QRP Labs QLG2 User manual

QLG2
GPS/GNSS
Receiver
This manual is for the QLG2 GPS/GNSS Receiver module
Firmware version 1_ .QG2, 1_ a.QG2 and 1_ b.QG2
Contents
1. Introducon....................................................................................................................................................2
2. Geng to know your QLG2............................................................................................................................2
3. Assembly.........................................................................................................................................................5
3.1 Assembly for bas c operaon....................................................................................................................5
3.2 Use w th QCX, U3S, Clock, VFO, ProgRock etc. k ts...................................................................................6
3.3 USB connector..........................................................................................................................................6
3.4 USB to Ser al converter.............................................................................................................................7
3.5 Power ng the board from the USB port..................................................................................................10
3.6 Status LEDs.............................................................................................................................................11
3.7 F ng an ultracap (a.k.a. supercap)........................................................................................................12
3.8 6-p n nterface header............................................................................................................................13
3.9 Jumper w re con;guraon......................................................................................................................14
3.10 Interface con;guraon.........................................................................................................................14
3.11 M crocontroller con;guraon...............................................................................................................16
3.12 Connecng an LCD module...................................................................................................................17
3.13 QLG2 Commands..................................................................................................................................19
4. F rmware update procedure.........................................................................................................................20
5. C rcu t d agram (schemac) and descr pon................................................................................................23
6. Tesng..........................................................................................................................................................26
7. Acknowledgments........................................................................................................................................27
8. Resources.....................................................................................................................................................27
9. Document Rev s on h story...........................................................................................................................27
QLG2 manual for ;rmware 1.00a 1

1. Introduction
The QLG2 GNSS (Global Navigation Satellite System) receiver module is an upgrade over
the former QLG1 ith higher performance and highly flexible features:
•Multi GNSS satellite constellation receiver supports GPS (US), Galileo (Europe),
GLONASS (Russia) and Beidou (Chinese) - (default GPS + Beidou) - giving a faster
more accurate position fix – Module is E108-GN01 (GK9501 GNSS chip set)
•Serial to USB converter, using onboard USB B connector, for convenient interface to
PC soft are if required - no drivers required. Jumpers select either the GPS serial
data, or your o n externally connected serial data, for example you could use this as
a USB to Serial data converter for CAT control of QCX, QCX+ and QCX-mini
transceivers.
•Can optionally be connected to a standard 1602 LCD, in the same style as the
Ultimate3S, VFO and Clock kits, to GPS date, time and satellite information using
the onboard microcontroller.
•Supplied ith included magnetic-mount active antenna, approx 2m coax and SMA
connectors
•Supply voltage range 3.3 to 6V.
•Board 80 x 37mm (Same as, and compatible ith, Ultimate3S, VFO and Clock kits).
•Onboard LEDs for status indication: Red (Po er), Yello (Serial data) and Green
(PPS).
•2.8 to 5V logic level conversion to provide 5V serial data for full compatibility ith all
QRP Labs kits.
•Supports 2.8/3.3V logic OR 5V logic (jumper ire selected)
•SMD assembly already undertaken by factory facility - only SMA connector, and
optional USB B connector to solder.
•Space provided for optional ultra-capacitor for faster hot-start
All QLG2 GPS modules are comprehensively tested before shipment including:
•Active antenna ith 2m coax and SMA connector functions correctly
•Satellite reception and Time To First Fix is under 1 minute
•Serial data and 1pps outputs are correctly present
•USB to Serial data converter operates properly (vie serial data in PC terminal)
•Microcontroller firm are update procedure test
PLEASE READ THE BASIC ASSEMBLY AND USE
INSTRUCTIONS IN THIS MANUAL VERY CAREFULLY BEFORE
APPLYING POWER TO THE BOARD!
2. Getting to know your QLG2
There are only FOUR parts in the QLG2 kit:
1. 80 x 37mm PCB ith assembled SMD
2. Active antenna including 2m coaxial cable and SMA connector
3. SMA connector for installation on the PCB
4. USB-B type connector for optional installation on the PCB-mount
The parts list of the PCB is provided later in this manual in the circuit description section.
QLG2 manual for ;rmware 1.00a 2

