The TNKernel USB bulk firmware is the USB bulk device driver for TNKernel real-time OS. Current version of the USB bulk firmware supports Philips LPC214x ARM-based microcontrollers.  

  There are two main groups of operations in USB bulk firmware - support USB Control (Endpoint 0) and support of the bulk data reception/transmission.

1. Endpoint 0 Control Requests Processing 

   The control transfers processing (Chapter 9 of the USB specification) is a mostly independent of the hardware (see file tn_usb_req.c). The TNKernel USB firmware supports the 9 required requests. The SYNCH_FRAME and SET_DESCRIPTOR requests are not supported (these put device to the forced stall condition)

2. Bulk Endpoints Transfer processing 

  The USB is a block device and to reach maximal bulk data transfer rate, the data have to be transferred by the 64-byte packets. The TNKernel USB bulk firmware uses a fixed size 64-bytes packets only. For the variable length data, you can use any of a well-known technologies for a block device drivers. 

2.1 Transfer without DMA (Philips LPC214x)

   The each endpoint has an associated data queue and a fixed-sized memory pool with the own task for the operations.

   For the IN endpoints (transmission) the each data queue's entry contains a pointer to the memory block (64 bytes) with the data to transmit. A memory blocks are managed by the fixed-sized memory pool.
   An each IN token causes a hardware interrupt. In the interrupt handler, if the data queue's is not empty (there are data to transmit) then the data is entered into the hardware transmitter and a memory block is released. Otherwise, there are no a data for the writing to the transmitter and the hardware automatically sends the NAK answer to the host.

   For the OUT endpoints (reception) the each data queue's entry contains a pointer to the empty memory block (64 bytes) to store receiving data. A memory blocks are managed by the fixed-sized memory pool.
   The each OUT request causes hardware interrupt. In the interrupt handler, if there is a free memory block for the reception, then the firmware reads a data from the hardware receiver to the memory block. A pointer to the memory block is sent into the data queue.
   The reception task waits the data from the receiver data queue by the TNKernel tn_queue_receive() function.   

 2.2 Transfer with DMA (Philips LPC2146/8)

   The each endpoint has an associated data queue and a fixed-sized memory pool with the own task for the operations.

   For the IN endpoints (transmission) the each data queue's entry contains a pointer to the memory block (64 bytes) with the data to transmit. A memory blocks are managed by the fixed-sized memory pool.

   There are two DMA interrupts for each IN transaction:

     - end_of_transfer (transmission of data block is finished)
     - DD_request (descriptor_request) - new DMA memory block should be set for transmission.

   In the transmission's end_of_transfer interrupt handler, the firmware just clears an interrupt flag for the normal hardware operations.
   In the transmission's DD_request interrupt handler, the firmware checks a data queue. If a data queue is not empty (there are data to transmit), the firmware selects a new DMA memory block for the transmission and copies data from the queue's memory block to the DMA memory. A queue's memory block is released.
   If the data queue is empty (there are no data to transmit), the firmware sets as active a special DMA memory block with the  no_packet parameters. When the DMA engine makes a processing for the block, it sends the NAK answer to the host.

   For the OUT endpoints (reception) the each data queue's entry contains a pointer to the empty memory block (64 bytes) to store receiving data. A memory blocks are managed by the fixed-sized memory pool.

   There are two DMA interrupts for each OUT request:

     - end_of_transfer (data is ready in DMA memory)
     - DD_request (descriptor_request) - new DMA memory block should be set for receiver

   In the reception's end_of_transfer interrupt handler, the firmware gets a free memory block from the fixed-sized memory pool and the data is copied to this memory block from the DMA memory. A pointer to the memory block is sent into the receiver's data queue.
   The reception task waits the data from the receiver's data queue by the TNKernel  tn_queue_receive() function.
   When a data arrives, a reception task makes the user data processing. Then a memory block is released and the DMA interrupt (actually, data reception) is enabled for this endpoint. Until a DMA endpoint interrupt is disabled, the hardware automatically sends the NAK answer to the host for each OUT request.
   In the reception's DD_request interrupt handler, the firmware checks a free memory block availability in the fixed-sized memory pool. If there is no free memory block, a DMA interrupt is not enabled (it means the NAK answer to host). If there is free memory block, the firmware sets a new DMA memory block for the reception and enables a DMA endpoint interrupt (the data reception).

3. USB  VID and PID

   For the TNKernel USB bulk firmware tests, a dummy VID = 1237(hex) & PID = ABCD(hex) are used (see the file tn_usb_descr.c).

4. PC USB driver and test software   

   The TNkernel USB has been tested with the USBIO - USB host driver for Windows from Thesycon(r) (http://www.thesycon.de). 
   The demo version of the driver can be used for 4 hours. Then all function calls will be rejected and the computer must be rebooted in order to use the demo again.
   A free USBIO Development Kit Demo includes Installation Wizard, USBIO Cleanup Wizard and test application (it is used for all TNKernel USB tests).

5. PC USB driver installation  

5.1. Install a demo version of USBIO – USB Development Kit for Windows *.exe file from Thesycon(r) (http://www.thesycon.de)

5.2. Load the test firmware into the Philips LPC2146/48 FLASH - either with or without DMA

5.3. Open the Windows Device Manager (Control Panel -> System -> Hardware -> Device Manager or  Start Menu -> Run and then type 'devmgmt.msc'

5.4. Connect an USB cable from the PC to the development board
  A message 'Found New Hardware TNKernel USB' in the desktop tray should appear and in the Windows Device Manager's list the new record 'Other devices -> TNKernel USB' should be added.
   Close a Windows Driver Installation Wizard window (Windows invokes it automatically). It is not used here.

