Multiple MetaMotionC connection Error

Aubrey_1

Good day
Ive managed to connect to one sensor and steam euler angles. I'm currently trying to connect the second sensor...I get an error
"Segmentation fault" when i run the "read()" in my code.

please see code for reference and help out where possible.

usage: python scan_connect.py

from future import print_function
from mbientlab.metawear import MetaWear
from mbientlab.metawear.cbindings import *
from mbientlab.warble import *
from mbientlab.metawear import *

from datetime import *
import json, csv
import sys,platform,six
from time import sleep

try:
from StringIO import StringIO

except ImportError:

from io import StringIO

I hard coded the address in, just not displaying it here

device = MetaWear("XX:E2:XX:C5:60:XX")
device.connect()
sensor_1 = device.board

output1= StringIO()

'''
device = MetaWear("C6:XX:XX:27:XX:04")
device.connect()
sensor_2 = device.board
output2 = StringIO()
'''

buf = [100]

_______________________________________________________________________

def disconnectS(b):

libmetawear.mbl_mw_sensor_fusion_stop(sensor_1)
libmetawear.mbl_mw_sensor_fusion_clear_enabled_mask(sensor_1)
libmetawear.mbl_mw_datasignal_unsubscribe(euler_signal)
device.disconnect()
print ('disconnected')
sleep(1)

_______________________________________________________________________

def csvLog(but):

fin = open("log.csv","rt")
updateData = fin.read() 
oldData = updateData
updateData = updateData.replace(updateData,buf[0:89])
fin.close()

updateData = updateData.replace(" ","")
updateData = updateData.replace("{","")
updateData = updateData.replace("}"," ")
updateData = updateData.replace(" ","")
updateData = updateData.replace("epoch:","")
updateData = updateData.replace("heading:","")
updateData = updateData.replace("pitch","")
updateData = updateData.replace("roll:","")
updateData = updateData.replace("yaw:","")
updateData = updateData.replace(":","")

fin = open("log.csv","wt")
fin.write(updateData)
fin.close()

fin = open("log.csv","rt")
updateData = fin.read()
fin.close()

_______________________________________________________________________

def swtichOnOff(b):

 libmetawear.mbl_mw_sensor_fusion_start(b)
 sleep(0.3)
 libmetawear.mbl_mw_sensor_fusion_stop(b)

def read(b):

global euler_signal

euler_signal = libmetawear.mbl_mw_sensor_fusion_get_data_signal(b, SensorFusionData.EULER_ANGLE)    
euler_callback = FnVoid_VoidP_DataP(lambda context, data: output1.write("epoch:%s,%s\n" % (data.contents.epoch, parse_value(data))))

libmetawear.mbl_mw_datasignal_subscribe(euler_signal, None, euler_callback)
libmetawear.mbl_mw_sensor_fusion_enable_data(b, SensorFusionData.EULER_ANGLE)
libmetawear.mbl_mw_sensor_fusion_set_mode(b, SensorFusionMode.NDOF)
libmetawear.mbl_mw_sensor_fusion_write_config(b)

_______________________________________________________________________

try:
#ERRRRRRRRRRRROR

read(sensor_1)

while True:

    swtichOnOff(sensor_1)               
    buf = str(output1.getvalue())
    output1 = StringIO()

    csvLog(buf)

    with open('log.csv') as csvfile:

        readcsv = csv.reader(csvfile,delimiter=',')
        for row in readcsv:
            timeStamp = row[0]
            pitch = row[2]
            roll = row[3]
            yaw = row[4]
            break

    print (pitch,roll,yaw)
disconnectS(sensor_1)

except:

disconnectS(sensor_1)

_______________________________________________________________________

Laura

format your code. we cannot read this.

