si5351_sweeper.ino

#include "si5351.h"
#include "Wire.h"
 
Si5351 si5351;
long a;
int inData;
 
void setup()
{
  // Start serial and initialize the Si5351
  Serial.begin(57600);
  si5351.init(SI5351_CRYSTAL_LOAD_8PF);
  si5351.set_correction(8);
}
 
void loop()
{
  
  while (Serial.available() > 0)   // see if incoming serial data:
  { 
    inData = Serial.read();  // read oldest byte in serial buffer:
  
    // Serial.println("Test of serial");
    if (inData == 'A')
    {
      a = Serial.parseInt();
      Serial.println(a);
          
      // Set CLK0
      si5351.set_freq(a * 100ULL, 0, SI5351_CLK0);
    }
  }
}

sweep.py

import usbtmc
import serial
import time
import sys
import math

lower_freq = 500000
upper_freq = 160050000
freq_step = 500000
	
# Arduino serial dev paramaters
DEVICE = '/dev/ttyACM0'
BAUD = 57600

# Open the DSA815 and config for reading frequency
sa = usbtmc.Instrument(0x1ab1, 0x0960)

# Open serial port
try:
	ser = serial.Serial(port=DEVICE, baudrate=BAUD, timeout=2)
except:
	print 'Cannot open serial port'
	sys.exit(0)
	
# Preset
sa.write(":SYST:PRES")
time.sleep(2)

sa.write(":FREQuency:SPAN 100000")
time.sleep(1)
	
file = open('sweep.csv', 'wt')
file.write('Frequency (Hz),Amplitude (dBm)\n')

# Main control loop
for freq in range(lower_freq, upper_freq, freq_step):
	# Set the Si5351A
	ser.write('A' + str(freq))
	time.sleep(5)
	
	# Peak Search
	sa.write(":FREQuency:CENTER " + str(freq))
	time.sleep(1)
	
	sa.write(":CALCulate:MARKer1:MAXimum:MAX")
	time.sleep(1)
	
	# Get the amplitude
	amplitude = sa.ask(":CALCulate:MARKer1:Y?")
	
	# Print it out in comma delimeted format
	output = '{},{}'.format(freq, amplitude)
	print output
	file.write(output + '\n')
	
file.close()