Markus Opitz's Tiny Camera Takes a Brute-Force Approach to Power Saving
Providing power only while the shutter button is held down means this ultra-compact camera has zero "vampiric" power draw.
Self-described artist, maker, and teacher Markus Opitz has built an ultra-compact portable camera β designed to save energy by only firing up its Espressif ESP32-S3 microcontroller when you actually press the button to take a photo.
"Amazingly tiny outdoor photo cam for quick one-handed use," Opitz writes of his creation. "This camera is lightweight (26g), cheap and can be operated with just one hand. It is for photos only, not for videos! [You] hold the device steady and keep the button pressed. During image capture and storage the LED is on. Keep button pressed until the LED goes out again (-3 sec), then the saving process is complete."
The heart of the project, hidden away inside a 3D-printed housing which looks like a pocket camera that shrunk in the wash, is a Seeed Studio XIAO ESP32-S3 Sense β built around the Espressif ESP32-S3 microcontroller and boasting integrated battery management and an on-board Ominvision OV2640 camera module. While it also includes 2.4GHz Wi-Fi and Bluetooth 5 Low Energy (BLE) connectivity, they're not in use in Opitz's project.
Opitz's approach to maximizing battery life is simple indeed: the camera's shutter button is actually wired between the microcontroller and the project's lithium-polymer battery. By holding it down, the microcontroller is powered and booted β at which point it lights an LED and captures an image, writing it to a microSD Card loaded into its on-board reader. When the LED goes out, the writing has finished and you can release the button.
It's a brute-force method of power management which ensures absolutely zero "vampiric" drain from the battery while the camera isn't in use β but that comes at a cost: if you let go of the shutter button before the LED goes out, your photo will almost certainly be corrupted.
"In several tests I could make about 120 pictures (720Γ420 px) with one battery charge," Opitz says of the camera's performance. "It is as exciting as it used to be in the good old pre-digital age: you didn't have a display then and you had to wait until the pictures were developed. Yes, and some pictures are not [β¦] good either β like in the past!"
The full project write-up is available on Opitz's Instructables page.