Repeater Controller Board and Firmware 

This page introduces the board and firmware for an ESP32-S3-based FM repeater controller.
Download the schematics, PCB design files, KiCad library, and firmware below.
The sections below show the peripheral circuits, PCB fabrication, and board assembly.

 
Schematics, PCB Files, and Firmware Downloads
 Schematics and PCB design files (KiCad format)  Repeater_Controller_PCB_KiCAD_202610011700.zip
 Repeater_Controller_PCB_KiCAD_202610261500.zip
 Downloads: —
 KiCad library  KiCad_Library_ver4.zip Downloads: —
 Repeater controller firmware  FM_rep_ESP32-S3_Wifi_vox_Ver0.1.0.zip
 FM_rep_ESP32-S3_Wifi_vox_Ver0.1.1.zip		 Downloads: —




 Sales Information
 Bare PCB  US$20.00
 Partially assembled board for integration (without LCD panel)  US$70.00
 Fully assembled board  US$80.00
 Complete unit  US$126.67

For shipping costs, please contact us at the email address below.
du9@ji1fgx.com
 ESP32-S3 and Peripheral Circuit Schematics
 ESP32-S3  Controller microcontroller
 ILI9341  2.4-inch LCD with touch panel
 DFPlayer  MP3 player used for voice ID announcements
 DS3231  Real-time clock (RTC): TEFUK Essential DS3231 RTC Time Module



Analog Audio Mixer Circuit

This circuit combines receiver audio, CW tones generated by the ESP32-S3, and voice ID audio from the DFPlayer, and feeds the combined signal to the transmitter microphone input.
Receiver audio is coupled through a 600-ohm to 600-ohm audio transformer. The receiver audio, CW tone, and voice ID levels can each be adjusted using their respective potentiometers.
A portion of the receiver audio is also routed through level adjustment and protection circuitry to the audio input used for software DTMF decoding.
 PCB designed in KiCad
PCB manufactured by JLCPCB
Assembled board
The analog audio mixer is on the left, the ESP32-S3 is on the right, and the RTC and DFPlayer are at the bottom.

VOX (voice-operated transmit control) was initially implemented using an op-amp circuit.
Because the circuit frequently triggered incorrectly, VOX was changed to a software implementation.
DTMF (touch-tone) decoding is also performed in software.

Board Adjustments, Connectors, and Main Components
ReferenceDescription / Function
VR1Main rig AF volume
VR2CW TONE
VR3AF input level to the radio
VR4Voice ID level
VR5VOX / DTMF input level
J1RTC (DS3231) connector
J2SQL input from the radio
J3+3 V power connector (unused)
J4AF input from the radio
J5MIC / PTT connections to the radio
J6TX / RX LED connector
J7LCD panel connector
U1 / U2PC817 optocouplers
U3ESP32-S3
U4DFPlayer
Board Modification for Repeater Controller Ver0.3

The Ver0.3 board requires one jumper wire.
Connect a jumper wire from the cathode of diode D3 to pin 1 of the RTC connector J1.

This issue has been corrected in the Repeater Controller Ver0.4 board.