The SigTest, short for signal test, is a test program that can be used for evaluating the Si5351A. There is a simple textual Man Machine Interface (MMI) via the USB port.

SigTest does not rely on GPS signals and frequencies generated are therefore not GPS calibrated. The reason is that for testing purposes you do not want the Si5351A to change frequency, because the reference frequency was changed, behind your back.

The optional SigTest LCD.

Man Machine Interface (MMI)

The MMI is done via the USB port, 9600 Baud, 8 bits, no parity and one stop bit, using a terminal program (e.g. Arduino IDE Serial Monitor, Termite Terminal (Windows), CuteCom (Linux) or Terminal (Mac OS)). Please connect the RFzero via a USB B cable to your computer and connect the terminal program to the right COM port in the terminal program. The RFzero identifies itself as an Arduino Zero (Windows Device Manager).

If you don’t see the RFzero> prompts please press the enter key. When you want to execute a command you don’t have to enter the RFzero> prompt but only the command and parameters after the >.

All input to the RFzero must be in lowercase.

To see the available commands please enter a question mark at the RFzero prompt and press the <Enter> key.

RFzero> ?

The most common commands are

wr freq FREQ

to set the frequency in Hz where FREQ is from 2605 Hz to 300 MHz.

wr rf on

to switch the RF on (CLK0 and CLK1).

wr rf off

to switch the RF off (CLK0 and CLK1).

wr rfc CURRENT

to set the RF output current where CURRENT 2, 4, 6 or 8 mA.

wr fref FREQ

to set the reference frequency used for the math.

rd fref

to read the reference frequency. Not measured!

wr ref on

to switch the reference frequency on (CLK2).

wr ref off

to switch the reference frequency off (CLK2).

wr refc CURRENT

to set the reference frequency output current where CURRENT 2, 4, 6 or 8 mA.


to write the VALUE (hex) to the register at ADDR (dec).

wr abcdr A B C D R

to write the A, B, C, D and R values to the FMD, OMD and R.

wr fmd VALUE0 .. VALUE7

to write the VALUEs (hex) to the FMD registers in the PLL.

wr omd VALUE0 .. VALUE7

to write the VALUEs (hex) to the OMD registers.

rd reg ADDR

to read the value (hex) at the register ADDR (dec).

rd regs

to read registers 26-33 and 42-49/50-57.

wr 2727

sets both RF and reference frequency to 27 MHz and RF on. Then measure the RF frequency and enter the frequency using the wr fref FREQ command. Then frequencies are aligned.