ICS PI-REPEATER-2X User manual

WWW.ICS-CTRL.COM USER MANUAL FOR HARDWARE REV 3.11 07-APR-2018
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PI-REPEATER-2X
HARDWARE REVISION 3.1
1. WELCOME
Thank you for purchasing the PI-REPEATER-2X, the first
repeater controller board designed to be powered by the
ubiquitous Raspberry Pi computer systems.
This little piece of hardware mates to the Raspberry Pi just
like any other daughter card you may have used for the
Raspberry Pi, Arduino, or other development platform.
This system enables you to have a variety of control options
for your station, including simplex, duplex, 2 independent
repeaters, a voting station, etc. Anything you can imagine
that can be done with 2 receive radios and 2 transmit radios
is possible.
We use multiturn potentiometers for fine adjustment of the
audio, offer hardware pre-emphasis filtering, active high /
active low selects for each COS / CTCSS input signal, and
have inputs tolerant to 18Vdc for the signals coming from
the radio.
This board will work with any software that is capable of
interacting with the sound card, and GPIO (I2C required)) for radio interfaces. We recommend getting
started with SVXlink, but the choice is ultimately yours! Feel free to experiment and decide which
system best fits your requirements.

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2. CONTENTS
1. Welcome ......................................................................................................................................... 1
2. Contents ......................................................................................................................................... 2
3. Hardware Introduction .................................................................................................................... 3
3.1 Independent Repeater Channels ................................................................................................. 4
3.1.1 Repeater Channel 1 .................................................................................................................. 4
3.1.2 Repeater Channel 2 ................................................................................................................. 5
3.1.3 Input Audio Adjust ................................................................................................................... 5
3.1.4 Flat audio select ....................................................................................................................... 6
3.1.5 Output Audio Adjust ................................................................................................................ 6
3.1.6 CTCSS Active High/Low ........................................................................................................... 6
3.1.7 Port Connector & Pin 1 ............................................................................................................ 7
3.2 Output amplifier gain .................................................................................................................. 7
3.3 Built-in Audio .............................................................................................................................. 7
3.4 Analog to Digital Converter ......................................................................................................... 8
3.5 GPIO Expansion ........................................................................................................................... 8
3.6 GPS OPTION ............................................................................................................................... 9
3.7 I2C Expansion .............................................................................................................................. 9
3.8 SPI Expansion ............................................................................................................................ 10
3.9 I2S Expansion ............................................................................................................................ 10
3.10 1-WIRE Header .......................................................................................................................... 10
3.11 UART Header ............................................................................................................................ 11
3.12 PI Stacking Header .................................................................................................................... 11
4 Getting Started with svxlink .......................................................................................................... 12
4.1 Hardware Pin numbers (SVXlink based) .................................................................................... 12
4.2 Advanced Configurations .......................................................................................................... 12
5 Schematic ..................................................................................................................................... 13

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3. HARDWARE INTRODUCTION
There are many features built into this little board that you
should be aware of as they can easily be missed when setting
up the hardware for the first time. Your software selection
may or may not support all the features right out of the gate.
This board contains the following features which will be
discussed in more detail in the following sections
 2 independent repeater channels
o Selectable High/Low COS/COR
o Selectable High/Low CTCSS
o Selectable Flat Audio
o Adjustable audio input level
o Adjustable audio output level
 Built in audio (input/output)
 Analog to Digital Converter
 GPIO expansion
 GPS (Optional expansion)
 I2C Expansion Header
 SPI Expansion Header
 I2S Expansion Header
 1-Wire Header
 UART Header (shared with GPS)
 PI Stacking Header
GPIO
PORT 2
PORT 1
ADC
I2C
SPI
UART
Stacking
Header
GPS PORT 2

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3.1 INDEPENDENT REPEATER CHANNELS
The board supports 2 independent repeater channels, or ports 1 and 2. Each channel provides several
helpful features
 Selectable High/Low COS/COR
o Select the switch setting as shown in the following sections to select the polarity of
active signaling for your radio (typically active low)
 Selectable High/Low CTCSS
o Select the switch setting as shown in the following sections to select the polarity of
active signaling for your radio (typically active low)
 Selectable Flat Audio
 Adjustable audio input level
 Adjustable audio output level
 Optional Pull-up circuit for PTT
o (for active high rigs, not installed by default, contact us if you need this functionality)
3.1.1 REPEATER CHANNEL 1
FLAT AUDIO SELECT
CTCSS HI <-> LOW
PORT 1
Interface
Input AUDIO Adjust
Output AUDIO Adjust
Output Amplifier Gain
COS
LOW
<
-
>
HI
PIN 1

