6HC + external servo drives at high step rate

Andrey

Hi all!

Is it possible to hookup 2x external servo drives to 6HC without using 1XD? Can I use I/O pins while sacrificing some minor functions? High step rate needed.

jay_s_uk

@Andrey unfortunately not.
your options are

1XD boards
A 6XD in expansion board mode
An STM32H7 board in expansion board mode

dc42

@Andrey that's not currently supported. In principle we could support one or two external drivers as an option, but it would have some limitations:

you would need to use 2 output pins per external driver if you don't need the Enable signal, or 3 if you do
if using the ioX_out pins then you would need to boost the drive voltage from 3.3V to 5V

Andrey

Thank you for your reply.

@jay_s_uk

I have couple of 1XD for Z-axis motors and it works just fine but unfortunately it can not handle 220-250 kHz step rate needed for XY-axes (maybe it could be a good idea to develop hi-speed version of 1XD).

6XD itself is more than enough for my task and I have two boards in work right now. 6HC is one of my first Duet boards and it works great for several years now I just want to prolong it's life in new project.

STM32H7? I can get any STM32H7 development board and connect it via CAN-FD?

@dc42

Yes 4 output pins looks like fair price for external drives. Enable signal does not that important and XY-axes drives definitely can share it (so OK, it is 5 pins needed).

Hi-Speed logic level shifter adds something around $6-10 and it is OK I think.

jay_s_uk

@Andrey the STM32H7 boards that are supported by the STM32 port are listed here https://teamgloomy.github.io/supported_boards.html#stm32h7-boards-with-native-support although I would discount the Fysetc Spider King.