The Mini-Radio ecosystem continues to mature thanks to ongoing development by H. J. Berndt, whose work on compact digital radio firmware has consistently pushed the limits of what small, SI4735-based receivers can do. The newly released Mini-Radio Firmware V3, available from the official project page, brings meaningful functional upgrades rather than cosmetic changes.
The firmware can be downloaded directly from the developer’s site here:
Mini-Radio Firmware V3 – Official Download
http://www.hjberndt.de/dvb/pocketSI4735DualCoreDecoder.html#download
RTTY and CW decoder
One of the most notable enhancements in this release is the native RTTY and CW decoder, fully implemented within the firmware itself. Developed and optimized by H. J. Berndt, this decoder removes the need for external computers or audio-based decoding software. Morse (CW) and radioteletype (RTTY) signals are decoded internally and displayed directly on the Mini-Radio’s screen, making the receiver far more capable for utility DX, amateur radio monitoring, and experimental listening.
Mini Radio Firmware V3 enhances ATS-Mini DSP receivers with built-in RTTY and CW decoding plus EiBi schedule integration, enabling direct shortwave text decoding and smarter station tuning without external software.
The decoding engine benefits from the dual-core ESP32 architecture, which Berndt’s firmware uses intelligently. Radio control, signal processing, and decoding tasks are handled independently from the user interface, resulting in smooth tuning behavior and stable decoding even on crowded HF bands. Compared to earlier firmware versions, users will immediately notice improved responsiveness during band scans and while viewing the spectrum and waterfall displays.
EiBi integration
Another important addition in Firmware V3 is EiBi integration. EiBi (European Broadcast Information Service) schedules are widely respected among shortwave listeners for their accuracy and regular updates. By incorporating EiBi data into the firmware, the Mini-Radio gains better awareness of active broadcast and utility segments across the HF spectrum. This allows scanning and tuning functions to become more efficient, helping listeners reach active frequencies faster without constantly referring to printed or online schedules.
This integration reflects the practical, listener-focused design philosophy seen throughout Berndt’s work. Instead of turning the Mini-Radio into a complex SDR replacement, Firmware V3 enhances traditional shortwave listening by adding intelligence where it matters most — decoding and frequency awareness.
Importantly, this firmware update does not require new hardware. Existing Mini-Radio builds using supported SI47xx receiver chips can be upgraded directly using the files provided on the developer’s website. Documentation and firmware details are clearly maintained on the same project page, making it accessible even to hobbyists with minimal flashing experience.
Mini-Radio Firmware V3 stands as a strong example of how open, enthusiast-driven development can significantly extend the life and capability of compact radio hardware. With built-in CW and RTTY decoding, EiBi-assisted tuning, and careful optimization by H. J. Berndt, this firmware turns a small portable receiver into a surprisingly capable HF monitoring tool.
CW Decode on Si4732 Mini Receiver
This video demonstrates the real-time CW and RTTY decoding capabilities of the latest firmware on the Si4732 receiver