HowTo – Pair – NextGen Astromech

Why Paring?

“Paring” of modules is necessary to establish wireless communication via ESP-NOW. To avoid external interventions or even highjacking your controls, each module has to have knowledge about it’s communication partners. Stating the Espressif website, ESP-NOW is a “protocol developed by Espressif, which enables multiple devices to communicate with one another without using Wi-Fi. The protocol is similar to the low-power 2.4GHz wireless connectivity (…) . The pairing between devices is needed prior to their communication. After the pairing is done, the connection is safe and peer-to-peer, with no handshake being required.”

After pairing a module with each other, the connection is persistent. In other words, if suddenly one of your modules loses power or resets, when it restarts, it will automatically connect to its peer to continue the communication.

Although it is possible for the individual modules to communicate with each other, this option is not useful in most cases. Main communications is between the “brain”/shield in the body and each other module.

When using “automatic pairing” each module knows about the partners that are relevant and will store the MAC addresses. When using “manual paring” it is necessary, that the user has knowledge about the way the AstroCAN is designed to work.

Automatic Pairing

All AstroCAN modules have to be connected via CAN-bus. All AstroCAN modules have to be powered up. There are two ways how to pair:

Option: press an hold the “boot” button on one of the modules for at least 3 seconds. All active modules will be paired now.
Option: connect via serial monitor to one of the modules. Enter “/PAIR”. All active modules will be paired now.

Manual Pairing

All AstroCAN-Modules have unique MAC addresses. These are used to establish an authenticated wireless communication via ESP-NOW. To establish manual pairing, perform the following steps:

Connect your AstroCAN-Modul via USB to your computer
Start a serial monitor to connect to your module. Connection settings 115200 Baud, 8N1
Enter /SETTINGS in your serial monitor
Your will see a bunch of module specific settings. First one is the MAC-Address:

--Settings--
MAC: 0C:B8:15:CD:6E:7C

Make a note of the MAC address and the module name (e.g. “Dome Bridge – 0C:B8:15:CD:6E:7C”).

Repeat for each module. The MAC is permanent, so you just have to do this once for each module.

As soon as you have all your module MAC addresses start pairing. When pairing a Mega Shield with the dome bridge do the following steps:

Connect your AstroCAN-Shield via USB to your computer
Start a serial monitor to connect to your module. Connection settings 115200 Baud, 8N1
Enter /HELP in your serial monitor to ensure, the connection is up and working
Enter /SETDOME to pair the shield with the bridge, in our example /SETDOME 0C:B8:15:CD:6E:7C
Enter /RESTART
Now connect your AstroCAN-Bridge via USB to your computer
Start a serial monitor to connect to your module. Connection settings 115200 Baud, 8N1
Enter /HELP in your serial monitor to ensure, the connection is up and working
Enter /SETBODY to pair the bridge with the shield
Enter /RESTART

Now both modules know of each other and are ready to communicate wireless. Repeat these steps with all the modules, that have to communicate to each other.

You like the automatic pairing better? So do I 😉

Check Pairing

tbd