Nuvoton W78E054 8051-core microcontroller in a DIP-40 package
47 uF 450V radial electrolytic capacitor with long leads
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PROJECT

=RetroCom=

REV1.0 [WIRED]
LICENCEGPL-3.0

A multiple-channel, two-way simultaneous-speech intercom built around the AT89C52 (8052 core). Four wired stations connected to a main station over CAT6; the main station carries an embedded FM radio module. I wanted to learn how communication systems were built with older electronics, so I built one: firmware, analog audio, boards, case, and documentation.

RetroCom banner
FIG.1 - Project banner. 8052-based intercom system, 2-4 stations wired.

SPECIFICATIONS

MCUAT89C52-PI24 / AT89S52-PU24 (8052 core), one per station
SpeechTwo-way simultaneous - no taking turns, works like a phone call
SwitchingCD4051 & CD4052 ICs on ±5 V rails; preamped signals face no distortion
AudioTL072 preamp stage, LM386 power amp stage
LinkCAT6 carries audio and power; 20-30 m runs OK; no outlets at substations
RadioRDA5807M FM module, main station only (v1.0)
FirmwareC, compiled with SDCC; flash-ready .hex in repo
BoardsKiCad, two-layer, GND fillzone bottom; hand-solder friendly; one SMD part
CaseFusion 360 CAD, assembly drawings in repo
RoadmapWireless HF/UHF variant, 12-100 stations

FIGURES

Main station PCB, 3D view
FIG.2 - Main station PCB, 3D view.
Main station schematic
FIG.3 - Main station schematic.
Case CAD render
FIG.4 - Case, Fusion 360.
Assembled station
FIG.5 - Assembled station, Fusion 360 render.

REPOSITORY

github.com/SamyIOoOI/RetroCom

Inside: KiCad sourcesGerber filesBOM (CSV)Assembly CADCase CAD