveClose() are easily made, modifying mass storage source code (copy/paste-global replace).

// printer host class instance
// and USBHPRNDriveOpen() / USBHPRNDriveClose()

typedef void (*tUSBHPRNCallback)(unsigned long ulInstance,
                                 unsigned long ulEvent,
                                 void *pvEventData);

typedef struct
{
    //
    // Save the device instance.
    //
    tUSBHostDevice *pDevice;

    //
    // Used to save the callback.
    //
    tUSBHPRNCallback pfnCallback;

    //
    // class specific members
    //

    //
    // Bulk IN pipe.
    //
    unsigned long ulBulkInPipe;

    //
    // Bulk OUT pipe.
    //
    unsigned long ulBulkOutPipe;
}
tUSBHPRNInstance;

static tUSBPRNInstance g_USBHPRNDevice =
{
    0
};

unsigned long
USBHPRNDriveOpen(unsigned long ulDrive, tUSBHPRNCallback pfnCallback)
{
    //
    // Only the first drive is supported and only one callback is supported.
    //
    if((ulDrive != 0) || (g_USBHPRNDevice.pfnCallback))
    {
        return(0);
    }

    //
    // Save the callback.
    //
    g_USBHPRNDevice.pfnCallback = pfnCallback;

    //
    // Return the requested device instance.
    //
    return((unsigned long)&g_USBHPRNDevice);
}

void
USBHPRNDriveClose(unsigned long ulInstance)
{
    tUSBHPRNInstance *pPRNDevice;

    //
    // Get a pointer to the device instance data from the handle.
    //
    pPRNDevice = (tUSBHPRNInstance *)ulInstance;

    //
    // Close the drive (if it is already open)
    //
    USBHPRNClose((void *)pPRNDevice);

    //
    // Clear the callback indicating that the device is now closed.
    //
    pPRNDevice->pfnCallback = 0;
}

And then, host driver instance

#define PRN_EVENT_OPEN          1
#define PRN_EVENT_CLOSE         2




static void *USBHPRNOpen(tUSBHostDevice *pDevice);
static void USBHPRNClose(void *pvInstance);




const tUSBHostClassDriver g_USBHostPRNClassDriver =
{
    USB_CLASS_PRINTER,
    USBHPRNOpen,
    USBHPRNClose,
    0
};

Copy these routines from usbhmsc.c, and replace all "MSC" with "PRN"
USBHPRNOpen() <- USBHMSCOpen()
USBHPRNClose() <- USBHMSCClose()

Delete this line from copied USBHPRNOpen() g_USBHMSCDevice.ulMaxLUN = 0xffffffff;

> now I would like to know how can I send data to printers using bulk transfers.

USBHPRNOpen() opens the bulk IN/OUT pipes.
Using the OUT pipe, the data on pBuffer is sent to the printer, as follows.
You may send any size of buffer, even greater than 64 bytes with single USBHCDPipeWrite() call.

    ulBytes = USBHCDPipeWrite(g_USBHPRNDevice.ulBulkOutPipe,
                              (unsigned char*)pBuffer, sizeof(pBuffer));

Tsuneo

Hi Tsuneo , I have already tried with USBHCDPipeWrite().I pass a string in this function and it prints only if the string ends with a carriage return () .

But how to print multiple strings in a single line . I tried writing the code in a for loop , now printer prints once in every 4 times command send.

I think there is garbage in pipes or not a proper HCD pipe write usage.

Regards,
Dhanush.

> I think there is garbage in pipes or not a proper HCD pipe write usage.

What is the PDL supported by the printer?
Before making such groundless assumption, you have to know printing protocol (ie. PDL)
In my first post, I said you should find the PDL before coding your firmware.

Tsuneo

Hi,

The Printer I am using is epson LX-300 and it supports ESC/P 9 pin PDL format. Can u please tell me now how should I go about this. The bold print and double print commands are working fine, I am facing the same problem discussed above.

The first time I send a string to be printed, it works. But the second time it prints garbage data.

Regards
Dhanush

Hi Tsuneo,

I successfully intterfaced the dot matrix printer using the details provided by you for LM3S5951 controller.
I am using an epson LX-300 printer which supports esc/p2 pdl.
now when eveytime I send data to printer preceded by an init printer command , the printer prints data.
But now when I send data w/o init printer command it prints data once in every two tries.
Please provide some solution.

Regards
Sanket K

Hi Tsuneo,

Now that I have successfully interfaced the printer using USB, everything is working fine.
I would also like to check whether the printer is busy or not like it has been checked using the 25 pin centronics using LPT. How could I achieve this I have one IN endpoint for the printer.

Regards
Dhanush

> I have one IN endpoint for the printer.

