Mayhew Labs Rotary Encoder LED Ring Review

[jmole]

Hey all,

I put up a review of the Mayhew Labs Rotary Encoder here:

Check it out if you're thinking about using a rotary encoder surrounded by LEDs in your next project. There are certainly some caveats that I found with their product that you should be aware of.

[Rufus]

Hey all,

I put up a review of the Mayhew Labs Rotary Encoder here:

I spent half the video trying to turn the scope channel 4 vertical position knob.

The board is an LED ring with a footprint for a rotary encoder tracked out to a connector. Using an encoder on the board is the same as using an encoder without the board which is what I would expect. Some footprints to optionally add pull ups and filtering would have been nice.

[AndreasF]

Nice video! I agree that given the target users of the board, it would have probably been better if they had put on the pull-up resistors and the filter circuit. It's also not surprising that a microcontroller will not reach the kind of speeds that a dedicated hardware decoder can reach.

However, at the fast rotations speeds you were doing, you're probably exceeding the physical limits of the encoder itself already. On the datasheet you show, you can see that it gives the maximum operational RPM as 60, so no more than 1 full rotation every second. That's a fairly typical figure for this type of encoder, and probably also the reason why potentiometers are still used more often as input devices when you need to be able to change parameters quickly (optical encoders being the other option).

[jmole]

Nice video! I agree that given the target users of the board, it would have probably been better if they had put on the pull-up resistors and the filter circuit. It's also not surprising that a microcontroller will not reach the kind of speeds that a dedicated hardware decoder can reach.

Thanks! Yes, the freesoc works great with it, but I'm still irked about the lack of pullup resistors or a filter. I really wanted to run 4 of these into 2 daisy-chained parallel load shift registers, like the HC165, and use some verilog code in the freesoc to quickly shift the data in to the quadrature decoder components, so I could use 4 rotary encoders, with LED rings, and only need 6 I/O pins. Now that I know I need a filter, I'm probably just going to roll my own board for these.

What was a little surprising to me was that the actual period of the quadrature data was pretty long, on the order of a millisecond, even for fast turns. Makes me wonder how many you could chain together with parallel load shift registers and still have decent update rates.

However, at the fast rotations speeds you were doing, you're probably exceeding the physical limits of the encoder itself already. On the datasheet you show, you can see that it gives the maximum operational RPM as 60, so no more than 1 full rotation every second. That's a fairly typical figure for this type of encoder, and probably also the reason why potentiometers are still used more often as input devices when you need to be able to change parameters quickly (optical encoders being the other option).

I didn't think about this actually, and it would've been a good addition to the video. I think I will do a followup video on this in the next month or two where I compare some optical encoders to a mechanical encoder like I used in the video. Just need to find some optical encoders that are suitable for the kind of knob-twiddling I want to do.