Kit contents:
Know your QLG2:
QLG2 manual for ;rmware 1.00a 3

With reference to the above photograph, looking anti-clock ise from left:
•GNSS Module: The E108-GN01 GNSS receiver module, multi-satellite system
capable (GPS and Beidou enabled by default).
•Antenna SMA Connector (supplier): Can be board edge-mounted or at 90-degrees
standing up on the board (DO refer to important assembly instructions later).
•LED enable jumpers: these are ired by default, and connect the signals to the
onboard LEDs. If you anted to use external LEDs for example in a front panel, you
ould cut the tiny traces under these jumpers (see later section).
•Status LEDs:
◦Po er (RED): al ays lit
◦Serial Data (Yello ): flashes once per second in time ith the serial data burst
◦1 PPS (Blinding Green): flashes once per second hen a 3D satellite lock is
acquired
•External LED connect: Three LEDs may be connected here using ires if you prefer
external LEDs to the onboard SMD LEDs.
•6-pin interface: this provides six pads:
◦GND
◦GNSS 1pps
◦GNSS serial data
◦TxD serial data (for USB to Serial converter)
◦RxD serial data (for USB to Serial converter)
◦+5V
•Option Jumpers: configure ho the six serial port pads are connected, allo ing
either 2.8/3.3V logic or 5V logic levels
•USB (4 positions): a Type B USB connector is supplied, suitable for a standard USB
A – B cable. It can be installed either facing to the right side of the board, or facing
the bottom side of the board. Additionally there are pads for a micro-USB connector
if you should happen to prefer that.
•4-pin interface: pads for QCX, U3S etc: the standard QRP Labs 4-pin connector:
+5V, Gnd, Serial Data (TxD) and 1PPS
•LCD Contrast trimmer: When installing the optional 1602 alphanumeric LCD module,
a 22K trimmer potentiometer is fitted here to permit contrast adjustment
•Config jumpers: these are read by the microcontroller at po er-up, and determine
configuration options such as baud rate; they can also be used to enter the
bootloader (firm are update) mode
•LCD Port: The pinout is in the exact same position as on the QRP Labs Ultimate3S,
Clock or VFO kits; a standard 1602 alphanumeric LCD module can be bolted onto
the board here, using 16-pin male/female pin header connectors, 12mm plastic hex
spacers and eight M3 6mm plastic scre s (as on the aforementioned QRP Labs
kits).
•Space for Ultracap: 5mm-spaced pads suitable for installation of an Ultracap for
ephemeris backup purposes; this provides faster hot-start.
The board size is 80 x 37mm, and the holes in the four corners are at exactly the same
positions as on the Ultimate3S, Clock and VFO kits; therefore the board can be stack-
mounted behind these kits on suitable spacers (12 or 25mm).
These features ill be described in more detail in subsequent sections.
QLG2 manual for ;rmware 1.00a 4

Compatibility
Straight out of the box, if you simply install the coaxial connector and plug in the antenna,
the QLG2 is back ardly compatible by default ith the former QLG1 kit. It is therefore
directly compatible ith all other QRP Labs kits:
•QCX-series CW transceivers (QCX, QCX+ and QCX-mini)
•Ultimate3S (and preceding kits in the Ultimate- series)
•Clock kit
•VFO/Signal generator kit
•ProgRock kit
3. Assembly
3.1 Assembly for basic operation
Assembly of this kit is EXTREMELY straightfor ard; at the minimum, you need only solder
in the SMA connector. This can be installed horizontally or vertically (belo left and right,
respectively), to suit your particular application.
Vertical installation: IMPORTANT! The body of the SMA
connector WILL DEFINITELY short to the center pad of the
component footprint on the board. This ill not only short out
the antenna, rendering it completely ineffective, it ill also dra
high current from the GNSS module through the 10-ohm
resistor R2. You ill soon note the temperature rise of the
GNSS module as ell as the 3.3V voltage regulator chip (you
don’t need to ask me ho I kno ...).
Therefore it is essential to create a little gap between the
body of the SMA connector and the board.
The best ay to do this is via small piece of paper. It’s a simple,
cheap and effective solution.
Cut a small piece of paper as sho n (above right), place it on
the board and push the center pin of the SMA connector
through the paper.
Solder the SMA connector in place as usual. Don’t overdo the
heat and burn the paper.
QLG2 manual for ;rmware 1.00a 5