Aubrey_1

usage: python scan_connect.py

from future import print_function
from mbientlab.metawear import MetaWear
from mbientlab.metawear.cbindings import *
from mbientlab.warble import *
from mbientlab.metawear import *
from datetime import *
import json, csv
import sys,platform,six
from time import sleep
try:
from StringIO import StringIO
except ImportError:
from io import StringIO

I hard coded the address in, just not displaying it here

device = MetaWear("XX:E2:XX:C5:60:AA")
device.connect()
device1 = MetaWear("XX:81:2C:27:XX:04")
device1.connect()
sensor_1 = device.board
sensor_2 = device2.board
output = StringIO()
buf = [100]

_______________________________________________________________________

def disconnectS(b):
libmetawear.mbl_mw_sensor_fusion_stop(sensor_1)
libmetawear.mbl_mw_sensor_fusion_clear_enabled_mask(sensor_1)
libmetawear.mbl_mw_datasignal_unsubscribe(sensor_1_signal)
device.disconnect()
print ('disconnected')
sleep(1)

_______________________________________________________________________

def csvLog():
fin = open("log.csv","rt")
updateData = fin.read()
oldData = updateData
updateData = updateData.replace(updateData,buf[0:89])
fin.close()
updateData = updateData.replace(" ","")
updateData = updateData.replace("{","")
updateData = updateData.replace("}"," ")
updateData = updateData.replace(" ","")
updateData = updateData.replace("epoch:","")
updateData = updateData.replace("heading:","")
updateData = updateData.replace("pitch","")
updateData = updateData.replace("roll:","")
updateData = updateData.replace("yaw:","")
updateData = updateData.replace(":","")
fin = open("log.csv","wt")
fin.write(updateData)
fin.close()
fin = open("log.csv","rt")
updateData = fin.read()
fin.close()

_______________________________________________________________________

def swtichOnOff(b):
libmetawear.mbl_mw_sensor_fusion_start(b)
sleep(0.3)
libmetawear.mbl_mw_sensor_fusion_stop(b)

_______________________________________________________________________

try:
sensor_1_signal = libmetawear.mbl_mw_sensor_fusion_get_data_signal(sensor_1, SensorFusionData.EULER_ANGLE)
euler_callback = FnVoid_VoidP_DataP(lambda context, data: output.write("epoch:%s,%s\n" % (data.contents.epoch, parse_value(data))))
libmetawear.mbl_mw_datasignal_subscribe(sensor_1_signal, None, euler_callback)
libmetawear.mbl_mw_sensor_fusion_enable_data(sensor_1, SensorFusionData.EULER_ANGLE)
libmetawear.mbl_mw_sensor_fusion_set_mode(sensor_1, SensorFusionMode.NDOF)
libmetawear.mbl_mw_sensor_fusion_write_config(sensor_1)
while True:
swtichOnOff(sensor_1)
buf = str(output.getvalue())
output = StringIO()
csvLog()
with open('log.csv') as csvfile:
readcsv = csv.reader(csvfile,delimiter=',')
for row in readcsv:
timeStamp = row[0]
pitch = row[2]
roll = row[3]
yaw = row[4]
break
print (pitch,roll,yaw)
disconnectS(sensor_1)
except:
disconnectS(sensor_1)

_______________________________________________________________________

Aubrey_1

@Laura said:
format your code. we cannot read this.

Does that help?

Laura

its worse, maybe include it in a file?

Aubrey_1

The moment i paste it on the forum it "reformat" cant attache a file either

Laura

You could link to a file...

Aubrey_1

@Laura said:
You could link to a file...

see below code:

When i run the code a get a stream of the euler angles. See below for results.

line 26. where im capturing the data into the "euler_callback" variable and print the type of variable on line 33 the result comes out as a . while at first i thought its a dictionary.

I would like to extract the data i get( timestamp,heading,pitch,roll,yaw) into seperate variable that i can use for my application

EG.

while True:
sleep(1)
x = euler_callback['heading']
print (x)

Laura

Please get more comfortable using Python. Clearly this is simply a case of python dev limitations and not a bug with our SDK.
Also read our tutorial sections on the data formats.

