Support for BISS-C Encoders on 1HCL via IC-Haus IC-MB4 Chip

[lee7670]

Hello,
It would be extremely useful to support using an absolute linear encoder to close the position loop on BISS-C Absolute Linear encoders as the linear element in a dual loop configuration.

To that end, there is a relatively (~$10USD) affordable IC that is SPI accessible that can handle 2 BISS-C/SSI encoders.
https://www.ichaus.de/product/ic-mb4/
US Sample Shop
https://us-shop.ichaus.com/ProductDetails.asp?ProductCode=iC-MB4-QFN28-5x5-SAMPLE
German Sample Shop
https://de-shop.ichaus.com/ic-mb4-qfn28-5x5.html

In this case, instead of using the duet magnetic encoder on the motor and a quadrature encoder on the load,
you could use either a quadrature encoder on the motor and a BISS-C Absolute linear encoder on the load.
Alternatively, the IC-MB4 supports 2 BISS-C encoders when used with external RS-422 transceivers so you could just use a second absolute Biss-C encoder on the motor itself, so you don't have to phase the motor upon power on.

Examples of BISS-C encoders that are applicable to this use case
Renishaw Resolute
https://www.renishaw.com/en/resolute-encoder-series--37823
RLS LA11
https://www.rls.si/eng/la11-linear-absolute-encoder?

[ironhydroxide]

This would also help me,
With BiSS-C I would be able to select an appropriate encoder for my desired setup (17+ bit resolution required)

There's a post I found where someone was supposedly able to "read" a BiSS-C encoder with SPI in the "SimpleFOCproject" community forum. (can't post links yet, but search for SPI BiSS-C SimpleFoc and it'll likely come up. )

[Notepad]

+1 here, Those encoders are VERY nice. and support would be sweet. Not sure what complications there might be however if there are firmware limitations

[T3P3Tony]

I have raised a feature request for the firmware part of this here:

https://github.com/Duet3D/RepRapFirmware/issues/1068

T3P3 created this issue in Duet3D/RepRapFirmware

open Support BISS-C encoders #1068