ESP32-CAM as a programmable camera research platform

Experimenting with custom-programming of cameras can be difficult. Most consumer cameras are protected to prevent users from reprogramming them. Industrial cameras can be flexibly controlled by an external computer, but are generally not standalone programmable devices. However, various inexpensive camera modules, designed largely to be used for building IoT (Internet of Things) devices, combine extensive programmability with a camera in a compact, low-power, module. One of the smallest and least expensive, the ESP32-CAM module, combines a 2MP Omnivision OV2640 camera with a dual-core 32-bit processor, 802.11 WiFi and BlueTooth as well as wired I/O interfaces, a microSD slot, low power modes, etc., all supported by the Arduino programming environment and a rich collection of open source libraries. Why not use it for programmable camera research? This paper describes how the ESP32-CAM had to be adapted to enable use in a variety of experimental cameras. For example, some of these cameras do not use the lens screwed and glued onto the OV2640, and replacing this lens revealed a number of issues ranging from spectral response to adjustment of lens corrections. There are numerous strange interactions between different functions that end-up sharing the same I/O pins, so work-arounds were needed. It also was necessary to devise ways to handle various higher-level issues such as implementation of a live view and synchronization across cameras. However, the key problems have been resolved with open source software and hardware designs described here.