10
the ProgRock PCB, then solder them. This way, the Synth module will hold the sockets in perfect
alignment while you solder them.
7)
Fit a 12-way pin header
The ProgRock kit includes a 16-pin header. You can
snap away 4 pins, to create a 12-pin header, and install
this in the PCB’s external connection pad holes, along
the bottom edge of the board.
This is OPTIONAL. You might find it easier and prefer to
solder your wires directly into these holes. But some
people prefer the header pins, so that connectors can be
plugged on. Some people prefer to solder wires directly
to the header pins, which are easier to repair if wires break, than cleaning out and re-using holes on the
PCB. It’s up to you!
The photograph (above right) shows the 12-pin header installed on ProgRock.
8)
Test the voltage regulator and noise filter circuits
Again assuming you are using the recommended power supply option (refer to section 4.3), it is a REALLY
good idea to test the voltages now with a digital volt meter (DVM) before plugging in the microcontroller
IC1, or the Si5351A Synth module. IC1 will be damaged if the supply voltage exceeds 5V and the Si5351A
requires 3.3V supply (3.5V as supplied here, is fine). It’s best to make sure the voltages are correct now,
before frying any of these ICs!
To test the voltage regulator and noise filter, apply the supply voltage to the Gnd and +Vin pins. I
recommend a voltage in the range 7-12V. You should then be able to m5V and +3.5V at the
points indicated in the diagram below. You could use the spare 4-pin header section, inserted into the 10-
way header socket, to provide a pin to touch with the DVM probe for the measurement. Measure the
voltages between the indicated points, and ground. They should measure around 5V and 3.5V respectively
(within 5%).
If there is any problem with the
measured voltages then you have GOT
to investigate and find the problem
before going any further!
