Interfacing the FreeStyle (Mini) Blood Glucose Monitoring System

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Interfacing the FreeStyle (Mini) Blood Glucose Monitoring System

Written by Andreas Böhler

Monday, 08 September 2008 22:39

I recently got my hands on a FreeStyle mini Blood Glucose Monitoring System. Because I'm studying medical engineering, I had to play around with it.
As the FreeStyle has a 3.5mm Stereo-plug for data communication with a computer, I asked Abbott about the cable for studying and in fact they sent me one for free!
So, I quickly searched around and couldn't find ANY Linux-program that could interface a FreeStyle blood glucose monitor.
At the university, we started using Matlab, so I thought: Hey, why not implement this in Matlab? In fact, it was quite easy to read from the Serial port. A professor of mine told me about python, so I also started programming in python. Therefore, you can find code for Matlab and python below.

Python Code

The code below is a very simple python-script that reads from the first serial port and writes the data to a file called freestyle.csv. The data can then be analyzed using e.g. OpenOffice.org Calc.

#!/usr/bin/env python
#####################
# Query FreeSyle Blood Glucose Meter for Memory and write data to CSV file freestyle.csv
#
# (c) 2008 Andreas Boehler
# andy (dot) boehler (at) gmx (dot) at
#
# v0.1 2008/04/02
#
# ChangeLog
#
# v0.1 Initial Release, my very first python program :)
#
#####################


import serial

###################################
# Function to read from FreeStyle #
###################################

def freestyle_read():
	ser = serial.Serial(0, 19200, timeout=1) #Open first serial port
	print 'Port used: ' + ser.portstr  #Print the used port
	ser.write('mem')  #Query FreeStyle
	line = ''
	line_vector=[]

	while line.find('END') == -1:  #Read from FreeStyle
		line = ser.readline()
		line_vector.append(line)

	ser.close()  #Close port

	return line_vector

###########################################################
# Function to convert line to data and eliminate newlines #
###########################################################

def str2data(line): #Convert line to data, eliminating \r\n
	str = line[0:len(line)-2]
	data = str.split()
	return data

#############################
# Main program starts below #
#############################

line_vector = freestyle_read() #Read from the meter

num_entries = int(line_vector[4])
print 'Number of records found: ' + str(num_entries)

data=[]

for i in range(num_entries):  #Eliminate \r\n from Data and append it to list
	line_data = str2data(line_vector[i+6])
	del line_data[len(line_data)-2:len(line_data)]
	data.append(line_data) 

#print data
try:
	fp = file('freestyle.csv', 'w')
except:
	fp = None
	print 'File could not be opened for writing (Permission?)'

if fp:
	for i in range(num_entries): # Create CSV string from data
		str = data[i]
		#Append data to new string
		out_str = str[0] + ';' + str[1] + ' ' + str[2] + ' ' + str[3] + ';' + str[4] + '\n'

		fp.writelines(out_str) #Write string to file

	#Close file and delete object

fp.close()
del fp

Matlab Code

The Matlab code is even easier and simpler: It just queries the first serial port, reads from the meter and returns a vector containing each line as a string.

%% string_vector = freestyle_read(portname)
%        Fetches FreeStyle-Data from given Port
%
% (c)2008 Andreas Boehler
% andy (dot) boehler (at) gmx (dot) at
%
% This function opens a serial port given by portname and queries the
% hopefully connected FreeStyle-device for its memory. The whole memory is
% then returned.
%
% Tested on FreeStyle mini!
%
% v0.1 2008/04/02
%
% ChangeLog
%
% v0.1 Initial Release
%
%%%%%%%%%%%%%%%%%%%%

%% string_vector = freestyle_read(portname) starts below

function string_vector = freestyle_read(portname)

serial_object = serial(portname); % Create serial object and set parameters
set(serial_object,'BaudRate',19200);

fopen(serial_object); % Open our port and query FreeStyle
fprintf(serial_object,'mem');

ii = 1; % Set initial values
read_string = '';
string_vector = {};

while (isempty(strfind(read_string,'END'))); % Fetch data
    read_string = fscanf(serial_object);
    string_vector{ii} = read_string;
    ii = ii+1;
end
fclose(serial_object); % Close the port

%% EOF