Horizontal installation: The SMA connector happens to fit the board nicely too in the
horizontal, edge-mounted position. Place it ith the center pin on the top side of the board,
and t o of the corner pins on the bottom side, and solder in place. The other t o ground
pins can be ignored. This orks very ell.
3.2 Use with QCX, U3S, Clock, VFO, ProgRock etc. kits
In this application, you need only plug in the antenna coax SMA
connector and the QLG2 is ready to use. It is entirely compatible
ith the former QLG1 kit and the 4- ay pin header pads at the
right side of the board can be used in the same ay as a QLG1
kit.
+5V po er can be supplied to the module via the +5V
connection if desired.
These signals are also available on the 6- ay pin header pads
at the bottom of the board edge. If you install the USB-B
connector in the position facing out from the right-hand edge of
the board, the body of the connector ill block access to the 4-pin header. In this case, if
you ish to connect to these 4 signals, you can do so at the 6-pin interface
NOTE: The 4-pin header “TXD” connection is not the same as the “TXD” connection on the
6-pin header at the bottom board edge. On the bottom edge connector (6-pin) the signals
named TXD and RXD are the microcontroller serial ports that access the USB to Serial
converter. On the 6-pin connector, the pin labeled “SER” on the PCB silkscreen, and
“GPS_TXD” on the schematic, is actually connected to the pin labeled “TXD” on the 4-pin
header.
3.3 USB connector
For all but the most basic use of the QLG2, you ill likely ish to install the USB B
connector (supplied) or if you prefer, a micro-USB connector (not supplied).
The USB connector is used for t o purposes:
1. To provide a USB to Serial converter, hich can be used either to stream the GNSS
NMEA serial data to the PC, or as a separate USB to Serial converter for other
purposes, for example, for providing CAT control to a QCX-series CW transceiver kit.
(This is described in a later section).
2. In bootloader mode, the USB connector enables the functionality of the QRP Labs
Firm are Update (QFU) procedure. (This is described in a later section).
In the diagram belo , you ill note that the supplied USB-B connector can be installed ith
its socket facing out from the bottom of side of the PCB, or from the right side. These are
coloured orange in the diagram. There are also pads provided for a micro-USB connector
(not supplied), again facing do n or to the right; these are coloured red in the diagram.
Which of these positions you choose to install the connector in, has no bearing on the
operation of the unit; it is only a matter for you to choose hatever ill be most suitable in
your enclosure or application.
QLG2 manual for ;rmware 1.00a 6

3.4 USB to Serial converter
The primary application of the microcontroller on the QLG2 board, is to provide a USB to
Serial converter.
The microcontroller is programmed to appear as a standard Virtual COM Port USB device
class, hich means that no additional drivers are required on any modern operating
system. The standard drivers are al ays already included. This greatly simplifies operating
the device. In comparison to some other Serial to USB converters hich end up in an
endless fight ith driver issues, QLG2 “just orks”.
There are many Terminal Emulator programs available for PCs. Personally I normally use
PuTTY, hich is available for both Windo s and Linux operating systems. But it does not
matter, any favourite Terminal Emulator ill ork fine. The Serial Monitor of the Arduino
IDE is another possibility hich I use sometimes.
On opening the Terminal Emulator you ill need to choose the USB Virtual COM port to
connect to; this is different depending on hether you are using Windo s or Linux.
1. On Linux, the QLG2 ill appear as /dev/ttyACM – or perhaps ACM1, ACM2 etc if
you already have similar devices connected to your system.
2. On Windo s, the QLG2 ill appear as a COM port for example, COM1, COM2 etc. I
don’t kno of any easy ay to find out hich COM port number Windo s has
assigned, except to open the device manager and look at the listed USB devices.
Note that it does not matter hat baud rate you select in the terminal emulator, since USB
does not run at any particular rate, and the baud rate of the QLG2 USB to Serial converter
is determined by jumpers on the board (see later section).
On connecting the terminal emulator, you ill see lots of text scroll by, in bursts once per
second; these are the NMEA sentences output by the QLG2’s GNSS module. By default,
the QLG2 jumpers are configured to route the GNSS module’s serial data to the
microcontroller’s USB to Serial port.
The follo ing screenshot sho s an example of hat it could look like.
QLG2 manual for ;rmware 1.00a 7

