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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Solved-ish... Help: GPS seem to only work on one USB port now

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Hello,

I have setup the GPSD and the GPS unit was working fine for a test.
Then today, I moved it to a different USB port because I realized I plugged it into a USB3 port on the RPi so I thought I’d move it over to a different port. But, GPSD never seems to find it now on the new port (the port I’d prefer to use). The good news is, it still works on the original port I plugged it into but I would like to move ports.
How do I move the GPS to a new port?

All help would be greatly appreciated.

Thanks,
Brett
3 years 9 months ago #56071

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Just replying to see if anyone has any thoughts here.

Help greatly appreciated!
3 years 9 months ago #56177

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Hello all,

I wanted to let you know that I found out how to get it working. Here is what I seem to have to do:
1) Un-plug the GPS un-plugged before I power on the system.
2) Power on the system
3) Start up the GPSD service (if not set to start automatically)
4) Plug in the GPS

All of that seems to get it to work well.
Not sure if that is how it is supposed to be - but hey! Super happy it is working.

Brett
3 years 8 months ago #56193

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Hello,

Fantastic news! But... let’s start with what is connecting to this RPI4B? GPS units require a dedicated ACM (Asynchronous Communication Management) port. Mounts require a dedicated management port.

Every RPI version has limits. ACM ports are limited. The ttyAMA0 and ttyS0 are dedicated to the keyboard and Bluetooth ACM timer. This leaves ttyACM0 as the first ACM port free to hungry AC USB types. Other USB types are passive attachments. They share any number of tty types the OS has. Hubs further extend the PI. Remember, the PI is limited.

What could be happening is last-man-sitting game. ACM0 is the free one. The GPS device is fast. It grabbed the only ACM port available. The previous session had another ACM need faster which grabbed the ACM before the GPS could. A power recycle reset the device race and the GPS won.

Reading logs is a key need to finding the culprits fighting for the lone ACM port. Open a terminal window. With your setup connected, type lsusb and hit enter. Take a screen shot of the output. The information is very pertinent to how to consistently help the RPI to manage our needs.

From here, UDEV is our friend and has an area of rules stored specifically on the PI labeled /lib/udev/rules.d. We can create and modify rules under SUDO. File Manager viewing gives read only viewing. 99 is where I like to keep my needs. I also create unique names. This area is under RPI management control. Keep backup copies of specific needs store safe. What RPI gives, they can take away. For awhile, udev was in two places. Now, it is in one place.

At the present, I have only to needs, GPS and EQMOUNT. Mounts are usually ACM types. IP is a different need, but Parallel. Hence, the need to manage the ACM fight. The PI way to dedicate ACM types is through ttyACM. The rules identify to PI how to divvy up the ACM controller onboard. This controller isn’t infinite as in ttyACMN were N > 5.

So, be prudent. Walk carefully. Figure out how what is needed and manage the need through rules.

Here is my example. I have 7 USB needs. I use two 4 port USB 3.0 hubs. One hub manages 3 CCD and joystick. One hub manages this order: EQMOUNT, GPSD, and a 32GB stick. This works when I mange my ACM needs. My CCD needs are PoleMaster, QHY5LII, and a ZWO 120mm mini. One guides, the other is taking pictures. That is my plan. Let us know your results.
3 years 8 months ago #56209

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