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FPGA Autoloading

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Jon Szymaniak edited this page Jul 20, 2014 · 35 revisions

Overview

There are currently two ways to have the FPGA automatically loaded when you begin using the bladeRF: a host-software based mechanism, and a firmware-based mechanism.

These "autoload" mechanisms alleviate the need to manually load the FPGA via the bladeRF-cli or using the bladerf_load_fpga() function.

Host software-based

As of version 0.16.0, libbladeRF provides a mechanism to load an FPGA when a device handle is opened, if the FPGA is detected to not already be in a configured state.

This approach is generally recommended over the firmware-based mechanism for users who will always be using the bladeRF device with a host machine.

Upon opening a device handle, libbladeRF checks the device's FPGA size. It then searchs for the corresponding FPGA bitfile (hostedx40.rbf or hostedx115.rbf) in one of the following locations. The order in which these locations are searched is from top to bottom.

Linux or OSX

  • your_home_directory/.config/Nuand/bladeRF/
  • your_home_directory/.Nuand/bladeRF/
  • /etc/Nuand/bladeRF/
  • /usr/share/Nuand/bladeRF/
The user's home directory is determined based upon contents of /etc/passwd.

Windows

  • %APPDATA%/Nuand/bladeRF/
Simply place (or symlink, for *nix users) the FPGA bitfile in one of these directories and it will be loaded when you first open the device handle.

Firmware-based

Another option is to write an FPGA-bitstream to the device's SPI flash. When the firmware boots, it checks for the presence of FPGA metadata, and will begin to load the FPGA if a bitstream is present.

This process is slower than the host-based mechanism mentioned above. However, this mechanism allows for "headless" (without a host PC) operation. It takes approximately 4 seconds to load an x40 image, and ~12 seconds to load an x115 image. Speeding this process up is a pending development task.

Important: Be sure that the firmware autoload has completed before attempting to use the device (i.e., open a device handle)! When the FPGA is fully configured, LEDs 1-3 will be lit.

The FPGA may be written to the bladeRF's SPI flash via the CLI: 

bladeRF-cli -L path/to/hostedx(size).rbf

To disable this autoload mechanism, erase the FPGA image and metadata. This can also be done via the CLI: 

bladeRF-cli -L X

IMPORTANT: It is highly recommended that you disable FPGA autoload when prior to upgrading device firmware in order to avoid any potential conflicts.

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