ZUM Radio MMDVM-Pi User manual

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 1 Rev 1.0
MMDVM-Pi rev. 1.0 board
The MMDVM-Pi hardware radio interface is part of the Multi-Mode Digital Voice Modem open source
project. It combines the power of an ARM processor and analog radio interface to create a modem to
handle all amateur digital voice modes.

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 2 Rev 1.0
Table of Contents
Specifications ................................................................................................................................................3
Wiring connections.......................................................................................................................................3
Adjusting signal levels (hardware)................................................................................................................4
Adding an external display............................................................................................................................6
Configuring Pi-Star (including adjusting signal levels via software) .............................................................8
Building MMDVM-Pi firmware....................................................................................................................11
On Windows 10.......................................................................................................................................11
On Ubuntu...............................................................................................................................................12
On macOS................................................................................................................................................12
On Pi-Star................................................................................................................................................13
Flashing MMDVM-Pi ...................................................................................................................................15
Windows .................................................................................................................................................15
Linux and macOS.....................................................................................................................................18
Pi-Star......................................................................................................................................................19
Find IP Address............................................................................................................................................20
Info for use under Windows 10 ..................................................................................................................21
Support .......................................................................................................................................................21

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 3 Rev 1.0
Specifications
The MMDVM-Pi board is designed for repeater and high power hotspot applications –connects to user
supplied Raspberry Pi board and radio(s)
Utilizes a high performance 32bit ARM processor (STM32F722) running at 180Mhz (Room for
future upgrades)
Fifth generation analog filter design that provides an extremely low BER compared to previous
generations
2 Multi-turn pots for fine RX and TX adjustments
Onboard LEDs to show status and modes (PTT, COS, Power, D-Star, DMR, P25, Fusion, NXDN and
POCSAG)
Onboard LED to show receive signal level clipping
Connection for OLED and Nextion LCD screens
8 pin JST Connector with pigtail wires
Open source MMDVM firmware preloaded and easily upgraded by software
Wiring connections
Here is a picture of the 8 pin header with cable showing wire colors:
Here is a table of the pin numbers, names and wire colors:
Pin number
Signal name
Description
Wire color
1
CTRL
Control (output)
Black
2
COS/STAT1
Carrier sense (input)
Red
3
RX audio
Receive audio from radio (input)
White
4
Ground
Signal ground
Yellow
5
Ground
Signal ground
Orange
6
TX audio
Transmit audio to radio (output)
Green
7
PTT
Push to talk (enable transmit) (input)
Blue
8
RSSI
Received signal strength indicator (input)
Purple

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 4 Rev 1.0
Here’s an example radio’s (FT-7900) pin connection via the mini DIN 6 connector on the rear of the
radio:
Pin number
Signal name
Wire color
Mini DIN 6 connector
3
RX audio
White
9600 from radio
4
Signal ground
Yellow
GND
6
TX audio
Green
Audio to radio
7
PTT
Blue
PTT
Adjusting signal levels (hardware)
Here is a picture of the test points on the PCB that can be used to look at the RX and TX signal levels on
an oscilloscope. The signal on JP7 is the RX signal audio on the ADC input pin of the STM32 chip. JP6 has
the TX signal audio on the pin going to the radio.

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 5 Rev 1.0
Here are some signal images captured on an Oscilloscope
RX-(JP7) TX-(JP6)
Noise without signal (JP7)
JUMPER DESCRIPTION TABLE
Bypass Pad
ON
OFF
Description
J1
X
Disable DC blocking capacitor on Radio RX end
J1
X
Enable DC blocking capacitor on Radio RX end
J2
X
Bypass 10K variable resistor
J2
X
Enable 10K variable resistor
J7
X
Disable DC blocking capacitor on Radio TX end
J7
X
Enable DC blocking capacitor on Radio TX end
LED Description Table
LED NAME
Description
PTT
Board is transmitting
COS
Board is receiving
STAT
Status
NXDN
NXDN Enabled
POCSAG
POCSAG Enabled
D*
D-Star Enabled
DMR
DMR Enabled
P25
P25 Enabled
YSF
YSF Enabled
PWR
Board is receiving power

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 6 Rev 1.0
Adding an external display
JP8 is where you can solder a header for connecting an OLED display. JP10 is where you can solder a
header for connecting a NEXTION display.
For connecting a NEXTION display, make sure that each colored wire matches the connections shown in
the image below.

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 7 Rev 1.0
Here is a picture of the two trim pots used to adjust the signal levels of the RX and TX audio
Turning the RX audio trim pot counter-clockwise will increase the signal level, while turning the trim pot
clockwise will decrease the signal level.
Turning the TX audio trim pot counter clockwise will decrease the signal level, while turning the trim pot
clockwise will increase the signal level.
When there is no audio stream coming in, adjust the RX pot until the RX CLIP LED barely lights up.

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 8 Rev 1.0
Configuring Pi-Star (including adjusting signal levels via software)
From the “Configuration” menu, set the Radio/Modem type to “ZUM Radio-MMDVM for Pi (GPIO) and
then select Apply Changes.
Next select the “expert” menu, and then select “MMDVMHost”

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 9 Rev 1.0
Scroll down to the “Modem” section to access the invert and level settings then select “Apply Changes”
Scroll back up to the top of the page and select “Configuration”.

Elite 3.5 LCD ZUMspot kit user guide
Copyright 2019-2022 ZUM Radio, Inc 10 Rev 1.0
Next, select “Power”
Next, select “Reboot”