Linear encoder 15Mhz

I think I’ve stuffed up.
Not sure if I’ve ordered the right freq encoder.
There where different options when ordering this rls encoder.
Now I’m thinking that the Hertz is related to the drive frequency.

Will it work if I use this with out a driver.
Was hoping to plug straight in.

15MHz is probably only the maximum frequency that it can output, i.e. it limits the max speed.
Can you post a link to the datasheet?

15mhz , 1u resolution. 

My thought after servicing a resolver at work, that maybe it’s a required input frequency.

When I ordered it I thought it would be it’s highest speed.
Now I’m not sure.
They have a hole range of frequencys when going through there selection.

Quite confusing when you don’t know the smaller details

That 15Mhz is the maximum count frequency it can output at. Which is proportional to resolution and movement speed. They have a table for it on their site.

FYI you won’t be able to drive that encoder very fast. Most Microcontrollers start to fail at around 5Mhz unless they have dedicated counter hardware.


The STM32F405RG that ODrive uses does indeed have special quadrature encoder counters, which are good up to 168MHz according to the chip’s datasheet. Six of them in fact, but only two are connected due to pin count limitation. They are actually pretty standard on STM32 microcontrollers.

Resolvers are very different beasts, they are analogue devices made of just coils and iron, and they do require an excitation frequency (usually 2-16 kHz) and would need special hardware to interface with ODrive. But your RLS encoder is a normal digital quadrature encoder and should work fine.

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Fantastic news.
Finally I’ve done something right.
While I’m talking about it, the pin out has two NC and two +5v .
Is the NC for a alarm.
Does it need to be used.
Can I leave it open.

And cheers Tom for getting back to me.

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NC stands for “Not Connected” or sometimes “No Connect”, so yes, you can leave it open. :wink:

Nice work btw, I love the 3D printed cable management. :+1:

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Cheers mate.
Accounts for nothing if it doesn’t work.
At least I’ve soldiered on and not taken the easy path by giving up.
And have hope that I’ll be up and running soon.

Super cool! What magnetic linear “target” are you using? Looks like RLS sells one, but it’s about $100?

It is a rls 0.001 resolution.
The link to the data sheet is in one of the above answers.
It’s component level.
Had a mate make up the break out board.
Which he soldered for me.
It’s tiny.
Something like 6mm X 10mm x3mm thick.

Cheap compared to there other stuff.
By the time I got it and purchased the strip and transport $125australian.

Also have purchased the as5311 from ams as a back up in case this doesn’t work.

Found a supplier of 1mm pole pitch strips 10mm wide for that as well.
Yet use or try.

Aiming for 3meters a second + for bench mark.
But it will never be used at that speed