How to use device tree overlays

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Using the WiFi FeatherWing on the Giant Board

The Giant Board uses u-boot overlays to load the device configurations at boot. This makes it easy to enable and disable hardware being used with Linux drivers instead of CircuitPython.

The easiest way to change the overlay options its to edit the uEnv.txt text file using this command 

sudo nano /boot/uboot/uEnv.txt

When the file opens, it should look like this

Make sure to uncomment the line enable_uboot_overlays=1 this allows overlays to load on boot: 

# enable u-boot overlays
enable_uboot_overlays=1

You’ll then want to add the line /overlays/GB-WIFI-FEATHERWING.dtbo to the first dtboverlay variable. Which should look like the image below.

After completing the steps above, we can now go over how to connect to a WiFi network using connman, which is pre-installed.

Once the reboot is complete, proceed to login and then type the command: 

sudo connmanctl

You should see a connman command prompt and then you can type the following commands:

enable wifi

then wait for the response"Enabled wifi"

scan wifi

you should see the response"Scan completed for wifi" when the scan has completed.

In the next step you’ll want to type:

services

There should be a list of nearby WiFi connections displayed after. You then want to copy the wifi_*_managed_psk of the network you want to connect to.

In the next step we want to enable the connection agent by typing the command:

agent on

Which should follow up with the response "Agent registered“

From here we can connect to the WiFi connection you copied earlier:

connect wifi_*_managed_psk

If everything connected properly, you should see the response “Connected wifi_*_managed_psk”. After you see this message, you should be connected to WiFi and it should connect automatically at reboot. We can now type “quit” in the command prompt to return to the normal terminal.

To verify if you are connected to the internet you can type:

ping -c 4 8.8.8.8

You should see a response back if everything is setup properly.

If you are experiencing random shutdowns when enabling or connecting to WiFi, you may need to connect a battery to the Giant Board. The Giant Board and the WiFi FeatherWing operate very close to the 450mA limit set while being powered over USB. Connecting a battery eliminates this issue and increases the limit.