1. Schematic and Board Layout
  2. Boot Loader and Firmware
  3. Repeater Builder Web Pages
  4. OpAmp in TX and RX chains
  5. SWD - Serial Wire Debug
  6. Powering the Rpi and DVM via the DVM board
  7. Installing an oled Display
  8. Installing a Nextion dispay

Related Pages:
  1. Any-Tone-AT-D868/Anytone-AT-D868.html
  2. MMDVM_HS_Dual_Hat_Duplex
  3. Radioddity OpenGD77
  4. MMDVM-Mutli-Mode-Digital-Voice-Modem
  5. Digital-Modes/Pi-Star/Pi-Star.html
  6. Digital Mobile Radio (DMR)


Official Product of Scott Zimmerman / Repeater Builder
Inspired from a similar design: github.com/wojciechk8/MMDVM_pog
Low-pass filter design by SQ6POG
Images property of Repeater Builder.
Logo Design by Elisha Zimmerman KB9WCX
HTML June 17, 2017 - N3XCC


Schematic and Board Layout

There are two chains of low-pass filtering. (One for TX, one for RX) These filters are a 3 pole filter with a "knee" of approximately 4kHz. There is a 25 turn potentiometers for fine Receive and Transmit Audio level adjustment. and a DB-9 connection to the host repeater. RSSI support built on-board, as well as 'clip' circuit to help with RX level adjustment.

Link to the Version 3a (Blue) Schematic and Board Layout of the STM32-DVM.(local)

Link to the Version 4 (Black) Schematic and Board Layout of the STM32-DVM.(local)


Boot Loader and Firmware

Link to the Bootloader Instructions to reload firmware. (local)


Repeater Builder Web Pages

For more information on the STM32-DVM see: http://www.repeater-builder.com/products/stm32-dvm.html

Note: The pre-loaded software is freely downloadable from - https://www.pistar.uk/.


OpAmp in TX and RX chains

MCP6002 - 1 MHz, Low-Power Op Amp:


The FT230X is a USB to serial UART interface with optimised pin count for smaller PCB designs.



SWD - Serial Wire Debug

ARM's Serial Wire Debug (SWD) replaces the traditional 5-pin JTAG debug interface by introducing a 2-pin interface with a clock (SWDCLK) and a single bi-directional data pin (SWDIO), providing all the normal JTAG debug and test functionality, anyhow dayisy-chaining devices as via JTAG is not possible. SWDIO and SWCLK are overlaid on the TMS and TCK pins, allowing to use the same connector for JTAG and SWD. In order to communicate with a device via SWD, data is send on SWDIO, synchronous to the SWCLK. With every rising edge of SWCLK, one bit of data is transmitted or received on the SWDIO pin.

Jumper J3 has six pin for the Serial Wire Debug connector



Powering the Rpi and DVM via the DVM board


Installing an oled Display

There are two variants of the SSD1306 display, one running on SPI bus and the other on I2C. f5uii discrible how to install the i2c variant.



Installing a Nextion dispay

Probably the easiest way t do the is using a USB to Serial Converter. See link below.


Glenn Lyons VK4PK
Ver:gnl20181103 - pre published v0.9