Hi again Gabriele,
A correction to your MATLAB code that I forgot to mention - you must skip 10 bytes when you read the accelx, accely and accelz values, not 4 bytes. This, along with my previous email should solve your problem. Best regards, Niamh _____ From: [email protected] [mailto:[email protected]] On Behalf Of Niamh O'Mahony Sent: 03 October 2012 16:33 To: 'Gabriele Spina'; [email protected] Subject: Re: [Shimmer-users] ParamLogging Hi Gabriele, Your code looks fine - I've tested the MATLAB version with data output by ParamLogging and it's giving me meaningful results. I suggest you check that you have saved the sample.cfg file in the top level directory of the SD card on the shimmer and make sure that you have both the accelerometer and gyroscope selected. (The example sample.cfg file from the ParamLogging directory selects accelerometer and magnetometer by default so this will have to be changed accordingly.) If ParamLogging does not find the sample.cfg file in the top level directory of the SD card it should briefly flash the red LED in warning and, then, default to logging accelerometer data only. Also, a word of caution - if the magnetometer is selected in sample.cfg but a magnetometer daughtercard is not present, datalogging will fail and the shimmer will need to be reset. I hope this helps. Best regards, Niamh _____ From: [email protected] [mailto:[email protected]] On Behalf Of Gabriele Spina Sent: 03 October 2012 14:09 To: [email protected] Subject: [Shimmer-users] ParamLogging 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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