marvelmind_c fails (often), advice?

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Joined: Fri Feb 08, 2019 10:20 pm

marvelmind_c fails (often), advice?

Postby tobor » Fri Feb 08, 2019 10:40 pm


After hours and hours of struggling to find a solution and being stumped at the behavior of multiple hedgehogs... I am reaching out.

Reliably sent Marvel Mind data to a Raspberry Pi 3.

- I am using the latest dashboard on Windows.
- I am using the latest firmware on the sensors themselves (no update complaints from the Dashboard)
- Hedgehogs are connected to Raspberry Pi 3s

- Sometimes the sensors show up in the dashboard, but marvelmind_c fails to show readings though it can open up a port.
(I've tried all ports).
- Sometimes the sensors don't show up on the dashboard at all (though nothing has changed from day to day).
- Sometimes the beacons move about the x-y plane when unfreezing the submap.

Before you ask:
Yes the sensors are on, and the DFU switch is off.
The cables are fine.
I've checked all ttyA* ports using marvelmind_c and cat said port.
The baud rate is set to 9600.

Please let me know if there is anything you can do.

Pics are in the Attachments

Posts: 243
Joined: Sat Feb 06, 2016 4:03 pm

Re: marvelmind_c fails (often), advice?

Postby smoker77 » Sat Feb 09, 2019 12:15 am


1. What is the distance between modem and beacons?
Small distance between beacons (except hedgehog 2) leads me to guess that all these beacons are placed on the same table with modem.
But when distance between modem and beacons is low, RSSI (radio signal strength) may be too high and modem will not see beacons via radio.
We recommend distance between modem and beacons at least 1...2 meters.
Also, note when you connect hedgehog to Raspberry via USB cable, this cable works as additional antenna and increases RSSI even more.

2. Have you achieved a good tracking of hedgehogs in dashboard?
Your map is pretty small in size (distance between stationary beacons is small).
Small base between stationary beacons may cause problems in tracking.
When hedgehog is not tracking, it doesn't output its location to serial port.

3. Make sure you are opening correct port on Raspberry.
Disconnect hedgehog from Raspberry and check list of the ports: ls /dev/ttyACM*
Then connect hedgehog to Raspberry and check the list again.
New appeared port is the port of hedgehog (note the port may appear after several seconds after connecting hedgehog).
If you not found hedgehog in /dev/ttyACM*, try ls /dev/ttyUSB*

Seems strange you are not get /dev/ttyACM0. Normally, Raspberry starts to enumerate devices from this port.
May be you have the /dev/ttyACM0 port, but have no access rights for it.
If so, try: sudo chmod 0777 /dev/ttyACM0

Some notes:
- /dev/ttyAMA0 is UART serial port on GPIO pins of Raspberry. If you connect hedgehog via USB, you not need to check /dev/ttyAMA0
- Baud rate setting does not affect communication via USB. This setting is useful only for UART communication

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