This Espressif ESP32-Powered 4G "Smartphone," Programmed in the Arduino IDE, Packs The Essentials

Pseudonymous maker "LuckyBor" has decided off-the-shelf smartphones are a little too bloated — so built a DIY version with 4G cellular connectivity, voice call, text messaging, data connectivity, and even camera support.

"It's an [Espressif] ESP32-S3 N16R8, a 4G A7682E SIMCom modem, and it can make calls, and send texts," LuckyBor writes of the project, which perhaps stretches the definition of "smartphone" a little — but easily passes as a usable featurephone. "It has a 2MP [Omnivision] OV2640 camera, and a 3,000mAh battery, it also has a 3.5” 480×320 touchscreen, and a headphone jack with a buzzer for notifications!"

The microcontroller at the heart of the build is programmed using the Arduino IDE, and ticks the main boxes of what you'd need from a phone: voice calls and text messaging, plus data connectivity for general-purpose apps, over a 4G cellular connection — the latter being a key feature, with many DIY phone projects having been built around 3G connections being turned off in many countries or the even older 2G standard.

LuckyBor's current build is described as a proof-of-concept prototype, and while it can make calls, send messages, and snap pictures, it's a little awkward for general-purpose use. "This is just a basic prototype that's very thick," the maker admits, "and not really ready for [use as] a phone (FYI you have to remove the display to put in a SIM card)."

The planned final version of the phone will, LuckyBor says, include microSD Card storage — and with it the ability to run a port of id Software's seminal first-person shooter Doom, because of course a smartphone needs to run Doom — and a custom PCB that will switch from the European-exclusive SIMCom A7682E to the global A7670G.

More information is available in LuckyBor's Reddit post; the maker has pledged to release the design and source code on GitHub "when I finish [the design]."