Hi, just got an LGT-92 through Antratek. Looks like a very nice, robust and inexpensive, tracker.
After activating it, I immediately got a “hit” to a gateway approximately 2.5 km away (lot of buildings in between). With other devices/kits it’s not always that I reach that gateway the first time around. So at least something was done right with the antenna circuit.
I bought this one because it has open source firmware and the hardware is well documented.
The firmware programming interface seems a bit awkward, with the not-quite-USB cable, but I guess it works. I have some previous experience with STM32F103 microcontrollers (“blue pill”) and those allow you to put an USB bootloader them. The USB bootloader makes it easy and very fast to upgrade the firmware over USB and also provides an USB serial port to your arduino sketch. Seems like a bit of a missed opportunity that this device is not using that mechanism (easier said than done).
On the other hand, this is a different microcontroller. It appears to be the same microcontroller as present in the RAK7200 tracker.
My plan is to be able to create my own firmware, get things like a Cayenne payload in it, also include the HDOP (or number of satellites). Perhaps try if I can get an USB bootloader on it anyway.
The MCU should already have USB DFU capability in the factory boot ROM - it’s just the early ST USB-enabled parts like the '103 which have to have it added after.
But that’s pretty much irrelevant as the board doesn’t actually have a USB port. What it has is a USB connector misused for power and SWD.
There’s no support for USB communication on that connector, and the MCU’s USB pins seem dedicated to other purposes.
There are a lot of possibilities to configure in the software. It is a bit awkward to configure as a tracker (besides the odd serial interface). AT-commands sometimes just fail and you have to type them in again until they succeed.
I think there are a couple of bugs, or perhaps I don’t quite understand some things, they are not explained in the manual:
The data rate setting doesn’t appear to “stick”. I configured the tracker as ABP and set the datarate to 5 (AT+DR=5). But after a reset (ATZ), the device responds with a setting of 0 again (AT+DR=? -> 0).
I’ve seen some issues with the device not honoring the transmit interval setting (AT+TDC)
Setting the device address requires spaces in the address, like 26 01 1A 30, yet it is reported without spaces (AT+DADDR=? or AT+CFG).
The session keys also require spaces, so you can’t just copy / paste them from the TTN console.