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 power 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 wires that will be described
in the next section. Note that 2.8V logic will be compatible with 3.3V systems, without issue.
From left to right:
•
Power supply ground.
•
1pps: 1 Pulse Per Second output from the GNSS module; by default this pulse is 0.1
seconds wide and it is sent once per second. By default, the voltage level is 5V
which is suitable for use with 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, which is suitable for use with 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; when the jumper wires 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, which 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: Power supply positive. It is nominally 5V, but in fact you could power the QLG2
module from any positive supply voltage in the range 3.3V to 6.0V, and the onboard
voltage regulator will provide 3.3V to the GNSS module which 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 will
be at that different supply voltage, not 5.0V.
QLG2 manual for firmware 1.00a
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