circuitpython/examples/accellog.py

# log the accelerometer values to a .csv-file on the SD-card

import pyb

accel = pyb.Accel()                                 # create object of accelerometer
blue = pyb.LED(4)                                   # create object of blue LED

log = open('1:/log.csv', 'w')                       # open file to write data - 1:/ ist the SD-card, 0:/ the internal memory
blue.on()                                           # turn on blue LED

for i in range(100):                                # do 100 times (if the board is connected via USB, you can't write longer because the PC tries to open the filesystem which messes up your file.)
        t = pyb.millis()                            # get time since reset
        x, y, z = accel.filtered_xyz()              # get acceleration data
        log.write('{},{},{},{}\n'.format(t,x,y,z))  # write data to file

log.close()                                         # close file
blue.off()                                          # turn off LED