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software/demo: Update README.md.

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Florent Kermarrec 2022-04-07 11:47:14 +02:00
parent 5222e7fc1a
commit fa611ba809
2 changed files with 33 additions and 7 deletions
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38
litex/soc/software/demo/README.md
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@ -3,16 +3,15 @@
This directory provides a minimal bare metal demo app that demonstrates how to easily create a bare metal C application and load it/run it on the CPU of a SoC.
[> Build
--------
[> Build and Load over LiteX-Term
---------------------------------
Imagine you just built the Arty example design from LiteX-Boards. Build the demo app as follows; where the build path is the path to your previously built Arty build directory:
To build a LiteX SoC for the Arty board (available in LiteX-Boards) and build the demo app for it, execute the following commands:
```
python3 -m litex_boards.targets.digilent_arty --build --load
litex_bare_metal_demo --build-path=build/arty/
```
[> Load
-------
Where `--build-path` is the build path to the Arty build directory. The Arty board is used here but almost any another board supported in LiteX-Boards could be used. When no external RAM is provided directly by the board, `--integrated-main-ram-size` argument could be used to add some integrated RAM in the SoC and be able to execute the demo from it. (ex `--integrated-main-ram-size=0x8000` will add 32KB of integrated RAM).
Loading the compiled demo app can be done in different ways as explain in LiteX's wiki:
https://github.com/enjoy-digital/litex/wiki/Load-Application-Code-To-CPU
@ -71,6 +70,33 @@ You should see the minimal demo app running and should be able to interact with
.--~~::::~:~~--,.
litex-demo-app>
[> Replace the LiteX BIOS with the Demo App
-------------------------------------------
In some cases, we'll just want to replace the LiteX BIOS with our custom app. This demo can be used as a basis to create a such custom app.
The demo will be recompiled to target the ROM of the SoC:
```
litex_bare_metal_demo --build-path=build/arty/ --mem=rom
```
The SoC can then be re-compiled to integrate the demo app in the ROM with:
```
python3 -m litex_boards.targets.digilent_arty --integrated-rom-init=demo.bin --build --load
```
When loading the bitstream, you should then directly see the demo app executed:
```
LiteX minimal demo app built Dec 10 2020 17:13:02
Available commands:
help - Show this command
reboot - Reboot CPU
led - Led demo
donut - Spinning Donut demo
litex-demo-app>
```
[> Going further
----------------
To create more complex apps, feel free to explore the source code of the BIOS or other open source projects build with LiteX at https://github.com/enjoy-digital/litex/wiki/Projects.

2
litex/soc/software/demo/demo.py
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@ -15,7 +15,7 @@ def main():
parser = argparse.ArgumentParser(description="LiteX Bare Metal Demo App.")
parser.add_argument("--build-path", help="Target's build path (ex build/board_name).", required=True)
parser.add_argument("--with-cxx", action="store_true", help="Enable CXX support.")
parser.add_argument("--mem", default="main_ram", help="Memory Region from which code will be executed.")
parser.add_argument("--mem", default="main_ram", help="Memory Region where code will be loaded/executed.")
args = parser.parse_args()
# Create demo directory