Arduino nKeyer User manual

nKeyer
A Flexible Arduino Nano-based Amateur Radio
Keyer Project from N7XG
June 26, 2020
Version 1g Board
Document Rev 1.2
N7XG, Salem, Oregon 97302
© 2011-2020 N7XG All rights reserved.
Published 2020
Printed in United States
N7XG (“Developer”) has made every effort to ensure the accuracy of this document. Developer makes no warranties with respect to this
documentation and disclaims any implied warranties of merchantability and fitness for a particular purpose. The information in this document
is subject to change without notice. Developer assumes no responsibility for any errors that may appear in this document.
The information contained herein is the exclusive and confidential property of N7XG, except as otherwise indicated.
We wish to also thank the Do It Yourself Community for the inspiration it has given us in the development of this product.
All other trademarks acknowledged.

nKeyer
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Table of Contents
1. OVERVIEW OF THE NKEYER........................................................................................................................3
1.1 SCHEMATIC...................................................................................................................................................4
2. ASSEMBLY INSTRUCTIONS..........................................................................................................................5
2.1 NKEYER BOARD BOM/PARTS LIST..................................................................................................................5
2.2 OTHER PARTS TO CONSIDER..........................................................................................................................6
2.3 NKEYER PARTS ASSEMBLY ............................................................................................................................7
2.3.1 First Things First................................................................................................................................7
2.4 ASSEMBLY GUIDE..........................................................................................................................................8
2.4.1 Install Parts........................................................................................................................................8
2.4.2 Setting the BUCK ........................................................................................................................... 12
2.4.3 Installation final assembly .............................................................................................................. 12
2.5 PROGRAMMING........................................................................................................................................... 12
2.6 TEST.......................................................................................................................................................... 13
3. CONNECTORS / OPTIONS.......................................................................................................................... 14

nKeyer
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1. Overview of the nKeyer
This documentation covers the construction of the nKeyer board and general use. It
approaches this task as a learning exercise for new builders, so that they can develop
proficiency and self-confidence. The project itself is quite simple and if you follow the steps you
will have a working board able to use for amateur radio.
The nKeyer is a simple Arduino based device designed to act at its basic level, as a stand-
alone “electronic keyer” with a Morse code paddle. Flexibility has been built in providing
additional features such as:
•Based on the Open Hardware K3NG Nano Keyer hardware.
•Uses the K3NG Arduino open-source firmware here:
https://github.com/k3ng/k3ng_cw_keyer . Also see:
https://nanokeyer.files.wordpress.com for project details on using and programming the
code.
•Compatible with the Nano Keyer Rev D open hardware design.
•USB interface for programing AND keyer control.
•Winkey compatible
•Output to drive a transmitter if desired.
•Can be used with or without a 1602 SPI text display.
•Provides 8 pushbutton inputs for providing canned Morse coded messages.
•Provides an optional keyboard interface for command line control if desired.
•Additional optional features that make it useful as a CW Contest Keyer Addon.
•5V powered, or OPTIONALLY can be powered from a 7- 23 volt input through a small
onboard “buck converter” that is adjusted to 5v output (details later in this guide).
•Power and Transmit LED indicators.
•Morse speed is adjustable, on the fly, from a rotary encoder or simple potentiometer
(your choice)

