in python example of GYRO data segmentation fault

mohamed167

i would like to ask a problem that occurs when i run the python code with uses the C++ APIs library

there is a setting called enable high frequency stream when i enable it and then run the python code i can discover the board and connect to it then when i start to get the data i get segmentation fault instead

so what does this enable high frequency stream do and why does the libmetawear give this error and how can i fix it

i am using CentOS with MeaWear CPro and pygatt back end.

Eric

Can you post the full python code you are using along with the firmware revision that your board is currently running?

mohamed167

currently i am using MetaWear CPro boards with firmware 1.2.2

i use it with pygatt back end and the python code i am using is the ACC example code provided with the pymetawear python warper for the C++ APIs with few modifications for storing the data in csv

here is the code it self and the problem is when i set high frequency stream to true and run the code after it connects to the board it gives segmentation fault

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
:mod:`accelerometer`
==================

Created by hbldh <henrik.blidh@nedomkull.com>
Created on 2016-04-10

"""

from __future__ import division
from __future__ import print_function
from __future__ import absolute_import

import time, datetime, csv, pygatt, signal
from datetime import datetime

from pymetawear.discover import select_device
from pymetawear.client import MetaWearClient

address = select_device()
c = MetaWearClient(str(address), 'pygatt', debug=True)
print("New client created: {0}".format(c))

def handler(signum, frame):
    print ("force disconnect")
    c.accelerometer.notifications(None)
    time.sleep(5.0)
    c.disconnect()

signal.signal(signal.SIGTSTP, handler)

def acc_callback(data):
    """Handle a (epoch, (x,y,z)) accelerometer tuple."""
    now = datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%S.%f')
    print("Client, X: {1}, Y: {2}, Z: {3}".format(data[0], *data[1]))

    datastr = ("{1},{2},{3}".format(data[0], *data[1]))
    data="".join(datastr)
    datarow=now+","+data

    with open('acc.csv', 'a') as csvfile:
        writer = csv.writer(csvfile, delimiter=' ',
                            escapechar=' ', quoting=csv.QUOTE_NONE)
        writer.writerow([datarow])

print("Write accelerometer settings...")
c.accelerometer.set_settings(data_rate=50.0, data_range=16.0)
print("Subscribing to accelerometer signal notifications...")
c.accelerometer.high_frequency_stream = False
c.accelerometer.notifications(acc_callback)

while(1):
    time.sleep(10.0)

Eric

High frequency streaming is only available on firmware v1.2.3 and later; update your board's firmware with an Android or iOS device.

Furthermore, pymetawear is a community provided library that layers its own API over the the python wrappers.  Questions pertaining to that library may be better answered by the author.

https://github.com/hbldh/pymetawear/