This device is the first prototype of a localization system for my old camper van. It is based on an Ai-Thinker A7 GPS & GSM module which is communicating over serial with an ESP32 Pico D4. For input & output I have added two buttons and an 0.96" OLED display, but the main idea is that the device can be control by a smartphone App. As you can see in the end of the video I'm using the Blynk 2.0 App which works great for several IoT projects, even for those which are communicating over mobile radio.

All in all the whole project is working fine, but for the next revision I have to optimize two things:
1. The GPS u.fl connector wasn't grounded properly which is a huge drawback in signal strength. Therefore the GPS quality is only acceptable in optimal conditions, even with a good GPS antenna.
2. The power path is not yet optimal. When the device is working a while, the battery looses capacity and cannot deliver enough energy for the power-hungry GSM module. This results in a ESP brownout when data is transmitted/received over mobile radio.

I'm very happy with the result of this project. The transparent solder mask looks beautiful in combination with the acrylic glass cover. There will be a second, probably smaller, version of this thing in the near future, optimize for the use inside my van. Maybe it will be a modular solution which can be stacked onto the VanMeter board - but we will see.