Hi Everyone.

I'm a new user of Kstars/EKOS using astroberry server and I have to say I am very impressed so far. I bought a RPI 4b 4Gb this week and already have it set up in the observatory with a USB wifi dongle providing the extra range to the router in the house. I'm VNC'ing in from a laptop in the house.

All seems to be panning out nicely but I have noticed several occassions today where my mount will disconnect - usually while slewing. Looking at dmesg output it seems the FTDI driver is the culprit. I'm attaching some details but the main error seems to be:

ftdi_sio ttyUSB1: usb_serial_generic_write_bulk_callback - nonzero urb status: -71

Today I installed the USB wifi dongle and this was a task in itself - I had to find and compile the driver and in doing so (following several 'guides') I think I recompiled the kernal using the latest sources

176 sudo apt-get install bc git
177 sudo wget "raw.githubusercontent.com/notro/rpi-source/master/rpi-source" -O /usr/bin/rpi-source
178 sudo chmod 755 /usr/bin/rpi-source
179 rpi-source
180 sudo apt-get install bc git bison flex libssl-dev make
181 rpi-source

Attached is some information - forgive me as although I am a programmer it's been a while since I looked around a Linux system - had a mythTV some years back and it is slowly coming back to me! I believe I may have slipped up by recompiling the FTDI driver with version 7 kernal sources where I read somewhere up to v6 kernal sources with FTDI driver would be supported for the RPI. See the attached doc for output of modinfo ftdi_sio -

filename: /lib/modules/4.19.93-v7l+/kernel/drivers/usb/serial/ftdi_sio.ko

I have a StarLight XPress SXV-H9 (powered by dedicated supply), TruTech Filter wheel - powered via dedicated 12V supply, EQ6 mount and Logitech gamepad USB dongle all plugged into a 7 port Belkin powered hub (5V). Directly into the Pi I have SX Lodestar 2 guide cam (USB3 slot), BrosTrend ac650 long range wifi dongle (realtek Driver=rtl8821cu - USB3 slot) as well as the hub (USB2). I have some concerns about power and whether I may be overloading the Pi by having so many things plugged in to the USB ports. I'm doing this because my SX guidecam does not function through the hub - showing interference patterns in every image. Terry Platt at SX told me he reckons that is down to underpowered power supply to the hub but using the pi port it seems to work fine. Next on my list is a new 12v powered hub but set up like this I am getting quite good results - just some stability issues.

If anyone can help please do!

Regards
Iain

You may want to check the forum for threads about FTDI related issues first. You didn't told us what exactly was your problem. It might be that the supply you provide to the mount is not stable enough, or that the voltage shift at the FTDI level is incorrect. It might also be that your plugs are disconnecting randomly while moving.

-Eric

Hi Eric

Thanks for your reply. To be fair I described the problem in some detail - the mount intermittently disconnects while slewing and the error is in the attachment along with a lot more information. My mount cabling is fine I have been using EQMOD via a windows laptop for some years and never experienced disconnects at the mount. I did search the forum (and indeed the wider web) for more information about FTDI driver failures. I can’t find a reference to this specific error message hence my post. I’m thinking maybe it’s related to my recompiling the kernel. You’re quite right it could be power consumption from the pi which is causing the failure but that’s why I posted what I have connected - to see if anyone could confirm this error might be related to that or might be caused by something else.

Cheers
Iain

Sorry for this unwillingly rude answer, it's true that you described you problem. I suggest you use a single port for the mount and see if it's more stable. The wifi can go to the hub, but, as you observed, don't mix usb3 and usb2 on the same port tree.

-Eric

Also, you can connect electrical grounds between the rpi, the FTDI and the mount. It will help that poor non-differential protocol...

-Eric

No problem Eric! It's always hard trying to describe an issue when you're not sure what information to supply!

I will consider your suggestion of plugging the mount to a dedicated port if this issue reoccurs. It seems to be intermittent as it has not happened again and I am using the telescope this evening quite successfuly - guiding and acquiring images.

Cheers for now.
Iain