New Project. G11 and OnStep. Which Board, CPU.


Pete
 

I recently purchased a Losmandy G11 that has a Gemini 1 system attached.  The servo motors are noisy and the clockwork toy car gearboxes are truly horrible.  This will be my fourth OnStep project abut I really need advice as to what to build.  I am 3D printing the motor plates from PETG and if project is as good as I hope, I shall make some more from aluminum plate.  Obviously I'll use Nema 17 400 step (0.,9 degree step) motors but there I stop.

I would also like to replace my home built focuser and to use the one Howard has in the MaxPCB2.  I used a Nema 14 motor and the mechanics work well but I'd like to get the controller off my scope and into OnStep. 

Lastly I would really like to use wired Ethernet as I always look at that micro USB with circumspection.  It is weak and flimsy and carries all my data.  One flailed hand in the dark and I have a solder repair job or a new Teensy to contend with.

So. what do I build? How do I get where I need to be please?

Thanks for your help and advice.
Pete


George Cushing
 

For a G11 I think one of the Max PCBs is the way to go. They all can use the $13 aluminum case, which fits the Losmandy brackets. The MaxSTM3 (SMT) uses the more robust USB jack. Another option is to integrate an Ethernet Module For Arduino SPI in place of the Wifi module. all the Max boards have quite a bit of real estate to play with.


Pete
 

Thanks George,  My thinking is running along the same track as yours.  I should have the motor brackets 3D printed this week and I can try them out with a spare Mk. 1 MiniPCB that I have here (JLCPCB - minimum order of 5...).  I have a spare Smart Hand Controller too.  Making it work is not the problem.  Getting the configuration I want that has the options I want is the puzzle,

II am in the process of building my own roll-off roof observatory and I hope to complete it this fall.  We shall see,

Thanks for your help.
Pete


Khalid Baheyeldin
 

On Sun, Jul 18, 2021 at 09:39 PM, Pete wrote:
Lastly I would really like to use wired Ethernet as I always look at that micro USB with circumspection.  It is weak and flimsy and carries all my data.  One flailed hand in the dark and I have a solder repair job or a new Teensy to contend with.
If this is the only reason for Ethernet, then there are boards that have a USB-B connection, which is much more sturdy than the microUSB. The FYSETC S6 is one of them.

If you want Ethernet for other reasons (speed, less variability, ...) then please note that you need two modules just for that: an Ethernet module, and a microcontroller (usually a Teensy). The reason for this is that for Ethernet we don't have an integrated module like the Wemos which is an MCU + WiFi.
The Wiki has more details.

For the focuser, almost all boards support at least one focuser. Some have more than one.


Pete
 

Your usual good points Khalid.  Thanks.  I actually have a USB to Ethernet adapter here.  I may try it.  Speed, I do not believe is an issue it is more the mechanical weakness and the ease of finding/making cables that re the correct length. Then there is the shot run length of USB within the observatory.  Ethernet is without doubt my preferred choice but I'm sure I can make it work with USB if I have to.

Pete


Pete
 

The case and the PCBs are on order.  I have stepper motors and drivers kicking around even though they are only 8825s, they will get me going.

Question: Should I go with a Teensy 3.5 or 3.6?  The 3.6 is faster 180 Mhz vs 120 for the 3.5 and the 3.6 has double the memory.  However the 3.5 has all pins tolerant of 5V, which may be useful.  My Teeny 3.2 in my old mniUSB boards work just fine.  I plan on using TMC5160s as a final solution.  Does this affect the CPU choice?

Thanks.


Howard Dutton
 

On Tue, Jul 20, 2021 at 07:25 PM, Pete wrote:
Question: Should I go with a Teensy 3.5 or 3.6?  The 3.6 is faster 180 Mhz vs 120 for the 3.5 and the 3.6 has double the memory.  However the 3.5 has all pins tolerant of 5V, which may be useful.
The 5V tolerant pins are handy.  I don't anticipate you needing the speed of the T3.6

My Teeny 3.2 in my old mniUSB boards work just fine.  I plan on using TMC5160s as a final solution. 

Does this affect the CPU choice?
No.


Howard Dutton
 

On Wed, Jul 21, 2021 at 03:20 AM, Howard Dutton wrote:
On Tue, Jul 20, 2021 at 07:25 PM, Pete wrote:
Question: Should I go with a Teensy 3.5 or 3.6?  The 3.6 is faster 180 Mhz vs 120 for the 3.5 and the 3.6 has double the memory.  However the 3.5 has all pins tolerant of 5V, which may be useful.
The 5V tolerant pins are handy.  I don't anticipate you needing the speed of the T3.6
Just be sure the board you ordered is a MaxPCB2!  You really didn't say.


Pete
 

Thanks Howard.  5V compatibility is always handy I'll order a Teensy 3.5.  Done.

Here's the board I ordered from JLCPCB.  I am sorry I did not specify the board.  I just figured everyone was now using the MaxPCB2, as I now shall.