Dimitris Dimitrakoudis Turns a Junk Drawer Espressif ESP32 Module Into a Hi-Fi Internet Radio

Computer engineer Dimitris Dimitrakoudis has reduced the contents of his junk drawer by one Espressif ESP32-based development board — by turning it into a custom, amplified internet radio streaming gadget.

"A long time ago I bought an ESP32 module off of Ebay. I can't really remember what for, but I did," Dimitrakoudis writes of the device's presence in his spares collection. "So the module arrived a couple of months later, in typical China-to-Greece-by-post fashion. By that time I had literally forgotten what I had bought it for. So it then lay there in a drawer for 4 or 5 years until I randomly came across an article that mentioned that it can output I2S! That was news to me, and obviously interesting."

Finding the ESP32-audioI2S library and confirming that it was capable of retrieving and decoding his favorite internet radio station Dimitrakoudis set about promoting the module from its dust-gathering duties in a project brought to our attention by Adafruit. "I thought that I should do a carrier board for the ESP32," the engineer explains, which would host the previously-unloved microcontroller module while providing a regulated power supply, isolated and buffered I2S output, and boast an on-board digital to analog converter (DAC).

"Since this device would only stream internet radio (a.k.a. 'heavily compressed audio'), the on-board DAC did not have to be anything special," Dimitrakoudis explains. "So let

s go with the all time classic [ESS Technology] ES9023. Let's also do a relatively good power supply for the critical component (DAC chip) but nothing extreme. The rest of the audio-related components can be powered by well respected [Texas Instruments] LP5907 LDOs, while the actual ESP32 can be powered by a run-of-the-mill [TI] LM1117."

The finished carrier board design includes an SD Card slot for local storage, the promised I2S output for connection to an outboard DAC, and the on-board DAC for line-level outputs. A chunky power supply and a front-facing power button finish the build, in an attractive brushed-metal case to match existing audio gear.

"This was a pretty simple and relatively low cost project, an ideal way to keep busy for a couple of winter evenings," Dimitrakoudis concludes. "Also it is a good way to listen to high fidelity internet radio without needing to keep an entire PC and DAC powered up. So it’s good for the environment. It would not be difficult to add an LCD that would display the artist and track that is playing… perhaps sometime in the future."

The full project write-up is available on Dimitrakoudis' website, along with Gerber files for the carrier board under an unspecified license.