Read the documents in the F' repo as described in the README to get an understanding of the architecture.
This demo was developed on a Raspberry Pi 2 model B. The following directions are how to checkout and run the demo on the Raspberry Pi itself. There are also alternative directions for cross-compiling for the RPI. The cross-compile has been tested on Ubuntu as a host. Compiling and running on the RPI can be very slow, and the ground system has had some issues running on Raspberry Pi so this guide will walk the user through the setup to cross-compile for the raspberry pi.
From the RPI configuration menu:
- Enable SPI
- Enable UART
Disable use of the UART for the Linux console:
If the UART port is not set up correctly, there will be a file open error.
In order to see results via loopback, connect:
| Pin 1 | Pin 2 | Signal |
|---|---|---|
| TXD | RXD | UART |
| MISO | MOSI | SPI |
| IO23 | IO25 | GPIO |
| IO24 | IO17 | GPIO |
If you wish to see the blinking LED demo, connect an LED to GPIO 21 as follows:
Install the packages necessary to run the demo.
Please see INSTALL.md to ensure that the F´ application has been installed and tested with the basic Ref. For cross-compiling, clone the cross-compile tools from here. This demo has configuration files that assume that the tools have been installed in /opt/rpi. If they are installed elsewhere, the location can be updated here.
Crosscompiling using CMake:
The following commands are described at length in the getting started tutorial. These commands will go to the RPI directory and generate a build directory for the RPI example. This step generates a CMake Cache, sets the toolchain use to build the code and does an initial scan of the source tree. Since the RPI example sets a default F´ toolchain file in its CMakeLists.txt, we do not need to supply one on the command line when generating the build. This only needs to be done once to prepare for the build because CMake will detect changes to its files.
cd fprime/RPI
fprime-util generate
The next set of commands will build the RPI code and install it. The installation step is only necessary to make it easier to locate the binary file that the build generates. By default this binary is deep in the build tree and installing it puts the output in the RPI folder under the bin subfolder.
cd fprime/RPI
fprime-util install
After the build has completed, the output binary can be found in the bin/raspberrypi folder. This assumes you build with the default toolchain
of "raspberrypi".
Run the software:
The first step to running the software is to run the ground station. This will allow the code running on the Raspberry PI to downlink telemetry that is then displayed in the user's browser. This next step uses port 50000 for the PI to connect to. The user should ensure that this port is not blocked by the system firewall, and is properly forwarded to the network that the raspberry pi is connected to. In the case of a standard home network where the pi and the user's computer are connected to the same network, these typically do not require special setup.
./scripts/run_rpi_cross.sh
The ground station should now appear in the user's default browser. Should the user wish to terminate the ground system, return to that terminal and press CTRL-C to shut it down. Please allow it a few moments to finalize and exit. The user may then kill the browser tab diaplying the GUI.
In order to run the compiled software, we'll first need to copy it to the RPI. This can be done by creating a new terminal, and running the following commands. Note: the ground station should be left running.
cd fprime/RPI
scp ./bin/raspberrypi/RPI pi@<pi's ip>:
ssh pi@<pi's IP>
Now the binary is available in home directory of the pi user on the raspberry pi and the user has logged into the pi. The user can then run the following command to launch the embedded application:
./RPI -a <ground computer's IP> -p 50000
Switching back to the browser's GUI, the user should see channelized telemetry updating by clicking on the "Channels" tab and events by clicking on the "Events" tab.
Run some commands:
Click on the Commanding tab and drop down the Mnemonic list to see a list of available commands. There are some infrastructure commands, but for the purpose of this demo you can use the Raspberry Pi demo component commands:
| Command | Function | Notes |
|---|---|---|
| RD_SendString | Sends a string on the UART | Loops back to an event if wired. See Log Events tab. |
| RD_SendSpi | Sends a string on the SPI | Loops back to an event if wired. See Log Events tab. |
| RD_SendSpi | Sends a string on the SPI | Loops back to an event if wired. See Log Events tab. |
| RD_SetGpio | Sets a GPIO value | Loops back to GPIO based on the loopback table. |
| RD_GetGpio | Gets a GPIO value | Reads back from GPIO based on the loopback table. The value can be seen in an event in the Log Events tab |
| RD_SetLed | Turns blinking LED on or off | |
| RD_SetLedDivider | Sets LED blink rate. Rate is 10Hz/argument |
Look at channelized telemetry and events.
The telemetry in the system can be seen in the Channels tab. The values update once per second. You can see various values updated by the demonstration component.
Events are asynchronous messages that indicate events have happened in the system. As you exercise the RDcommands, you should see messages appear indicating what is happening in the system.
Use parameters
Parameters are values that are stored on disk for subsequent executions of the software. The demo has one parameter that is used to set the start up state of the LED to blinking or not blinking. To change the value, invoke the RD_PRMLEDINITSTATE_PRM_SET command with the new value. Then invoke RD_PRMLEDINITSTATE_PRM_SAVE to save the value to the RAM value in Svc/PrmDb. Sending the command PRM_SAVE_FILE will then save the value from RAM to disk. The next time you start the software, you can see the new value in operation.
Exit the software
CTRL-C in both terminals will stop the software from running.
Things to look at
The demo consists of a single component along with all the infrastructure components that are part of the repository. The demo component can be found in RPI/RpiDemo. The topology for the demo can be found in RPI/Top. That directory contains the program main() as well as the topology XML (RPITopologyAppAi.xml). You can modify and reuse the demo component, or you can create a whole series of interconnected components to do a project. Developers are encouraged to fork the repo to add functionality to the basic demo to enable whatever projects they have in mind.
Some tips:
- If you would like to add your own components, read the User's manual on how to add new directories to the build.
- If you have defined some component XML, you can generate an empty implementation class by typing
fprime-util impl. - You can see the telemetry and events in
RPI/logs/<date>/channel.logandRPI/logs/<date>/event.logrespectively. - Sometimes you see the error: Could not connect to socket at host addr localhost, port 50000, or address in use This means that the GUI was restarted before the socket was released by Linux. Wait a minute or so and try again.