The bulk IN endpoint of the printer interface is optional.
It’s role is specific to each printer model.
Unfortunately, Epson doesn’t open the information of the role (protocol) over the bulk IN.
You may get some printer status, or nothing.
Try it.

ulBytes = USBHCDPipeRead( g_USBHPRNDevice.ulBulkInPipe, pBuffer, sizeof(pBuffer) );

> I would also like to check whether the printer is busy or not like it has been checked using the 25 pin centronics using LPT.

NAK on the bulk OUT endpoint corresponds to the BUSY signal of Centronics.

While the endpoint is NAKing, USBHCDPipeWrite() (and USBHCDPipeRead()) blocks the caller thread. I believe this is the reason why you need "BUSY" signal.

Instead of these blocking calls, you may apply non-blocking USBHCDPipeSchedule() to start transfer over the bulk IN or OUT endpoint.

USBHCDPipeSchedule( g_USBHPRNDevice.ulBulkOutPipe, pBuffer, sizeof(pBuffer) );
or
USBHCDPipeSchedule( g_USBHPRNDevice.ulBulkInPipe, pBuffer, sizeof(pBuffer) );

When the transfer finishes, callback is called for each endpoint.
This callback is registered at USBHCDPipeAllocSize() in your USBHPRNOpen()

static void PRNEndpointCallback(uint32_t ui32Pipe, uint32_t ui32Event);

static void *
USBHPRNOpen(tUSBHostDevice *pDevice)
{
    ...
    ...
                g_sUSBHMSCDevice.ui32BulkInPipe =
                    USBHCDPipeAllocSize(0, USBHCD_PIPE_BULK_IN_DMA,
                                        psDevice,
                                        psEndpointDescriptor->wMaxPacketSize,
                                        PRNEndpointCallback);    // <-------
    ...
    ...
                g_sUSBHMSCDevice.ui32BulkOutPipe =
                    USBHCDPipeAllocSize(0, USBHCD_PIPE_BULK_OUT_DMA,
                                        psDevice,
                                        psEndpointDescriptor->wMaxPacketSize,
                                        PRNEndpointCallback);    // <-------

In the callback,

static void
PRNEndpointCallback(uint32_t ui32Pipe, uint32_t ui32Event)
{
  switch ( ui32Event ) {
    case USB_EVENT_TX_COMPLETE:   // transfer on OUT endpoint finishes
      //
      // notify to the main thread by a flag, or start another transfer
      //
      break;

    case USB_EVENT_RX_AVAILABLE:  // transfer on IN endpoint finishes
      // read out data into a buffer
      USBHCDPipeReadNonBlocking( g_USBHPRNDevice.ulBulkInPipe, pBuffer, sizeof(pBuffer) );
      break;
    default: break;
  }
}

Tsuneo

Hi Tsuneo ,

I wish to interface a Laser printer (high USB speed device) to my ARM controller.But TIVA supports only low speed and full-speed devices . Is there any solution .Is there any interfacing circuitry ???

Regards,
Sanket

Hi Tsuneo,

I am sending data to the printer using usbhcdpipewrite. now i dont have the paper in the printer, the printer pauses, but its buffer is now full with the data that is sent. Now whenever I insert the paper it starts printing the data, but I dont want this to happen. But I have no other solution as busy line in LPT. Whether there is a solution to this or not.

Regards
Dhanush

Hi,

I am also facing the same problem with the printer. I want to check the paper out and set a flag in my code whenever there is no paper in the printer. My requirement is like this so I have to achieve this in any case . There may be a solution to this problem.

regards
Sagar

Hi Tsuneo,

Thank you for your responses. I have implemented the above things as said but whenever I read the status using GetPortStatus function described above I get result byte as '0' even if the paper is not present in the printer.

The procedure I followed for the same is as follows:

1: I added the implementation as discussed above to my printerhostclass.c file as it is. I understood the things mentioned in it.

2: I have created an instance of the printer driver g_ulPRNinstance.

3: unsigned long status=GetPortStatus(g_ulPRNinstance,0) I call the function using the above line from my main function. if((status & 0x20)== 1) do this else do that.

Now when I start the printer w/o paper and call this function then always it executes the "else" part, where as it should execute "if" part.
I check the value of status on uart but it shows 0. Am I doing something wrong here, if yes then what should I do

Dhanush

First off, you say you get the status '0'.
But the status is a number - not a character. While character '0' happens to be 0x20 + 0x10;

Next thing - your expression:

if((status & 0x20)== 1) { ... }

is broken. It can never be true.

It should either be:

if (status & 0x20) { ... }

or

if ((status & 0x20) != 0) { ... }