nKeyer
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1.1 Schematic

nKeyer
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2. Assembly Instructions
This section covers the construction of the nKeyer. It approaches assembly as a learning
exercise for new builders, so that they can develop proficiency and self-confidence. The build
is quite simple and if you follow the steps carefully, you should have a working board when you
are done. Additional information and guides on techniques and tools can be found in the
“Tools and Parts ID Guide” at: www.renard-plus.com/files/Tools_and_Parts_ID_Guide.pdf
2.1 nKeyer board BOM/Parts List
Picture
Designators
Description
Qty
Note
R1, R5
470 ohm resistor ¼ watt
2
R2, R4, R6, R7, R9-R14
1.0k ohm resistor ¼ watt
10
R3
10k ohm resistor ¼ watt
1
R8
100 ohm resistor ¼ watt
1
C1, C2, C4
.01uf (10nf) 50v
monolithic ceramic cap
3
C3 Optional for DC
blocking on the audio out.
Jumper wire (or 1uf -
220uf electrolytic or
tantalum cap)
1
Typically not used -
jumper across
C5
220uf 16v electrolytic
1
D1
1N4148 diode
1
U1 (opt but
recommended)
1x15 pin 2.54 pin
spacing female header
2
Allows the Nano to be
removed replaced
U1
Arduino Nano 3.0
16MHz, 5V,
ATMEGA328P
1
U2 (opt for >5v input)
Mini “360” Buck
regulator (adjust to 5v
output)
1
If your input is 5V, this
can be left out by placing
a jumper across JP1
“Buck bypass”
Q1, Q2
2N2222a or 2N3904
NPN Transistor
1
J3-PWR LED, J5-TX LED
LED Standard 5mm (any
color)
2
Place header pins if LED
will be mounted on the
enclosure.
J1-1x4, J2-1x2, J4-1x3,
J6-1x2, J8-1x3, J9-1x2,
J10-1x5, J11-1x5
Single row headers –
various
30
pins
Cut to appropriate # of
pins for the location
J7 Buttons 2x8
2x8 dual row header
1

nKeyer
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2.2 Other Parts to Consider
The following are additional parts you may want to consider:
•Enclosure (example the 100x68x50 mm “clear plastic project box” for
around $3 works well)
•5V (no buck) or 7V-24V power supply with buck installed (9 volt battery
works)
•A paddle key to enter Morse code
•8 ohm speaker to hear the Morse tones
•1601 LCD with Serial (I2C / SPI) interface
•Arduino Rotary Encoder module or 10K potentiometer for the
Morse speed setting
•PS/2 or USB keyboard
The nKeyer is quite flexible and provides a wide range of options to try. The code for the
board has an extensive set of compiled features, most that the nKeyer will support.

nKeyer
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2.3 nKeyer Parts Assembly
This is a fairly simple device to assemble and test at a basic level. It is easiest if you follow
these instructions, checking off steps as they are performed. This will lead you through the
assembly installing components generally from shortest/smallest to tallest.
2.3.1 First Things First
1. Begin by inspecting the PCB to look for any defects such as cracks or breaks. The
holes on the board should be open on both sides.
2. Next inspect and sort out the various parts for the board. Make sure you understand
which parts are which, and things like resistor codes and component orientation. A
Google search will yield a plethora of information including resource sites like Wikipedia.
3. Follow the assembly guide as follows in the next section.

nKeyer
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2.4 Assembly Guide
Generally, the following component assembly order is grouped from shortest to tallest parts to
make assembly easier. Special instructions for component orientation should be listed if a
component has any. Don’t stress it- we try to make this as easy as possible!
2.4.1 Install Parts
Step
Instructions
nKeyer
1
Install the 1N4148 at location D1. Solder and
clip leads.
Note: The diode is polarized and must be
installed with the proper orientation. The end
with the band (cathode)
goes towards the right
side of the board as
shown and as indicated on the board
silkscreen.
2
Install the two 470 ohm (yellow-violet-brown)
resistor at location R1 and R5. Solder and clip
leads.
Note: Resistors do not have a specific
orientation.
3
Install the ten 1K (brown-black-red) resistors at
location R2, R4, R6, R7, R9-R14. Solder and
clip leads.
4
Install the 10K (brown-black-orange) resistor at
location R3. Solder and clip leads.

