I soldered some wires onto the circuit board at pads RX, TX & GND, so that I could use a serial-to-USB cable. As I already discovered, there should be a serial console active. Using Teraterm on Windows, I set the Comm port to 115,200, n, 8, 1. I then set Teraterm to capture everything to a log file. Upon plugging the LTE dongle in, lots of text scrolled down the terminal window. The Linux bootup text is rather lengthy, so I zipped it. Here it is.
There are a few error messages near the start, but the rest of the boot process seems to proceed well. I understand a bit of this, but if someone more knowledgable would like to analyze this and report back, it would be helpful.
Near the end, a login prompt appears,
openstick login:, but the wireless interface isn't finished connecting, so a few more lines scroll by. I hit
[ENTER] and got the login prompt again. After logging in, I ran
halt (I cut out the login text). The remaining text is the output from Linux as it shuts down.
We now know for certain that one serial port is active and being used for a console. Device Tree lists a second serial port as disabled. If we don't mind sacrificing the serial console, we could use the enabled serial port for our own purposes.
The lone TX pad on the top side reads 1.8 VDC. This is the working voltage of the GPIO lines. When brought low, seemingly random characters appear on the serial console with each level transition. Is this TX actually a GPIO input?
I was half right about the two large pads at the top that I thought might be V+ and GND. The GND is ground. I read nothing on the other pad, and it doesn't seem to do anything when brought high or low.
The reason I used
halt, instead of
shutdown is that this dongle reboots when you do a shutdown. doing a halt actually powers the dongle off.
From top to bottom, the LEDs are: Blue, Red, Green.
In the instructions provided by Extrowerk, he says to use
add a wireless connection. Initially, I did this. Later, I found out that you can simply use
activate. You will be presented with a list of WiFi access points found. Select yours, and you will be asked for the password. Enter a password, and wlan0 will connect, and get an IP assigned. You can then SSH into the dongle via your network. This WiFi connection is permanent, unless you use
nmtui to delete it.
To make things easier, you may want to use your WiFi AP to assign a fixed IP to the MAC address of wlan0 on the dongle. That way, the IP will never change.
One other thing I'd like to do is to configure wlan0 as both a client and an AP. I would also like to setup a portal web page, similar to what is done on the ESP32 chips. That way, you could use this dongle on any wireless network, and configure things as needed via WiFi.
I spent some time trying to get some type of remote GUI login working. With
xrdp, I could only get a text console, but it kept disconnecting after a short while. Next, I installed
tightvncserver. I opened port 5901 with
iptables, but the VNC viewer kept telling me that the connection to the dongle was refused. I'm not sure what the problem is. A GUI on the dongle is overkill, but it may be useful for some purposes. I picked jwm because it is one of the least memory intensive window managers. It is used on Puppy Linux and Damn Small Linux.
I need to delve into the intricacies of device trees to see how to enable I2C and SPI, if possible. It would also be nice to be able to reassign the function of those two button pads. It may be possible to use them as generic GPIOs.
I still have more documentation to read. Two people sent me links to even more documentation, so more reading. As usual, anything new will be added to these pages. Feel free to email me with information or constructive comments.