1Vpp Encoder to Mesa 7i33

Yep Andy, I already was considering this way as I have AT91SAM7S256 dev board. It can also incorporates Hiperface interface as absolute positioning. To be honest its a bit tricky and time consuming way compared to "offshelf" IC-VN chip.

There is just one open question for me regarding BLDC hal component and 8i20 driver card linked to need of absolute position.

8i20 should know rotor position by hall effect current sensing? If yes, how I get this information to BLDC to be synchronized where the rotor actualy is? Maybe I am lost in understanding of the principle, I am sorry for that.

pavel7890 wrote: 8i20 should know rotor position by hall effect current sensing? If yes, how I get this information to BLDC to be synchronized where the rotor actualy is? Maybe I am lost in understanding of the principle, I am sorry for that.

I think you may be confusing two uses if "Hall effect"
A typical brushless motor has Hall sensors in the motor to feed-back the absolute rotor position.
The bldc component watches these signals changing and uses the first transition that it sees as an absolute reference, and then switches to using the encoder value to give a more fine-grained position.
If your motors have a Hiperface encoder it is possible that they don't have Hall sensors, which may make getting an absolute position reference rather more difficult (Hiperface might be the _only_ way if the encoders have no index pulse.)

The blcd can do "bump" alignment, but that isn't very reliable under load.

The Hiperface documentation describes: motor shaft aligment with absolute position has to be stored just by manufacturer and never changed by user. I cant justify this by now, but if this is true, I can use absolute position from encoder to sync quadrature counter before BLDC.init and there should not be any bumb.

I just proceed with Hiperface encoder RS485 interface with positive results. Its in principal easy to understand and implement into HAL.

I am just curious about one interesting feature of the encoder. I tested absolute positioning by shaft turning after power off. I would expect that after power on, the encoder can provide shaft position within 360 deg, but he was even able to provide number of revolutions too!!

How this can be done? There might be a battery or some kind of different mechanism I do not know about.

Anyhow, this feature gives me perfect feedback not only for commutation but for machine positioning after power on.

I have Heidenhain linear scales that output 11uApp and I found Heidenhain EXE 602 interpolation boxes on ebay for 60.00 each. Not sure what you need for 1Vpp output but it may be available fairly cheaply used compared to the Heidenhain price. Sorry, thats the only information I have.
Paul

pavel7890 wrote: I just proceed with Hiperface encoder RS485 interface with positive results. Its in principal easy to understand and implement into HAL..

Can you give more details? Is this something that could be a released HAL component?