Using a Terminal Emulator for testing CAT on a QCX-series CW transceiver
Remember that in any serial communications operation of this type, the TxD (transmit)
output of the host controller, has to be connected to the RxD (receive) input of QCX;
correspondingly the RxD (receive) input of the host controller has to be connected to the
TxD (transmit) output of QCX. In other ords, you have to get your ires crossed –
correctly.
An important note is required here. QCX firm are requires that incoming CAT commands
are a rapid succession of characters arriving at 38400 baud. The permissible delay
bet een characters of a command is a fraction of a millisecond. You certainly cannot type
that fast. Even I can’t type that fast. Therefore, any text you type into a PuTTY (or most
other) terminal emulators ill not produce the desired result on the QCX since the QCX
firm are ill time hile out aiting for the next character. (Note that normal CAT host
programs do not have this issue, they send commands as a rapid burst of characters).
There are t o possible ays around this:
1. Type the command you ant to send to QCX, in another indo such as a text
editor of some sort; then copy-and-paste it into the Terminal Emulator indo . This
ill ensure that the hole text sentence is sent ith the characters in quick
succession, not leaving gaps here the QCX times out.
2. Use the Serial Monitor application inside the Arduino IDE – this also functions as a
very basic, very limited, Terminal Emulator – but it has the quirk (useful in this case)
that there is a separate box at the top of the indo here you type the text to be
sent, and it does not actually get sent until you hit return or click the “Send” button.
So again, this ensures that the text is all sent in one rapid lump, hich is acceptable
to the QCX.
An example screenshot of the Arduino Serial monitor is sho n belo , again sho ing the
NMEA sentences scrolling past.
QLG2 manual for ;rmware 1.00a 8

Using a Terminal Emulator for sending commands to the E1 8-GN 1 GNSS module
By default, the USB to Serial converter is connected to the GNSS receiver module. The
module accepts a variety of commands hich can be used, among other things, for:
•Changing the baud rate (default is 9600 baud)
•Changing hich NMEA sentences are output
•Enabling or disabling the various GNSS systems (GPS, Galileo, GLONASS and
Beidou)
You can type the command in full on the Terminal Emulator, and it ill be transferred to the
GNSS module by the QLG2 USB to Serial converter.
A common error is to not calculate the checksum properly; these are the last t o characters
of the command string. The actual command is prefixed by a $ and terminated by a *
follo ed by the t o checksum characters. All the ASCII byte codes of the command
bet een the $ initiator and * terminator, but not including the $ and the *, are logically
XOR’ed together, hich produces the checksum.
If this seems like too much of a headache, and actually it really IS too much of a headache,
then asking Google about “NMEA checksum calculator” ill find you lots of easy calculators
that do this for you. For example https://nmeachecksum.eqth.net/ .
QLG2 manual for ;rmware 1.00a 9

3.5 Powering the board from the USB port
In some applications, you may find it convenient to po er the QLG2 board from the USB
port.
In this case, simply solder a jumper ire across JP11 as sho n in the diagram belo .
Tip: I am in the habit of making my soldered jumper ires as a little loop, standing up about
5mm from the board surface; this is because even if I am 100% sure no , that this ill be a
permanent connection… all too often I find for hatever reason, I ill change my mind later.
To make it easier to remove, or to temporarily disable, a jumper ire – I just make a 5mm-
high loop rather than a ire laying near the PCB surface. The 5mm loop is a lot easier to
cut and if necessary, to remove, than a wire tight flat against the board surface.
If you already feel no that it ill not necessarily be a
permanent connection, then fit a 2- ay pin-header
and use a header jumper, as pictured (right).
No you might be thinking, “I have pin headers, but I
don’t have those fancy jumpers you used to find (and
maybe still do) on old PC Motherboards, and I don’t
fancy aiting for Amazon, eBay, hoever”… ell
never fear, for necessity is the Mother of invention – I
don’t have those fancy jumper plugs either, I just
improvise using female pin header connectors. Which
aren’t even the right right size (2- ay) but can be cut
to leave just t o pins… and then gently bend over the
t o pins to ards each other and solder in the middle
(see photo, right).
IMPORTANT: never connect the jumper to power
from USB, and at the same time supply +5V power
from some other source to the other connection
pads! NEVER, EVER!
QLG2 manual for ;rmware 1.00a 10

