WB_BOOTLOADER - Configurable Wishbone Flash SPI Bootloader (Version 1)

The Flash SPI Bootloader component (WB_BOOTLOADER) provides the ability to automatically load (or bootstrap) from serial Flash memory on the Desktop NanoBoard NB2DSK01. The device provides the interface between the NB2DSK01'S SPI bus and independent SRAM on the daughter board. Provided the device is enabled for boot operation, then as soon as the design is programmed into the daughter board FPGA (or an external reset is issued if already programmed) the content of the serial Flash memory device will be copied into the SRAM.

The device is configurable in that you can specify where in SRAM the content copied from the serial Flash memory is to be written, and the size of the memory involved in the copy.

The WB_BOOTLOADER can also be used as a standard SPI Controller, with an optional interface to a processor in your design, enabling the processor to communicate with slave SPI-compatible devices external to the FPGA in which the design is running. Operating as an SPI Controller, the device is functionally identical to the SPI_W peripheral.
 

 
You must ensure that the required embedded code has been loaded into the serial Flash memory. This can be performed manually from the Instrument Rack - NanoBoard Controllers panel. For information on the programming procedure involved, see Using SPI Flash Memory as Embedded Memory.

Alternatively, you can download a design directly from an SD card inserted into the NB2DSK01 motherboard's SD card reader, through use of an EXAMPLE file (*.example). The programming file referenced in this file will be downloaded to the FPGA on the daughter board, and the referenced HEX file will be programmed into the serial Flash memory device, U22.

You could take this process a step further by setting the NB2DSK01 to automatically boot using an EXAMPLE file stored on an inserted SD card, on power-up.

For more information on EXAMPLE files and downloading/booting from an SD card, see Interacting with the Desktop NanoBoard NB2DSK01.

Features at-a-glance

• Bootloading functionality – copy code from serial Flash memory on the NB2DSK01 motherboard into SRAM on the daughter board

• Configurable from the OpenBus System document or Schematic sheet
   
  • Specify start address in SRAM at which to write content copied from serial Flash
  • Specify the size of memory to be copied
     
• Optional use as SPI Controller peripheral (identical to SPI_W)
   
  • Full duplex
  • Serial clock signal configurable for polarity, phase and frequency
     
• Ability to bypass bootloading functionality and operate solely as an SPI Controller

• Wishbone-compliant

Availability

From an OpenBus System document, the SPI (Bootloader) component can be found in the Peripherals region of the OpenBus Palette panel.

From a schematic document, the WB_BOOTLOADER component can be found in the FPGA Peripherals (Wishbone) integrated library (FPGA Peripherals (Wishbone).IntLib), located in the \Library\Fpga folder of the installation.

Designing with the WB_BOOTLOADER

Use the following links to explore use of the WB_BOOTLOADER in more detail:

See Also