[Dprglist] Communication between RPi and QTPy

[Thalanayar Muthukumar]

Thanks Chris

Sent from my iPhone

> On Sep 29, 2021, at 9:54 PM, Chris N <netterchris at gmail.com> wrote:
> 
> 
> 
> In a nutshell:
> On the QtPy :
> * program the qtpy using VSCode + PlatformIO + Arduino framework 
> * I usually run VSCode on my Windows/Linux laptop and use the VSCode "remote" feature, but that was not working reliably for this case, so for this I simply run VSCode on the Pi directly and use VNC
> * use the "Adafruit_BNO08x" Arduino library
> * add a 1sec delay at power-up / reset, to allow the virtual serial port to get properly initialized and to give the Pi and QtPy some time to do their virtual serial port handshaking
> * be sure to explicitly reset the bno - i have found that otherwise it sometimes does not work properly on power-up
> * configure the bno085 to report "game rotation vectors" @ 100Hz
> * use polling to get the values from the bno085 (no I/O pin left on the QtPy to use the interrupt signal from the bno085)
> * @ 100Hz, print current time, yaw and the 8 analog readings from the QtPy's analog inputs using Serial.printf() like so: 
> * Serial.printf("%09lu,%+07.3f,%03d,%03d,%03d,%03d,%03d,%03d,%03d,%03d\r\n", t_now, imu_yaw, a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7])
> 
> On the Pi:
> * using python
> * use serial.read()  from the python serial library - with timeout   ( not serial.readline()  - that one does not perform well)
> * parse the comma-separated values (see printf() statement above)  via the scanf function from the scanf python library
> * do some math to compensate for the ~1.5 ... 2.0 degrees worth of offset/error that accumulates for every 360 degrees of rotation.
> 
> I invited you to 2 of my github repos.  romi/qtpy.py   is the code for the Pi,   io_slave_2 is the code for the QtPy itself.
> 
> 
> On Tue, Sep 28, 2021 at 11:01 PM Thalanayar Muthukumar <tnkumar at gmail.com> wrote:
>> Hi Chris,
>> 
>> I also have a QTPy connected to a BNO055 and would like to have the information accessible to the RPi.
>> 
>> It was interesting to hear of the communication you have built between the RPi4 and QTPy.
>> 
>> If you have any pointers on how to accomplish this, will appreciate it. Thanks.
>> 
>> Regards.
>> - Kumar
>> 
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