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3.1.2 REPEATER CHANNEL 2
3.1.3 INPUT AUDIO ADJUST
The input audio adjust is used to adjust the amplitude of the volume coming from the receiver, with
clockwise rotation turning the amplitude down <needs confirmed>. This is an 18 turn, 10kΩ
potentiometer, multiple turns are required to effect a large change in amplitude, while fractional turns
yield fine resolution adjustments.
The input audio should be approximately <TBD> volts peak to peak as measured at Q1/Q2 (Bottom left
corner near mounting hole) as applicable for the channel being measure.
Input AUDIO Adjust
FLAT AUDIO SELECT
CTCSS HI <-> LOW
PORT 2
Interface
PIN 1
Output AUDIO Adjust
Output Amplifier Gain
COS
HI <-> LOW

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3.1.4 FLAT AUDIO SELECT
This is use to select if the audio coming in requires the addition of a flat-audio filter (removes pre-
emphasis). To enable the addition of the flat audio filtering, the switches should be in the down
position (towards the USB/ETH jacks on the PI).
To pass the audio unfiltered, the switches should be in the up position as shown in the figures above.
To learn more about “Flat Audio” we recommend starting here:
http://www.repeater-builder.com/tech-info/flat-audio.html
3.1.5 OUTPUT AUDIO ADJUST
The output audio adjust is used to adjust the amplitude of the volume coming from the repeater board.
This is an multi turn, 10kΩ potentiometer, multiple turns are required to effect a large change in
amplitude, while fractional turns yield fine resolution adjustments.
This function is used to adjust the amplitude of the repeated audio being sent to your transmitter radio.
This output amplitude should be adjusted per the transmitter radio specifications.
3.1.6 CTCSS ACTIVE HIGH/LOW
This switch is used to select the active on state for the CTCSS signal from the receiver radio. Typically
this will be active low, but some radios output an active high signal.
When using active high signaling, the input will trigger above 1.25V and will release when the signal
returns below 0.6V.
When using active low signaling, the input will trigger below 0.4V and will release when the signal
returns above 0.7V
3.1.7 COS ACTIVE HIGH/LOW
This switch is used to select the active on state for the COS signal from the receiver radio. Typically this
will be active low, but some radios output an active high signal. This input can be used for 3-18Vdc
signal levels.

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3.1.8 PORT CONNECTOR & PIN 1
Each repeater port comes out to a 2x5 male header. This header is typically connected 1:1 into a DB9
Female connector, but the user may also make a custom cable/adaptor for their own equipment if
desired.
Connector Selection: Due to the tight spacing of the board, it is important to select mating connectors
that do not exceed the width of the male pin alignment blocks, or you risk mechanical interference with
the port 2 header. For custom cables we suggest using connector block 952-2033-ND from Digikey, or a
similar variant. STANDARD IDC RIBBON CABLE CONNECTORS WILL NOT FIT.
Pin 1 is located in the bottom left corner as shown above in section 3.1. When using ICS-CTRL provided
DB9 connectors, will correspond with the brown wire.
CONNECTOR PINOUT:
1- CTCSS ENCODE OUTPUT
2- CTCSS INPUT FROM RX RADIO
3- PUSH TO TALK (OPEN COLLECTOR)
4- AUDIO OUTPUT
5- AUDIO INPUT
6- GROUND
7- COS INPUT FROM RX RADIO
8- GROUND
9- GROUND
10- GROUND (DB9 SHELL)
3.2 OUTPUT AMPLIFIER GAIN
This is a multi-turn, 10kΩ potentiometer that can be used to further adjust the output audio amplitude.
It is recommended to leave this potentiometer at the midpoint value for normal operations.
3.3 BUILT-IN AUDIO
The system contains a SGTL5000 Audio codec chip which provides stereo input and output capability so
you won’t require a USB sound card to have receive audio capability.
The stereo audio is split into 2 mono channels, channel 1 uses the RIGHT audio channel and channel 2
uses the LEFT channel.
Software is required to provide the mixing of the channels should you desire to blend channel 1 and 2
audio. Any base images provided by ICS-CTRL will have this built in by default.