5.5. From an USBIO installation directory, run the USBIO's own Installation Wizard  - USBIOwiz.exe
   Select the device  '>>Unknown<<  |  TNKernel USB'  from the list and press a button  'Next'.
   After the finishing of the process, in the Windows Device Manager's list you shell see a record 'USBIO controlled devices -> USBIO Device VID=1237 PID=ABCD'.
   Close the USBIO Installation Wizard application.

6. TNkernel USB bulk firmware tests 

   There are two sets of the base test firmware:

      - in the firmware's directory 'LPC2146'         - a test application without DMA.
      - in the firmware's directory 'LPC2146_DMA' - a test application with DMA.

   The test firmware creates a 2 bidirectional bulk pipes by the LPC214x's USB Endpoint 2 and Endpoint 5.
   An each physical endpoint has the own task to operate.

6.1 Preparation of the tests

6.1.1  Load the test firmware into the Philips LPC2146/48 FLASH;

6.1.2  From the USBIO installation directory, run the USBIO test application (it is used for all TNKernel USB firmware tests) - USBIOAPP.EXE.
   In the main window on the page 'Device', select in the listbox 'Available Devices' device's entry (for the single USBIO device, it will be the entry 'Device 0') and press a button 'Open'. Check all operations results by the messages in the  'USBIOAPP Output Window'. 
  On the page 'Configuration' press a button 'Set Configuration'. the LED on Test Board should stop flickering.
  On the page 'Pipes', the all four firmware endpoints have to be in the listbox 'Active Endpoints'.

 6.2 Test N 1 - Checking speed of  'PC to USB device'  data stream 

  In the firmware test N1, the Endpoint 5 RX (Bulk OUT Pipe 0x05) receives the data from the PC.

  In the main window on the page 'Pipes', in the listbox 'Pipes' select the '0x05 Bulk OUT' and press a button 'Read from File and Write to Pipe' - a new dialog window is opened.  
  In the dialog window 'USBIOAPP - Bulk OUT Pipe 0x05' open the page 'Buffers' and set 'Size of Buffers' - 4096, 'Number of Buffers'- 4.
  On the page 'Write from File to Pipe' choose a source file (any, but it is recommended to use a file with size of few megabytes) and press a button 'Start Writing'. 
  After a few seconds of transmission, the value of a transfer speed in the editbox 'Mean data rate' will be stable.

6.3 Test N 2 - Checking speed of 'USB device to PC' data stream 

   In the firmware test N2, the Endpoint 2 TX (Bulk IN Pipe 0x82) sends a data in the text format by the 64-byte packets.

  In the main window on the page 'Pipes', in the listbox 'Pipes' select the entry '0x82 Bulk IN' and press a button 'Read from Pipe and Write to File' - a new dialog window is opened.
  In the dialog window 'USBIOAPP - Bulk IN Pipe 0x82' open the page 'Buffers' and set 'Size of Buffers' - 4096, 'Number of Buffers'- 4.
  On the page 'Read from Pipe to File' choose a destination file and press a button 'Start Reading'. 
  In the editbox 'Mean data rate' you shell see the transfer speed value. Do not stop a reading immediately because the measurement takes a few seconds.

  You can check a destination data file's contents with any text viewer/editor. An each text line in the file starts with the 12-digit ASCII number and has following spaces up to the line end. A total line length is 64 bytes  - 62 bytes of the text + 2 bytes for the '\r\n'.The  ASCII numbers must be in the '+1' sequence from line to line without dropping.

6.4 Test N 3 - Checking speed of loop-back data transfer

   In the firmware test N3, the Endpoint 2 (Bulk OUT pipe 0x02) and the Endpoint 5 (Bulk IN pipe 0x85) are used for the loop-back data transferring - the data, that the Endpoint 2 RX receives from the PC, are sent to the Endpoint 5 TX for the transmission back to the PC (in the firmware, there is a separate data queue for this purpose).

  In the main window on the page 'Pipes', in the listbox 'Pipes' select the entry '0x02 Bulk OUT' and press a button 'Read from File and Write to Pipe' - a new dialog window is opened.
  In the main window on the page 'Pipes', in the listbox 'Pipes' select the entry '0x85 Bulk IN' and press a button 'Read from Pipe and Write to File' - a new dialog window is opened.
  In the both dialog windows open the page 'Buffers' and set 'Size of Buffers' - 4096, 'Number of Buffers'- 4.
  In the dialog window 'USBIOAPP - Bulk IN Pipe 0x85', on the page 'Read from Pipe to File' choose a destination file.
  In the dialog window 'USBIOAPP - Bulk OUT Pipe 0x05', on the page 'Write from File to Pipe' choose a source file (any, but it is recommended to use a file with size of few megabytes ).
  Uncheck the checkbox 'Rewind at and of file'.
  Press a button 'Start Reading'.
  Press a button 'Start Writing'.
  After finishing of the transfer, press a button 'Stop reading'  (the writing is terminated automatically).
 
  You can compare both files (the source and the destination) - they must have the same length and contents.

7. Data transfer performance tests 

7.1.  Environment:

7.2.Raw data transfer (no OS, just send/receive dummy data)

7.3. TNkernel USB bulk firmware (with TNKernel v.2.1) examples

    Firmware tests:  - usb_test1 (without DMA)
                            - usb_test2 (with DMA)