QCX assembly Rev 1.08
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The optional GPS interface is provided by a 4-pin header at the bottom right of the board, next to
the 3.5mm socket for the keyer. The pinout of the 4-pin header exactly matches the one on the
QRP Labs Ultimate3S QRSS/WSPR transmitter kit, and the QRP Labs QLG1 GPS receiver kit.
This makes connecting the radio to the QLG1 GPS kit very easy, if you wish. However other GPS
modules could also be used. The following requirements of the GPS module must be met:
•
Positive-going (leading edge) 1 pulse per second signal with a reasonable pulse width
–
e.g. some older GPS module have a 1us pulse and this will not be long enough. The QLG1
GPS receiver provides a 100ms (0.1s) duration pulse, though shorter pulses would also
work.
•
9,600 baud serial data sending standard NMEA 0183 GPS sentences
•
“TTL” voltage levels i.e. 0V “low” and 5V “high” (or at least, below 1.5V and above 3.5V)
The 1pps and Serial data signals from the GPS are connected via 1K resistors, to the “dit” and
“dah” inputs to the microcontroller. The GPS is therefore wired directly in parallel with the paddle.
The GPS may not be used at the same time as the paddle. This would cause the transmitter to be
keyed by the 1pps and serial data signals. The 1K resistors protect the GPS outputs in case the
paddles or onboard microswitch “key” inadvertently ground them.
The ATmega328P has a USART serial data peripheral. However, the pin assignments were
already made, so far down the design process, at the time the GPS receiver option was included.
Furthermore, the I/O pin availability was already scarce. So, the two GPS signals share the same
I/O as the paddle inputs. A software-emulated USART peripheral module now reads the GPS
serial data, at 9600 baud.
5.15
In Circuit Programming (ISP) interface
A 2 x 3-pin header is installed on the PCB to facilitate In
Circuit Programming (ISP) of the ATmega328P microcontroller
in future, if new firmware versions become available.
Firmware updates can be done with a simple USBISP AVR
programmer available from eBay for under $2 including
international shipping. The 2 x 3-pin header pinout matches
the standard AVR programmer cables.
The ISP interface uses the same I/O pins as the GPS interface and the Paddle. When upgrading
the firmware, be sure to disconnect the GPS (if you had one connected). And do not press any
paddle key while doing the firmware update!
5.16
Test Equipment
The built-in test and alignment equipment is a really nice feature of this CW transceiver kit.
Содержание QCX 5W CW
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