Let's talk about each problem in a little more detail and summarize the requirements

What if the analog device is in a place with no stable Wi-Fi?

Aside from the obvious reason-'Wi-Fi signal is too weak'-the Wi-Fi channels can be crowded with other devices, so the ESP32 may disconnect after some time. Luckily, the ESP32 also supports Ethernet connectivity, which I personally use whenever possible. Unfortunately, the classic ESP32-Cam doesn't support Ethernet. So the first requirement for the AI-on-the-Edge-Cam board was to ensure Ethernet support.

What if there's no network access at all?

Sometimes it's impossible to get any network connection. In such cases, you need to use alternative long-range communication protocols like LoRaWAN. With LoRaWAN, you can place the gateway several kilometers away from the device and still get the data. In fact, this is where Edge computing really shines. LoRaWAN has limitations on the amount of data you can transfer, so for example you can't easily send pictures over LoRaWAN. (Of course, you could split the image into multiple packets, but I won’t cover that kind of dark sorcery here.) Luckily, the Ai-On-The-Edge-Device  processes everything on the edge (on the ESP32) and outputs only a few bytes of data that can easily be sent to your server via LoRaWAN. Unfortunately, the ESP32-Cam doesn't have enough pins to drive standard SPI LoRaWAN modules (unless you replace the SD card, but the Ai-On-The-Edge-Device  framework requires an SD card). So requirement number two is 'LoRaWAN compatibility'.

What if there isn’t even a reliable power supply?

Let's cover this topic in relation to our previous scenarios:

1. If Ethernet is available
One cool thing about Ethernet is that you can power the device via the Ethernet cable using PoE, which also reduces the amount of wiring (only one Ethernet cable instead of both Ethernet + power cables). So PoE is another requirement.
2. If Ethernet is not available
If the meter is in an area with no power and no Ethernet connectivity, one option is to use a battery. So battery management is another nice-to-have feature. The downside of batteries is that they eventually discharge, and the ESP32 tends to consume a lot of power while running. The ESP32-Cam also can't disconnect the camera or SD card before going to sleep, which is necessary to achieve the lowest possible power consumption

What else is good to have and why?

Ai-On-The-Edge-Device framework itself requires SD card and OV2640/OV5640 Camera connector.

It also allows smart led driving for setting up the lighting, so let's put 4xSmart LEDs directly on the board, but allow users to connect external leds if needed

There is no reason to drop Wi-Fi functionality. Regarding antennas, there are two ESP32 module types: one with a PCB antenna and one with an external antenna connector. The external connector is preferred by me, as it allows the user to optimize the final solution either for size or for reception strength, depending on environmental conditions.

Ov2640 camera uses I2C, so why break it out on some I2C connector. The commonly used I2C connector standards I'am aware of are Stemma QT/QwiiC, Stemma and Grove. Stemma QT/Qwiic is the smallest one.

Requirements list

• Ethernet support - stable connectivity when Wi-Fi is unreliable.
• LoRaWAN compatibility - long-range data transfer when no traditional network is available.
• Power over Ethernet (PoE) - power the device through the Ethernet cable.
• Battery management, measurement and ultra-low-power sleep - for off-grid scenarios; ability to shut down camera/SD before sleep.
• SD card connector - for loading and saving configuration and images.
• OV2640/OV5640 Camera connector. - Both cameras have the same pinout
• 4xSmart LEDs - For stable lighting control in dark environment
• Status LED -  Ai-On-The-Edge-Device framework utilizes it pretty heavily, so let's have it too.
• External antenna connector for WiFi...