Dear all,
I'm trying to use the ParamLogging application
(.../tiny2/tinyos-2.x-contrib/shimmer/apps/ParamLogging) to log
accelerometer and gyro values.
Thanks to Mike I'm able to compile and run it, but when I try to read the
data from the SD card I get weird results.
I tried both the Matlab code in the manual and the python code read_em.py
suggested to read data recorded using JustFATLogging.
Hereby you can see the code that I used:
MATLAB:
fid = fopen('.../../acceltot.bin');
more off
accelx = fread(fid, 'uint16', 4);
L = length(accelx);
t = (0:L-1)/50;
frewind(fid);
fseek(fid,2,'bof');
accely = fread(fid, 'uint16', 4);
frewind(fid);
fseek(fid,4,'bof');
accelz = fread(fid, 'uint16', 4);
frewind(fid);
fseek(fid,6,'bof');
gyrox = fread(fid, 'uint16', 10);
frewind(fid);
fseek(fid,8,'bof');
gyroy = fread(fid, 'uint16', 10);
frewind(fid);
fseek(fid,10,'bof');
gyroz = fread(fid, 'uint16', 10);
figure
subplot(3,1,1); plot(accelx, 'r'); title 'Accel X';
subplot(3,1,2); plot(accely, 'g'); title 'Accel Y';
subplot(3,1,3); plot(accelz, 'b'); title 'Accel Z';
figure
subplot(3,1,1); plot(gyrox, 'r'); title 'Gyro X';
subplot(3,1,2); plot(gyroy, 'g'); title 'Gyro Y';
subplot(3,1,3); plot(gyroz, 'b'); title 'Gyro Z';
Python
#!/usr/bin/python
import os, sys
import array
USAGE_TEXT = """
Usage: read_em.py <datafile>
"""
def usage():
print USAGE_TEXT
sys.exit(-1)
def read_it(filename):
try:
f = open(filename, 'r')
except:
print "can't open %s for read" % filename
sys.exit(-2)
finfo = os.stat(filename)
sz = finfo.st_size
sz = sz / 2
data = array.array('H')
data.fromfile(f, sz)
f.close()
return data
def print_em(data):
t = 0.00
s = len(data)
for i in range(0,s,6):
try:
print "%04.02f\t%d\t%d\t%d\t%d\t%d\t%d" % (t, data[i],
data[i+1], data[i+2],data[3], data[i+4], data[i+5])
except:
print "file has truncated data at index %d" % i
return
t = t + 0.02
def main(argv):
if len(argv) < 1:
usage()
data = read_it(argv[0])
print_em(data)
if __name__ == "__main__":
main(sys.argv[1:])
When I try to plot the data I get almost the same plots for accelerometer
values and gyro values and they look like the charger of a condenser....
I'm wondering if I'm doing some mistake reading the data or the
ParamLogging application has some bugs....did anyone use it before?
Thanks a lot for your help.
Gabriele
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