3.6 Status LEDs
Just like it’s predecessor the QLG1,
the QLG2 module has the same
three LED status LEDs.
In the case of QLG2, these are
0603-size SMD LEDs installed on
the PCB near the GNSS receiver
module.
LED 1 (red) is the Po er LED and is
al ays lit hen QLG2 is po ered.
LED 2 (yello ) is the Serial data
LED and pulses in time ith the
serial data. Note that in a departure from the QLG1, this LED is actually OFF during the
data burst ( hereas on QLG1 it is ON during the data burst). The reasons for this are
explained later, in the circuit explanation section.
LED 3 (blinding green) is the 1pps indicator and flashes once per second, for 0.1 seconds,
coincident ith the 1pps pulse hose leading edge indicates the exact UT second. This
LED only starts blinking once a satellite lock (3D fix computation) has been achieved.
Together, these three LEDs provide an accurate diagnosis of correct operation of the
QLG2.
Connecting external LEDs
You may ish to use external LEDs instead of
the onboard ones. For example, you may ish to
make the LEDs visible on the front panel of your
equipment. After all, hich of us does not like
blinking lights on his equipment, and generally
the more the merrier.
In this case, you can connect ires at pin header
PH1, as follo s in the diagram (right).
The cathodes (negative, indicated by black lines)
of the LEDs are connected to the pads nearer
the center of the board; the anodes (positive,
indicated by red lines) are connected to the pads
nearest the board edge. The sequence of the
pads, is as three pairs from left to right, as
Po er (RED), Serial data (YELLOW) and 1pps
(GREEN) – in other ords, the same order as
that of the SMD LEDs on the board.
You ould also need to cut the thin exposed
tinned copper traces on the underside of the
PCB, in order to disconnect the onboard LEDs.
This should be done ith a sharp knife, carefully
so as not to damage any other nearby traces.
QLG2 manual for ;rmware 1.00a 11

3.7 Fitting an ultracap (a.k.a. supercap)
There is a place on the QLG2 board to fit an ultracap (a.k.a. supercap). This is a lot more
reliable means of providing backup po er, than the little rechargeable battery on the QLG1.
Backup po er permits the operation of the internal Real Time Clock (RTC) in the GNSS
module and also retains the do nloaded satellite ephemeris data, hich ill enable a hot-
start (satellite fix computation) ithin a second or t o of po er-up.
Most amateur radio applications ill not need this, but the pads are made available on the
board in case you do ish to use it.
Be careful to observe the correct polarity to avoid a possible bang and a nasty chemical
mess (don’t ask me ho I kno about this, either).
The photograph sho s a 0.47 Farad, 5V capacitor installed on the QLG2 board. The pads
are separated by 0.2-inches (5.08mm) and the capacitor fits perfectly. This capacitor
appears sufficient to backup the QLG2 GPS for at least 12 hours.
QLG2 manual for ;rmware 1.00a 12

3.8 6-pin interface header
At the center of the QLG2 board’s bottom edge, is a 6-pin header that provides access to
the po er supply rails, the GNSS outputs, and the Serial port of the USB to Serial
converter.
The 1pps, Serial data, TXD and RXD signals can be configured to be either 2.8V/3.3V logic
level, or 5V logic level. The configuration is done using jumper ires that ill be described
in the next section. Note that 2.8V logic ill be compatible ith 3.3V systems, ithout issue.
From left to right:
•Po er supply ground.
•1pps: 1 Pulse Per Second output from the GNSS module; by default this pulse is 0.1
seconds ide and it is sent once per second. By default, the voltage level is 5V
hich is suitable for use ith QRP Labs products such as QCX, Ultimate3S, VFO,
ProgRock and Clock kits.
•SER: The NMEA serial data output from the GNSS module. By default this is at 9600
baud and is 5V logic level, hich is suitable for use ith QRP Labs products such as
QCX, Ultimate3S, VFO and Clock kits. Note that this signal is connected to the “TxD”
signal of the 4-pin header on the right side of the board.
•TXD: Serial port transmit signal; anything sent from the USB Terminal Emulator (for
example), is delivered to this transmit output pin. By default the baud rate is 9600
baud and the voltage level is 5V.
•RXD: Serial port receive signal; hen the jumper ires are configured to connect this
signal to the Serial to USB Converter, data arriving on this port is transferred to the
USB host. By default this signal is NOT connected to the Serial to USB port, hich is
by default connected to the GNSS module. This RXD (receive) pin is tolerant of 2.8,
3.3 or 5V logic levels and automatically converts this to 3.3V for the microcontroller
that implements the serial to USB converter.
•+5V: Po er supply positive. It is nominally 5V, but in fact you could po er the QLG2
module from any positive supply voltage in the range 3.3V to 6.0V, and the onboard
voltage regulator ill provide 3.3V to the GNSS module hich is its correct supply
voltage. NEVER connect both USB power supply via JP11, and an external
power supply.
NOTE that the 5V logic levels referenced above, assume a 5V supply voltage to the QLG2;
if you use a different supply voltage in the range 3.3V to 6.0V then the “high” logic level ill
be at that different supply voltage, not 5.0V.
QLG2 manual for ;rmware 1.00a 13

