Hi everyone,
Sorry cause what follows is long, this little nightmares usually are...
![:lol:]( ":lol:")
I'm using a Raspberry Pi 4 to control a mount (Skywatcher HEQ5 pro) and two cameras (ASI 1600mm pro and ASI 120MM) over VNC (using Astroberry). The cameras are connected directly to the USB ports of the Raspberry and until recently I was using a USB to serial TTL converter to connect to the mount via the handcontroller (USB-TTL adapter -> DB9-RJ11 cable -> hand-controller -> mount). I had to try a couple of USB to serial adapters until I found one that worked (based on FTDI 232RL,
this one
).
Unfortunately, connected as such I experienced two problems:
1- Guiding seemed erratic, particularly in DEC, sometimes jumping several arcseconds when only a small correction was due. After ironing out as much backlash as possible and seeing no improvement I decided to try guiding through the ST4 port instead of EQMod... It worked perfect! (and does it every time, no jumps, totally predictable, 0.55 asec RMS in RA, 0.45 RMS in DEC over 20 minutes).
2- Every now and then, pointing anywhere at the sky, INDI would complain briefly that the scope is out of limits (!). Other times it will disconnect out of the blue. This made guiding impossible even if using the ST4 port because upon reconnecting the driver would not activate tracking by itself.
I took this as a clear sign that I was better removing the hand-controller of the equation. I took the DB9 plug of my old cable and used one half of a CAT5 cable with its RJ45 plug to make a DB9 to RJ45 cable 1 meter long (following the pin-out shown on several websites). First try into the motor controller port: no go, nothing. Raspberry sees the adapter, adds device (ttyUSB0, as before), EQMod driver detects it, but no communication. I tried reversing TX and RX leads. Nothing. I thought maybe the adapter defaults to 3.3v levels and inexplicable that is enough for the hand-controller but not for the motor controller.
Bought me a FTDI 232RL breakout board (the kind that has a jumper to switch between 3.3v or 5v levels,
like this one
). This time, before soldering anything I used a breadboard to provide temporary connections from the FTDI to another half of a CAT5 cable and try the setup. It worked! But: the motions lagged the commands significantly, most goto's would take several iterations to get to the target and the driver kept randomly complaining that the scope was out of limits. I thought (hoped) this was due to the bad quality of the connections provided by the breadboard as it hanged from the mount. I soldered the new FTDI adapter and CAT5 cable to make a definitive EQdir interface. In addition to not requiring the DB9 connection in between, given that the FTDI breakout is connected by a USB cable to the Raspberry, I cut the CAT5 cable to less than 10 cm so most of the new cable is a USB cord.
Unfortunately, this didn't work better. Connection was unstable, goto's were unpredictable, warnings all over the place. I left the mount unattended for 5 minutes and had to run back to it in horror when I heard the sound of the gears skipping as the scope was hitting the tripod
![:pinch:]( ":pinch:")
.
I rebuilt the DB9-RJ11 cable to try and use it as before. Also used it to update the hand-controller firmware from 3.39.05 to 3.39.10 (update that initially failed of course...).
I have attached two logs to this message, both from earlier today. The first is using the PC Direct mode, the second is using the FTDI 232RL to RJ45 cable. Now, I don't know if this is a coincidence or not, but today I was unable to observe any warnings using the PC Direct mode (this is after the firmware update). The log of the FTDI to RJ45 cable on the other hand is plagued by "read errors".
I'm puzzled...
- Would my problems be fixed if I go and buy a ready-made EQdir cable?
- Why does the USB to serial adapter work when used through the hand-controller and not when used to communicate directly with the motor controller?
- Is the motor controller of my mount the source of the communication problems? (but then, why would it work when driven by the hand-controller?)
- Faulty FTDI breakout board?
What do you think?
All the best,
Ricardo
.
