First experiment with board running an embedded Linux
Learn how to run an experiment and interact with boards running an embedded Linux using the command line interface (CLI tools).
Access to the SSH frontend
The SSH frontend has all the tools and compilation toolchains already installed. They are also the place from where you can interact with the nodes.
You need to Configure your SSH Access if it’s not already done.
Let’s connect to the SSH frontend to use the CLI tools from there, by replacing <login> with your IoT-LAB login:
ssh <login>@grenoble.iot-lab.info
If you never used the CLI tools from this SSH frontend, you need to store your credentials with the following command:
iotlab-auth -u <login>
Thus, you won’t need to specify your login and password at each call to CLI tools.
Submit the experiment
The board you will use here has a co-microcontroller, providing sensing and communication features. First, download the firmware you will use later for this co-microcontroller in your ~/shared directory:
wget https://iot-lab.github.io/assets/firmwares/tutorial_a8_m3.elf -P shared
Then, submit a 20-minutes experiment, named first-exp, using 2 IoT-LAB A8-M3 boards (m3:at86rf231) from the grenoble site:
iotlab-experiment submit -n first-exp -d 20 -l 2,archi=a8:at86rf231+site=grenoble
Wait until the experiment’s state is Running
iotlab-experiment wait
Connect to the embedded Linux system
Get the nodes list assigned to your experiment by the scheduler:
iotlab-experiment get -n
{
"items": [
{
"archi": "a8:at86rf231",
"camera": null,
"mobile": "0",
"mobility_type": " ",
"network_address": "a8-101.grenoble.iot-lab.info",
"production": "YES",
"site": "grenoble",
"state": "Alive",
"uid": "2587",
"x": "19.75",
"y": "4.50",
"z": "2.63"
},
{
"archi": "a8:at86rf231",
"camera": null,
"mobile": "0",
"mobility_type": " ",
"network_address": "a8-100.grenoble.iot-lab.info",
"production": "YES",
"site": "grenoble",
"state": "Alive",
"uid": "3185",
"x": "19.75",
"y": "3.90",
"z": "2.63"
}
]
}
Here, the experiment is running with the a8-100 and the a8-101 nodes in Grenoble.
Embedded Linux boards need between 30 seconds and 2 minutes to boot, depending on the testbed activity. Once it’s done, they are accessible with a root access through SSH. The hostname to use is the node id prefixed by node-.
ssh root@node-a8-<id1>
From this minimal embedded Linux system, most unix commands are supported. For example you can test the network connectivity between your two boards:
ping node-a8-<id2>
Flash the co-microcontroller
The ~/shared directory in which you downloaded the firmware previously is automatically mounted by NFS in the embedded Linux environment. Thus, you have an easy access to the firmware.
Use the iotlab_flash script that interfaces with Open On-Chip Debugger (OpenOCD) to flash it:
iotlab_flash ~/shared/tutorial_a8_m3.elf
You can also find iotlab_reset script to reset the M3 co-microcontroller.
Interact with the co-microcontroller
The co-microcontroller serial port link (i.e. UART) is available under /dev/ttyA8_M3. You can use the pySerial console application to access to it, using a baudrate speed of 500 kB/s:
miniterm.py --echo /dev/ttyA8_M3 500000
The firmware is waiting for reading characters to its serial link to do respectives actions.
Here is its help:
IoT-LAB Simple Demo program
Type command
h: print this help
t: temperature measure
l: luminosity measure
p: pressure measure
u: print node uid
d: read current date using control_node
s: send a radio packet
b: send a big radio packet
e: toggle leds blinking
cmd>
Test some actions by typing the corresponding character then Enter.
If you want to see reception of radio packet by the second node, open a second terminal, and run this set of commands:
ssh <login>@grenoble.iot-lab.info
ssh root@node-a8-<id2>
miniterm.py --echo /dev/ttyA8_M3 500000
Go Further
- Learn how to interact remotely with embedded Linux boards and automate actions such as waiting for the end of the boot or flashing a firmware on the co-microcontroller by reading the SSH-CLI documentation.