Stefan Wagner's Pocket Radio Features an ATtiny Microcontroller, LiPo Battery, and OLED Panel
Released as open hardware, this clever radio includes a variety of 3D-printed case options to accommodate different speaker depths.
Electronics hobbyist Stefan Wagner has put together a swish-looking pocket radio based on a Microchip ATtiny microcontroller and RDA Microelectronics RDA5807MP chip with a color OLED display β and released it as open hardware, down to its 3D-printed housing.
"PocketRadio is an ATtiny402/412 controlled FM radio with RDS (RDA5807MP), an integrated audio amplifier (TC8871 or XPT8871), a LiPo battery charger (MCP73831 or TP4054), an OLED display (SSD1306), and three buttons," Wagner explains of the compact creation. "You can directly connect a protected 3.7V LiPo battery, a 3W/4Ξ© speaker, and an FM antenna."
The actual radio portion of the build comes courtesy of a RDA5807MP single-chip stereo FM tuner with integrated synthesizer and RDS/RBDS support. "The tuner uses the CMOS process, support[s] multi-interface, and require the least external component[s]," Wagner writes. "All these make it very suitable for portable devices."
Control for the radio chip comes from an ATtiny microcontroller running a custom firmware, with a user interface comprised of a color OLED display and three tactile switches β one to change channels, one to increase the volume, and one to decrease it again. A Microchip MCP73831 battery charge chip provides support for charging a built-in lithium-polymer battery via the radio's USB Type-C connector, with a Microne ME6209 voltage regulator offering low power consumption.
The custom circuit board has a space for a 40mm speaker, which is glued into place and soldered to the board. 3D print files are provided for casings of varying depth, to provide room for particular speaker and battery combinations. "To improve the sound quality, you can pack a foam mat between the battery and the PCB inside the case," Wagner advises. "This should fit snugly against the outer walls of the housing."
Wagner has published the source code and design files for the radio on GitHub under the reciprocal Creative Commons Attribution-ShareAlike 3.0 Unported license.