AN02058: xcore.ai SPI slave boot£££doc/rst/an02058.html#an02058-xcore-ai-spi-slave-boot

AN02058: xcore.ai SPI slave boot$$$Introduction$$$Restrictions and limitations£££doc/rst/an02058.html#restrictions-and-limitations

• The XTC SPI Boot Tools are provided for Windows 11 Pro hosts only

• The example has been validated on Windows 11 Pro hosts

• The example has been validated on the xcore.ai device

• Loading of LPDDR and SWMEM are not supported

AN02058: xcore.ai SPI slave boot$$$SPI slave image file processing$$$Data blocks£££doc/rst/an02058.html#data-blocks

The following data blocks are sent over the SPI slave interface to boot the xcore.ai. The Delay after block send field defines the time-delay that must be inserted (with SPI Slave Select de-asserted) after the block has been sent.

These blocks and their delays are extracted from the SPI slave image file generated by the xboot tool.

The Data block name and Delay after block send fields are referred to in the tables below.

The SPI slave image file is a binary file and its format (schema) is defined in the next section. All values are little-endian. This image file must be processed to extract the data blocks and inter-block delays defined in the table above.

All delay values extracted from the SPI slave image file are in units of nanoseconds.

AN02058: xcore.ai SPI slave boot$$$SPI slave image file processing$$$Data block extraction£££doc/rst/an02058.html#data-block-extraction

The SPI slave image file comprises the following contiguous data sections, with the data blocks to be transmitted and the associated delays embedded in these data sections.

AN02058: xcore.ai SPI slave boot$$$SPI slave image file processing$$$Data transmission£££doc/rst/an02058.html#data-transmission

Each byte of the data blocks extracted from the SPI image file must be bit-reversed before being sent over the SPI interface to the xcore.ai.

The data must be transmitted over the SPI interface according to the timing diagrams below.

The host SPI master may have a limit on the data that may be transferred in a single transaction (with SPI SS continuously asserted). It may break up a data transfer request by a software into a sequence of tranactions, with SS de-asserted between these transactions.

The SECONDARY_LOADER data block must be transferred in a single tranaction, with SPI SS asserted. This data block is small in size so the single tranaction requirement can be met by hosts.

Subsequent data blocks may be broken into multiple tranactions.

AN02058: xcore.ai SPI slave boot$$$Example application$$$XTC Tools 15.5.1 Commnand Prompt£££doc/rst/an02058.html#xtc-tools-15-5-1-commnand-prompt

In the steps below, an XTC Tools 15.3.1 Command Prompt must be used.

Check the xboot tool is available by running:

xboot --version

If this tool is not available, go back to the section Installing the XTC SPI Boot Tools to extract the contnents of tools\Microsoft_xboot_1_0_0__XTC_15_3_1.zip into the XTC 15.3.1 installation.

AN02058: xcore.ai SPI slave boot$$$Example application$$$Building the example£££doc/rst/an02058.html#building-the-example

This section assumes that the XMOS XTC Tools have been downloaded and installed. The required version is specified in the accompanying README.

Installation instructions can be found here.

Special attention should be paid to the section on Installation of Required Third-Party Tools.

In addition to the XMOS XTC Tools 15.3.1, the contennts of the file tools\Microsoft_xboot_1_0_0__XTC_15_3_1.zip must be exctracted into the existing XTC Tools 15.3.1 installation directory tree.

The application is built using the xcommon-cmake build system, which is provided with the XTC tools and is based on CMake.

The an02058 software ZIP package should be downloaded and extracted to a chosen working directory.

To configure the build, the following commands should be run from the XTC command prompt:

cd an02058
cd app_an02058
cmake -G "Unix Makefiles" -B build

All required dependencies are included in the software package. If any dependencies are missing, they will be retrieved automatically during this step.

The application binaries should then be built using xmake:

xmake -j -C build

Binary artifacts (.xe files) will be generated under the appropriate subdirectories of the app_an02058/bin directory — one for each supported build configuration.

For subsequent builds, the cmake step may be omitted. If CMakeLists.txt or other build files are modified, cmake will be re-run automatically by xmake as needed.

AN02058: xcore.ai SPI slave boot$$$Example application$$$Running the example£££doc/rst/an02058.html#running-the-example

The example code can be loaded via an XTAG and run to ensure it functions. From an XTC command prompt, the following command should be run from the an02058/app_an02058 directory:

xrun bin\app_an02058.xe

AN02058: xcore.ai SPI slave boot$$$Example application$$$Generating a SPI image£££doc/rst/an02058.html#generating-a-spi-image

From an XTC command prompt, the following command should be run from the an02058/app_an02058 directory.

Run the xboot tool with the command:

xboot -o bin\app_an02058.xboot --target-file XK-EVK-XU316-xboot.xn bin\app_an02058.xe

This step creates the SPI slave image file app_an02058.xboot.

When using the xboot tool to generate an image from an .xe program, the file XK-EVK-XU316-xboot.xn must be supplied using the --target-file option.

AN02058: xcore.ai SPI slave boot$$$Example application$$$Booting the xcore.ai device£££doc/rst/an02058.html#booting-the-xcore-ai-device

Python example scripts are provided to boot the xcore.ai, using an FTDI FT232H device in the adapter board Adafruit FT232H Breakout acting as a SPI master, connected to a Windows host.

A Command Prompt must be used to run the Python example scripts. Python 3.12 must be on the PATH of the Command Prompt. This Python installation must have the modules usb and pyftdi. These are typically installed by running the commands:

pip install usb
pip install pyftdi