Wipy 2.0 and save data on my pc, not in flash memory

[VFlorio94]

@robert-hh Thank you, I didn't see your comment before. At the end I am succeded in a similar way, now i'll try also yours
thank you very much

[robert-hh]

@vflorio94 Shortened version, not easy to read:

with open("file.txt", "r") as f:
    list = f.readlines()
    # now you have a list of one string per line
    for index, item in enumerate(list):
        list[index] = [float(el) for el in item.strip("[]\n ").split(",")]
        # now list is a list of lists with numeric values
        # accessible with list[i][j]

[VFlorio94]

@robert-hh the data now are like this

348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000 ,348.750000
<class 'str'>

so i do:

f= open("/sd/dat.txt", "r").read()
f.close()
f1 = f.split(',')
g = []
for i in range(1, len(f1)):
    h = float(f1[i])
    g.append(h)

[robert-hh]

Usign a generator instead of the loop, it can be written e.g. like:

with open("data.txt", "r") as f:
    line = f.read()
    # now you have a list of one string per line
    g = [float(el) for el in line.strip().split(",")]

or even shorter as

with open("data.txt", "r") as f:
    g = [float(el) for el in  f.read().strip().split(",")]

The last expression in the bracket is a little bit cryptic, to be read from left to right as:

• read the line
• strip of leading and trailing whitespace
• split it at , into a list of numeric strings, which is the fed into the generator expression.

[VFlorio94]

@robert-hh thank you, all the code that you wrote run correctly. I understand also your explanation.
thank you a lot !!

[robert-hh]

@vflorio94 A simpler way to store and load is using the ujson module. So if you have a list of values like g, write it with:

import ujson
with open("data.txt", "w") as f:
    ujson.dump(g, f)

and read it back with:

with open("data.txt", "r") as f:
    g = ujson.load(f)

In the micropython.lib, there is also the a pickle module.https://github.com/micropython/micropython-lib/tree/master/pickle

[VFlorio94]

@robert-hh Thank you.
unfortunately I have a new problem with wipy and I2C .

In the library for I2C if i set baudrate to 100k it doesn't work.
but in the data sheet of IMU it is written that it can work with a baudrate with a maximum of 400k.
the error is this one:

  File "/flash/lib_imu.py", line 382, in get_euler
  File "/flash/lib_imu.py", line 318, in read_vector
OSError: I2C bus error

I don't know how i can solve this bus error. Do you have an idea about this topic?

[robert-hh]

@vflorio94 Does it work at lower baud rates? if yes, then maybe the pull-up resistors are missing. The SDA and SCL lines must have a pull-up resistor in the range of 4.7 kOhm. Sometimes they are built on the board, sometimes not. The ESP32 has internal pull-up resistors at about 30 kOhm, which is good for lower baud rates.

[VFlorio94]

@robert-hh It works at lower baudrate like 10K, 15K but for value higher then 20K it doesn't work.

[robert-hh]

@vflorio94 Which BN055 module are you using, and how long are the connecting wires?

[VFlorio94]

@robert-hh I use Fusion mode and operating mode: NDOF.
The connecting wires are about 60 cm.
I have to use two I2C and collect data and wrote on a file with a sample rate of 50 Hz.
But if I set a time.sleep(0.2) that I think means 50Hz, from a sample to another it has a big delay.
So i try to increase baudrate as I tell you before.

[robert-hh]

@robert-hh said in Wipy 2.0 and save data on my pc, not in flash memory:

Which BN055 module

I was asking about the vendor and make of the BNO055 board.