nKeyer
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Step
Instructions
nKeyer
5
Install the 100 ohm (brown-black-brown)
resistor at location R8. Solder and clip leads.
6
Install a jumper wire at location C3. Solder
and clip leads.
Note: a clipped resistor lead can be used as a
jumper wire. Alternatively a 1uf up to 220uf
electrolytic or tantalum cap can be used (Note
polarity!!) however, audio volume may be
inversely impacted. This option allows
additional DC blocking out to an amplified
audio device.
7 
Install the three 0.01uf Ceramic Capacitors at
locations C1, C2 and C4. Solder and clip
leads.
Note: Bypass caps do NOT have a specific
orientation. .01uf is also known as 10nf and
can be marked 103 or 103K.
8
Install two 2N2222 NPN Transistors (or equiv)
at Q1 and Q2.
Note: Transistors do have a polarity. The flat
side of the transistor should match the flat side
shown on the silkscreen. Flat side goes
toward the left as shown. 2N3904 is a good
substitute for a 2N2222a

nKeyer
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Step
Instructions
nKeyer
9
For the power and transmit key
indicators, either install two 1x2 male
headers at J3 and J5 (for remote
case mounted LEDs) or the install
the 2 LED’s at those locations.
Solder and clip leads (if applicable).
Note: LEDs have a specific
orientation. The flat side of the LED is
negative (often the short lead) and goes
toward the bottom of the board. The longer
lead (opposite side of the LED from the flat
spot) goes into the hole marked + toward the
top of the board (as shown and as indicated on
the silkscreen).
10 
Install the male header pins into the remaining
locations J1 (KBD 1x4), J2 (PWR 1x2), J4
(POT 1x3), J6 (TX Out 1x2), J8 (Paddle 1x3),
J9 (SPKR 1x2), J10 (LCD 1x5) and J11
(Encoder 1x5). Solder.
Note: J11 could be populated with a 1x5
FEMALE connector allowing for the rotary
switch to be plugged straight in with its existing
male header.
11 
Install the 2x8 male header at J7. Solder
12 
Install the two 2.54 1x15 FEMALE headers at
U1.
Note: Optional but highly recommended so the
Nano can be swapped if needed.
If you do NOT install the headers here, do
NOT install the Nano module yet- we will need
to set/test the power first.

nKeyer
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Step
Instructions
nKeyer
13 
Install the 220uf 16V electrolytic
capacitor at location C5. Solder
and clip leads.
Note: Be sure that the (+) lead is
installed in the hole marked with a “+”
symbol. The (+) lead is usually longer
than the (-) lead, and the (-) lead is usually
identified by a black or white stripe on the
capacitor.
14a
-OR-
If your input voltage is 7-24v (like a 9v battery),
install the Mini-360 buck converter at indicated
buck location. Solder.
Note: The buck converter has a specific
orientation and should match the silkscreen
diagram. It can be mounted using either single
male header pins at the four corners, OR with
scrap wires such as the trimmings from the
resistors, or with other wire. Please note that
you will need to set the buck to output 5v
during test so be sure the Nano is NOT
installed before you set it to 5v!!
14b
If your input voltage will be clean 5v DC, then
you can omit the buck converter and just place
a jumper wire across JP1.

nKeyer
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2.4.2 Setting the BUCK
Please follow this if you are using higher input voltage than 5V and have installed to optional
buck converter. BEFORE installing the Arduino Nano board onto the nKeyer, the buck
converter must be set for 5v output. This is accomplished by applying the supply voltage (7v -
23v) to J2 “PWR In” and measuring the buck output pins with a multimeter or volt meter, then
adjusting the small potentiometer on the buck board until the voltage measures 5v.
2.4.3 Installation final assembly
15 
Install the Nano board into the female headers
installed at Step 12.
Note the Arduino Nano has a specific
orientation. The USB connector on it should
be positioned toward the bottom as shown
here
2.5 Programming
Please refer to the original developer’s firmware and upload instructions here:
https://nanokeyer.wordpress.com/downloads-3/
You will need to set the compile options in the K3NG Arduino Code from the Nano Keyer to
match the options you are implementing on your board. The main setting is to set the “Nano
Keyer Rev D” option. There are quite a few interesting options in the code, however, code
space in the Nano is limited so you will need to pick and choose what you need.
Buck voltage
adjust
potentiometer
Buck VOut +
Buck VOut -

