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Ensure that the Si5351A synthesiser module is inserted the correct way round as shown in the
photograph. The Low Pass Filter kit module should be plugged in with the "Out" legend aligned next to the
RF Output connector of the main PCB (see photo).
Important!
Upon power-up, you will need to adjust the contrast potentiometer R1 to view the LCD
properly. Turn it fully clockwise to start with (before applying power). Then turn it gradually
anticlockwise until the displayed text looks correct.
with a) fully clockwise; b) fully anti-clockwise; c) adjusted perfectly. When adjusted perfectly, you will see
"Diagnostic Mode" message on the screen.
When you see "Diagnostic Mode" it means all is well
with the processor and the LCD communication.
When you press the left button, diagnostic mode will
be cleared. Then you should see the flash screen. If
the Si5351A module is correctly built and inserted,
the firmware will recognise it. The text in the splash
screen will say "Ultimate3S". The "S" is important, it
signifies that the Si5351A has been correctly
detected.
If you cannot see any text on the screen even after adjusting the contrast setting, you have a problem.
Please refer to the "Troubleshooting" page on the U3S website (see resources section below).
4. Hardware Options
4.1 Explanation of connections
The table to the right details the purpose of
the connection points around the right-
hand and bottom edges of the PCB. The
pin-spacing is 0.1-inches and a suitable
connector could be used if desired. These
are further described in the following
sections.
Note that the cluster of connections at the
left board edge are for fitting the connector
to the relay-switched LPF board kit. They
can be ignored for now.
Connections A0, A1, A2 and A4 allow options concerning the LCD backlight, as described below. Typically
you should connect A0 and A3, this enables the software controlled backlight control.
The series of photographs below show the display
Label
Group
Description
5V
GPS
+5V supply to GPS module
Gnd
GPS
Ground connection to GPS module
RxD
GPS
Serial data input from GPS module
Pps
GPS
1 pulse per second input from GPS module
R
Future
No connection – for future enhancements
S2
Buttons
Optional external button S2, switch to Gnd
Gnd
Buttons
Ground for optional external buttons
S1
Buttons
Optional external button S1, switch to Gnd
Clk2
Signal
Clk2 Si5351A output, 3.3V p-p squarewave
Clk1
Signal
Clk1 Si5351A output, 3.3V p-p squarewave
Clk0
Signal
Clk0 Si5351A output, 3.3V p-p squarewave
Gnd
Power
Ground connection to Power supply
Heat
Power
+5V heater for OCXO/Si5351A module option
+5V
Power
+5V power supply
+PA
Power
PA power supply – may be connected to +5V
Key
Control
"Keying" output: high during transmit
Gnd
RF
Ground for RF output
RF
RF
RF output
9
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