AX58100

Hello Hakan and thank you for all your work.
If I want to create a small PCB in order to add encoders, compatible with LinuxCNC, which version of your project would you advise in order to modify it?

Thanks

I would start looking at
- encoders. With the current stm32f407 the quadrature counters are tied to certain pins, and max 4 such hardware counters. Code is in E3000, would copy that.
- EtherCAT chip, would base it on LAN9252 (which most of the cards use) due to Ax58100 limit of 2x16 pdos. Don't know of a limit for LAN9252, it's not less than 2x16. 
- Opto-couplers, would revisit.

If you are thinking of stepper generator with encoder inputs, say for four of them, would base it on E3000 for the user code and extend to four encoders, code is already there. soes library from E7000. Hardware will be based on E3000 around stm32, around E7000 for EtherCAT.

One can think of one card supporting 1 drive. Or 2 stepper drives. And use multiple cards

In linuxcnc 2.10 there is 64-bit integers, so no risk for encoders overflowing. 32-bit isn't quite enough at least for spindles.

Is it just an idea, or are you going to do it?
.

Hello,
Thank you for your reply
Ideally, I would like to integrate the project from PedPex which is a COS SIN converter (with IC-NV chip) for heidenhain glass scale directly as an ethercat module. It would receive COS SIN signal, convert it to quadrature, read by the STM32 then sent to Ethercat.
But this is a little bit out of my league knowledge wise, even if you did most of the job regarding ethercat and Pedpex most of the job regarding COS SIN conversion

I don't know much about cos sin. The whole processor is available for you to do all sorts of processing.
The ethercat part is the easy one I would say.
Every cycle you calculate a new encoder value, set a pdo variable and the soes library does the rest.

Edit. But I checked quickly. So you need to take in two analogue signals and calculate the phase angle.
Absolutely doable, could be a nice application.
Start a project thread and I'll give you a hand with the ethercat stuff.

Edit 2. The ADCs on STM32F4 are only 12-bit, you may need 16-bit ADC for this. Another processor? 
External 16-bit ADC unit?

Edit 3. IC-NV instead of ADCs of course.

IC-NV are here for the conversion, not easy to setup but Pedpex, a member from the forum did the stuff.
My goal is to merge his project to yours basically.

I will prepare all the work environment and when the schematic will be done or almost I will open a thread. Maybe i should start with a prototype PCB from you as I already get a pcb from pedpex and when everything is running, I do the merge

I found Pedpex's work, awesome.
Maybe that is what you have in mind, but I would put his circuitry on the same board as ethercat
to have it neatly packaged.
One thought I got is if one can skip the quadrature part in some way. Are there sin cos chips
that can deliver a value over spi or i2c for example?
The built-in quadrature encoder in stm32f4 can read with at least 3 MHz so maybe not a big problem.
I have code to extend numbers over the 16-bit and 32-bit boundary.
Code for encoder counting is in E3000 project. 
Best to base HW on E7000 project, clear out pins and I2C and add encoder inputs.