Questions on uart for pi image

#1

I am trying to communicate over uart, but running into some problems.
i can see that it is pin 8,10 (14 TX ,15 RX) and the following is how I am setup:
/boot/config.txt
enable_uart=1 from raspi-config
ls -l /dev/serial0 links to /dev/ttyAMA0 - this is correct right?

Do i need to disable Bluetooth?
Do i need to do anything to the speed value (ie, change from 250?)
Using Python 3.5

Thoughts?

UPDATE Looks like the answer was in the /boot/config.txt
I enabled the pi3-miniuart-bt

Allow UART and Bluetooth at the same time https://github.com/UbiquityRobotics/ubiquity_main/issue$

dtoverlay=pi3-miniuart-bt

Now the challenge is that on reboot, something is pausing my python.
Sounds strange but I am at a loss…

ubuntu@ubiquityrobot:~$ sudo lsof /dev/serial0
lsof: WARNING: can’t stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
Output information may be incomplete.
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
motor_nod 1685 ubuntu 10u CHR 204,64 0t0 6182 /dev/ttyAMA0
python 2198 ubuntu 6u CHR 204,64 0t0 6182 /dev/ttyAMA0

UPDATE UPDATE
okay… it was my misunderstanding of what that actually means.
This according to the manual should disable Bluetooth and enable UART over 14/15 but what if I wanted to use the GPIO UART and Bluetooth? I might be missing something.

pi3-disable-bt

#2

Are you attempting to communicate with the Magni control board or is this for some unrelated usage in your own project where you are using the Ubiquity Robotics Image?

If on your own then part of the issue would be on our just added support page for users of the image only. Please see how to disable the usage of serial port by Magni which is the default for our image. It may or may not be an issue for you now but is of interest to any user of serial port on our image.

If you find some sort of solution to your problem we may post it on the above page to help others if other users of the image only have this problem.

Mark

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#3

ah…yes. Trying to use the image without the magni-base and I need the UARTS.
I just disabled it based on the instructions but still seems like something is still using it and cannot send or receive over it. I am digging…
If I disable magni-base and reboot, looks like it kills all the topics?
My goal would be to leverage the Nav Stack and send info from the base (it is a sphero RVR and uses UART to communicate with my pi3 b that has ubiuity image running)

#4

I have used this image on a few other of my bots but each has it’s own specific needs.
When I have required more serial ports (often the case due to Raspberry Pi minimal available serial ports) I use USB serial ports available on the cheap on EBay that typically use the Cp210X series of usb to serial chips.

Use this string on EBay: usb to serial port cp2102

Use of them would allow you several serial ports easily with no issue on this image.

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#5

just switched to using a USB to serial converter. Thanks!