3.9 Jumper wire configuration
QLG2 provides a great deal of flexible functionality. Configuration of the module is done by
jumper ires, of hich there are quite a fe on the board.
As discussed in the former section headed “Po ering the board from the USB port”, you
may either solder in actual jumper ires, or pin headers and jumper pin connectors (not
supplied).
The diagram belo sho s the default jumper ire configuration, these are actually tinned
copper traces on the underside of the board. If you ant to change any of the defaults, you
must remember to carefully cut the traces under the board, ith a sharp knife, taking care
to avoid any nearby traces. This is described in the former section headed “Connecting
external LEDs”.
The jumpers fall into four categories:
1. Onboard LED enable: discussed above in section headed “Connecting external
LEDs”
2. Po er from USB: discussed above in section headed: “Po ering the board from the
USB port”
3. Interface configuration: discussed in follo ing section
4. Microcontroller configuration: discussed in follo ing section
3.1 Interface configuration
The configuration of the 6-pin interface (and indeed, the 4-pin interface on the right edge of
the board) is controlled by the jumper ire area above the 6-pin interface pin header pads.
In the default configuration (specified by the tinned copper traces jumper ires), all outputs
are 5V logic level, the RXD interface pin is not connected, and the GNSS RXD pin is
connected to the microcontroller (USB to Serial port)’s TXD pin.
QLG2 manual for ;rmware 1.00a 14

In the follo ing description, the nomenclature
adopted is – as illustrated in the diagram
(right):
UPPER: means the jumper ire is connected
from the center of the group of three pads, to
the top pad.
LOWER: means the jumper ire is connected
from the center of the group of three pads, to the lo er pad.
1. PPS voltage level:
UPPER: 5V logic level (DEFAULT)
LOWER: 2.8V logic level
2. SER voltage level (GNSS module serial data output, hich is the TXD pin on the 4-pin
header at the right of the board):
UPPER: 5V logic level (DEFAULT)
LOWER: 2.8V logic level
3. TXD voltage level (the USB to Serial converter transmit output pin):
UPPER: 2.8V logic level
LOWER: 5V logic level (DEFAULT)
4. RXD source ( here the USB to Serial converter receive signal is connected to):
UPPER: Receive signal is connected to the GNSS Serial data output (DEFAULT)
LOWER: Receive signal is connected to the RXD pin for external use
5. GNSS RXD source ( here the GNSS receive signal is connected to):
UPPER: GNSS RXD is connected to the USB to Serial converter transmit signal
(DEFAULT)
LOWER: GNSS RXD is connected to the RXD pin for external use
6. JP4 is not used currently
NOTE: External RXD pin may be 2.8V, 3.3V or 5V logic and is automatically converted.
QLG2 manual for ;rmware 1.00a 15

3.11 Microcontroller configuration
The 2 x 5 pads near the microcontroller chip, configure the operation of the microcontroller.
These jumpers are “read” by the microcontroller at po er-up in order to determine the
configuration. Thereafter, they are ignored; therefore if a jumper plug is removed (for
example) after po er-up, nothing ill happen until the next time the po er is removed and
applied again to the board.
By default, none of these pads have any connection (no tinned copper traces on the
underside of the board). The nomenclature PA4, PA0 etc is a reference to the port pins of
the microcontroller. PA7, PA6 and PA5 are currently unused.
The operation of these configuration jumpers is:
PA4: Bootloader
JUMPER: Causes the microcontroller to enter the bootloader (see section belo )
OPEN: Causes the microcontroller to run the normal USB to Serial converters
PA : Baud rate
JUMPER: Baud rate is set to 38,400 (suitable for QCX CAT)
OPEN: Baud rate is set to 9,600 (suitable for default GNSS module communication)
Example configuration for CAT control of a QCX-series CW transceiver:
QLG2 manual for ;rmware 1.00a 16