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2.6 Test
Apply power. If you implemented the display, you should get a title and a “hello” tone from the
nKeyer audio out or speaker. Attach your paddle and verify you get the “dits” and “dahs” that
you expect. Try out other features that you may have enable in the code, like Winkey, or
memories.
That completes the construction of the nKeyer board!

nKeyer
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3. Connectors / Options
The nKeyer was designed to be very flexible, allowing you to decide what you do or do NOT
wish to hook to it. As such there are many options for connections to use. Loosely, these can
be classified as Needed, Recommended, and Optional.
1. Power in (J2: PWR IN Pinout = “+ -“) –5V (with no buck jumper installed) or 7-23v in
with the Mini-360 buck installed. NEEDED
2. Speed Pot (J4: SPD_POT Pinout = 3 pot pins) –connect to a 10K potentiometer to
adjust the CW speed. Requires the code to be set for the speed pot option. Use this
OR the rotary encoder. OPTIONAL
3. Buttons (J7) –Up to 10 function buttons (determined by the code settings). A typical
configuration requires at least two buttons to be used. Button 1 connects to the top
most two pins (horizontally across from each other), and button two connects to the two
pins next down. Minimum TWO RECOMMENDED / NEEDED
4. Rotary Encoder (J11: Rotary Enc Pinout = “GND, 5V, SW, DT, CLK”) –The
code supports the connection of an inexpensive rotary encoder used with
Arduino projects to control CW speed and potentially other functions. This
style of encoder can be found on Ebay for $1 or less. Search for “Arduino
Rotary Encoder”. This connector is designed to connect straight to an Arduino
encoder as pictured. RECOMMENDED
11.Power in
12.Speed
pot
3. Buttons
10.Rotary
encoder
1. LCD
9. Keyboard
7. Power
LED
8. Transmit
LED
6. Transmit
Out
5. Paddle
Input
4. Speaker
Out
2. Buck
Bypass

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5. LCD (J10: LCD Pinout = “GND, 5V, SDA, SCL, 3.3v” ) –
The board will drive a Serial LCD character display.
Most display run on 5v and will hook straight to the first 4
pins –HOWEVER- if the display you have needs 3.3v,
that is also provided on the connector. The code is
designed specifically for a “Serial 1602 LCD” that can be
found on ebay for around $2. RECOMMENDED
6. Keyboard (J1: KBD Pinout = “GND, 5V, KBD-CLK, KDB-
DATA”). In theory, the code supports attaching a P/S2 or USB keyboard. This is an
untested option as of publication of this document. OPTIONAL
7. LED Power (J3: PWR LED Pinout = “LED+, LED-“)–This is a spot to directly hook an
LED to indicate the power is on. There is a limiting resistor that keeps the
voltage/current within range of modern 2.7 - 3V LEDs. RECOMMENDED
8. Transmit LED (J5: TX LED Pinout = “LED+, LED-“)–This attaches to an LED to
indicate when the Transmit Out (TX Out) is active. RECOMMENDED
9. Transmit Out (J6: TX OUT Pinout = “TX+, TX-“) –This connection is used to key up
your transmitter to send out code via the speaker connection. RECOMMENDED
10.Paddle Input –(J8: PADDLE Pinout = “L, GND, R”) This connector is used to connect
to your Paddles to have the nKeyer send out morse tones. One pin is the “Dit”, one is
the “Dah” and the middle pin is ground to the paddle. NEEDED
11.Speaker Out (J9: SPKR Pinout = “Spkr+, Spkr-“) –This connection is to either hook
directly to a speaker, or to the microphone input on your transmitter to allow the nKeyer
to send out morse. NEEDED
12.Buck Bypass (JP1: No Buck Jumper) –If you will be using a clean 5V regulated input on
J2 PWR IN (or will power off the USB connection on the Nano), you do not need to
install the Mini-360 Buck Converter, but instead can jumper JP1. This will connect J2
straight to the 5V power bus on the board. If you attach any power higher than 5V in
this configuration, it WILL blow up the board. Either a MINI-360 or a jumper is NEEDED