Aubrey_1

@Laura said:
Please get more comfortable using Python. Clearly this is simply a case of python dev limitations and not a bug with our SDK.
Also read our tutorial sections on the data formats.

Im not saying its a but at all i've been trying all possible methods i know of and nothing has worked so far. if you would kindly lead me in the right direction

Aubrey_1

The best method ive tried was to log the angles on a csv file but that reduced the the number of sambles i could get to 300ms which slowed down my system drastically, I've alos tried to use string IOs to print the data into a var, which worked but constantly had to stop and start the sensor connection with a dealy of (0.3sec) in between which reduced the number of samples im reading

Laura

I think you should read the function: "parse_value" and see how it extracts the data from the callback (from the sensor bluetooth stream). data is a pointer to the sensor data and it needs to be parsed correctly.

Please see some examples here: https://github.com/mbientlab/MetaWear-SDK-Python/search?p=1&q=parse_value&unscoped_q=parse_value

Aubrey_1

@Laura said:
I think you should read the function: "parse_value" and see how it extracts the data from the callback (from the sensor bluetooth stream). data is a pointer to the sensor data and it needs to be parsed correctly.

Please see some examples here: https://github.com/mbientlab/MetaWear-SDK-Python/search?p=1&q=parse_value&unscoped_q=parse_value

Hi, thank you so much !

Eric

@Aubrey_1 said:
line 26. where im capturing the data into the "euler_callback" variable and print the type of variable on line 33 the result comes out as a . while at first i thought its a dictionary.

I would like to extract the data i get( timestamp,heading,pitch,roll,yaw) into seperate variable that i can use for my application

EG.

while True:
sleep(1)
x = euler_callback['heading']
print (x)

Couple of things...

euler_callback is a callback function, as you have noted; it doesn't return anything. All the post processing needs to be done in the callback function so your while loop is nonsensical.

As Laura noted, parse_value extracts the actual value from the data pointer. The code in calibrate.py is somewhat similar to what you are trying to do.

Lastly, the Python code bridges into the C side with the ctypes module. Reading the docs on that module will help better understand the sample code.
https://docs.python.org/3/library/ctypes.html

Aubrey_1

@Eric said:

@Aubrey_1 said:
line 26. where im capturing the data into the "euler_callback" variable and print the type of variable on line 33 the result comes out as a . while at first i thought its a dictionary.

I would like to extract the data i get( timestamp,heading,pitch,roll,yaw) into seperate variable that i can use for my application

EG.

while True:
sleep(1)
x = euler_callback['heading']
print (x)

Couple of things...

euler_callback is a callback function, as you have noted; it doesn't return anything. All the post processing needs to be done in the callback function so your while loop is nonsensical.

As Laura noted, parse_value extracts the actual value from the data pointer. The code in calibrate.py is somewhat similar to what you are trying to do.

Lastly, the Python code bridges into the C side with the ctypes module. Reading the docs on that module will help better understand the sample code.
https://docs.python.org/3/library/ctypes.html

Appreciate the responce Eric currently working through the solution.

Aubrey_1

@Eric & @Laura

I would like to say thank you for your assistance with regard to the above issue i had. with you assistance i manged to figure out how save the variables as my application requires. Thank you for taking the time to help me.

Aubrey_1

Hi @Laura & @Eric

I'm getting the following two errors when i run the peice of code in the attached file (text.txt)
Error 1:

error 1586435361.351481: Error on line: 296 (src/blestatemachine.cc): Operation now in progress
*** buffer overflow detected ***: python3 terminated
Aborted

Error 2:

Failed to write value to characteristic(Error trying to issue command mid state)

See attached images for further clarity

These errors occur occasionally as most of the time i do log the data, but somewhere at a curtaion point the logs stop and when i quit the program the Error 2 occurs, while Error 1 occurs when i try to reconnect

Your assistance is highly appreciated