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3.4 ANALOG TO DIGITAL CONVERTER
A MCP3208 is built into the system to provide
analog input capabilities with support for 8
channels with 12-bit resolution per channel.
Each channel is provided with some input
protection through a current limiting resistor
and a Zener diode. It is the user’s responsibility
to ensure the inputs are not over driven beyond
a 5V maximum input voltage to prevent damage
to the ADC unit.
Channel A0 has a unique configuration to allow
for the use of a LM335 temperature sensor
device. It is recommended to use this channel
last to minimize potential confusion due to the
unique configuration.
3.5 GPIO EXPANSION
As the repeater board consumes most of the
signals from the 40 pin header, an additional 8
pins are made available through a 16 pin header.
This header connects to PORT A on a MCP23017
IC, and provides input circuit protection through
Zener diodes which limit the input voltage to
3.5V maximum.
Caution should be exercised to ensure only 3.3V
logic levels are used to connect to these pins.
The GPIO expander provides the option to
include pull-up resistors should your circuit need
these, but are not turned on by default, you will
be responsible for configuration of these pins if used.
Connector Selection: Due to the tight spacing of the board, it is important to select mating connectors
that do not exceed the width of the male pin alignment blocks, or you risk mechanical interference with
the port 2 header. For custom cables we suggest using connector block 952-2037-ND from Digikey, or a
similar variant. STANDARD IDC RIBBON CABLE CONNECTORS WILL NOT FIT.

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3.6 GPS OPTION
An expansion header is provided so you may add an off-the shelf GPS
board (SparkFun.com #GPS-11058). The use of this GPS unit also
requires the purchase of qty 2, PN ED5908-ND from Digikey, and the
GPS antenna of your choice with SMA interface. We have tested
Sparkfun #GPS-00464, but any passive GPS antenna should work fine.
Installation of the GPS antenna requires the connectors be soldered
on the BOTTOM of the GPS board as indicated by the silk screen.
We suggest installing the pins first into the repeater board sockets,
mounting the GPS board to the pins and then soldering to ensure
proper alignment as the female sockets float a bit in the holes and
may also be slightly angled.
NOTE: using the GPS board is very close to the LCD flex cable socket,
and may interfere with the ability to use a touch screen depending on the cable used. We have
successfully folded back a ribbon cable while having the GPS unit installed, but the clearances are tight
and the tight bend radius may damage your flex cable, have a spare flex cable and proceed with
caution.
NOTE: “UART/GPS” switch must be in the correct position as shown for the
GPS to communicate with the Raspberry Pi platform.
3.7 I2C EXPANSION
A 4 pin header has been included to allow you to expand the I2C bus to include
your own devices, but you must ensure that the signals are 3.3V. Voltages
above 3.3V will damage both the Raspberry Pi and the repeater board. Zener
Diodes are included in the data signals, but should not be counted upon to
protect the boards from overvoltage.
It is recommended to utilize MCP23017 gpio expander device if additional gpio functionality is desired.
The MCP23017 device is recommended due to wide usage and support provided by current raspbian
distributions. Note: Use of this chipset requires a user developed Device Tree Overlay to prevent
interference with the PTT and existing GPIO expander functionality. The provided overlays only
support the chipset already on-board, which is part of the repeater board’s core functionality.

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3.8 SPI EXPANSION
A SPI expansion header has been included for the user to be
able to install any SPI device desired. It should be noted that
this header only supports 5V logic devices. If you install 3.3V
logic devices, they may become damaged.
It is the user’s responsibility to provide logic level translation if
a 3V3 device is used in the port.
The Chip Select CS1 has been routed to this port, which is
supported natively with Device Tree Overlays for convenience,
additional SPI devices can be used on this port as well, but the user is responsible for providing the Chip
Select connectivity.
It is recommended to utilize MCP23S17 gpio expander device if a Chip Select source is needed for
multiple SPI devices are desired. The MCP23S17 device is recommended due to wide usage and
support provided by current Raspberry Pi distributions.
3.9 I2S EXPANSION
A 10 pin header has been included to allow for specialized I2S
sound card devices to be used. This is provided for user design.
INSTALLED I2S SOUND CHIPS IN LOCATIONS U7 OR U9
MUST BE REMOVED PRIOR TO INSTALLING ANYTHING ON
THIS HEADER.
3.10 1-WIRE HEADER
A 3 pin header has been included to allow for specialized 1-wire devices to be
used. This is provided for user design and devices on this port are not supported
by ICS-CTRL.
This port connects directly to the processor and misconnected devices may cause
damage to the system. Please use appropriate precautions to prevent damage to you Raspberry Pi.