The diagram above sho s an example interface and microcontroller configuration, to use
the USB to Serial converter for connecting a host computer to a QCX-series transceiver for
CAT control. The JP6 jumper must be cut from its default UPPER position, and install a
connection (jumper) at the LOWER position. This selects the external RXD pin as input to
the USB to Serial converter receive signal. Additionally a jumper must be installed at PA0 to
configure the microcontroller USART peripheral for 38400 baud operation to suit QCX.
3.12 Connecting an LCD module
An LCD module may be connected to the QLG2 module directly. The standard 16 x 2
alphanumeric LCD module such as used in the Ultimate3S, VFO, Clock, QCX and QCX+
kits (blue colour) or the QCX-mini (yello /green colour) can be used here; these types of
LCD are available from many vendors. If it is HD44780 compatible (99% are) and has the
ro of 16 pads along the top edge, it ill ork. The kit is not designed to drive display
sizes other than 16 x 2.
Installation of the LCD module is on the UNDER-side of the QLG2 module and is done in
the same ay as on the Ultimate3S, VFO and Clock kits and ith the same components,
namely:
•16 x 2 LCD module, 80 x 36mm HD44780 compatible
•16- ay male pin header connector (soldered ith the short side of the pins to the
underside of the QLG2 board)
•16- ay female pin header connector (soldered to the underside of the LCD module
as sho n)
•4pcs 12mm hex nylon M3-threaded spacer
•8pcs 6mm M3 nylon scre
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Additionally a 22K trimmer resistor is necessary and is installed in the provided position on
the QLG2 board as sho n belo :
On po er-up, the LCD briefly sho s the firm are version of the program file that is held in
the Flash memory of the microcontroller chip, for example 1_00.QG2 (the QG2 extension is
for QLG2, but because it is a FAT16 file system file names are limited to ye olde 8.3
format).
Thereafter a display is sho n such as the one belo . It updates once per second and
sho s time (UT, GMT) on the top ro , and GPS information on the bottom ro .
NOTE: The green LED is just left over from a debugging development session.
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The GPS information display contains five fields as follo s:
1. Validity:
A: Valid fix
V: No valid fix is available yet
2. Nature of fix computation
2D: 2-D fix (requires a minimum of 3 satellites)
3D: 3-D fix (requires a minimum of 4 satellites)
3. f (Fix): the number of satellites used in the position fix computation
4. t (Tracking): the number of satellites being tracked
5. s (SNR): The average signal to noise ratio of the satellites being tracked – higher
numbers indicate stronger signal strength
3.13 QLG2 Commands
QLG2 normally converts all incoming serial data from the USB host, converts it to standard
Serial, and transmits this to the GNSS module (or via the TXD interface pin).
Ho ever, there are also several commands hich you can type into the Terminal Emulator
indo on the host PC, as follo s:
$$QFU immediately causes QLG2 to restart in the bootloader mode (firm are update)
$$VER returns the current firm are version file name, for example, 1_00.QG2
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4. Firmware update procedure
The QLG2 module contains a ne firm are update procedure for STM32-series
microcontrollers, called QFU (QRP Labs Firm are Update) hich provides the follo ing
features:
•Easy – anyone can do the firm are update
•No additional hardware required: only a standard USB A-B cable (or micro-USB
cable if you have installed a micro-USB connector)
•No additional software required: just the standard file manager application that is
already available on any PC
•No drivers: no special drivers need to be installed, the existing drivers on any
modern operating system are used
•Works on any PC Operating System: and in the same ay: Windo s, Linux, Mac
•Secure: firm are files are published on the QRP Labs ebsite and are encrypted
using 256-bit AES encryption technology
Entering bootloader (firmware update) mode:
In the QLG2 there are t o possible ays to initiate a firm are update:
1) Issue the command $$QFU by typing these letters into the host PC Terminal
Emulator connected to QLG2
2) Make a temporary jumper connection as sho n:
The connection can easily be made just ith a small piece of bare tinned copper ire
temporarily inserted in the jumper holes and not soldered; the connection only needs to be
made at the moment of po er-up of the QLG2, hich is hen the microcontroller
configuration jumpers are read and actioned.
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