AD9850 module and Arduino mobetter!

[wb4jfi at knology.net]

By debouncing these things, I meant using software debouncing techniques, of which there are a lot (state machines, delay & test again, increment/decrement counters, to name a few).  If you only rotate the shaft ONE detent, then yes, you don’t need to worry about it.  But, most people turn the shaft through a lot of detent positions at a time, so debouncing helps.  I’ve done rotary encoders on PICs, Arduinos, and FPGAs.  If you don’t debounce somewhere, you will get very unstable results as you rotate the shaft in any real-world manner.
Terry, WB4JFI


From: Louis Mamakos 
Sent: Wednesday, March 27, 2013 7:08 PM
To: wb4jfi at knology.net 
Cc: Alex Fraser ; tacos AMRAD 
Subject: Re: AD9850 module and Arduino mobetter! 

A quadrature-based rotary encoder is of the degenerate case of an n-bit Grey code, I suppose.  You really don't need to debounce the hardware of a rotary encoder; only one switch/output should transition or bounce at a time.  If you use the awesome Computer Science power of the State Machine, the bounce will turn into jitter back and forth and eventually settle on the next incremental value.  Lots of google fodder for this, take a look at http://softsolder.com/2012/12/11/arduino-snippets-quadrature-knob/ for one arduino-based example. 

louie
wa3ymh

On Mar 27, 2013, at 6:47 PM, <wb4jfi at knology.net> wrote:


  There are multiple types of rotary encoders.  One item is how many detents per full revolution, either mentioned as number of detents for 360-degrees,  or angle per detent.

  Also, there is the encoding.  Most are grey-encoded (with A & B contacts), but within that, some go through a full cycle of encoding per detent, while others stop halfway through an encoding cycle (hard to explain, but easy to see in action).

  I’ve been bitten by both of these a few times.  My favorite is the Grayhill 61C11-01-08-02, but that’s an optical encoder, and pretty expensive.  You can get inexpensive ones from many sources, including Electronic Goldmine and other surplus parts places.  Just plan on testing whatever you get, and maybe have to adjust the software to adapt.  The Adafruit one mentioned elsewhere also looks good at first blush.

  The optical ones are better because they have far fewer problems with keybounce.  Cheaper rotary encoders can have a LOT, LOT, LOT of bouncing – to the point of being unusable.  Optical encoders REQUIRE that you observe polarity!!  I’ve burned out one nice but hard-to-find encoder by accidentally miscounting the pins.  It got hot, fried, and is now worthless.

  Also, make sure that if you need the push-button option (pushing of the shaft), that whatever you buy has that extra switch as well.
  Terry, WB4JFI


  From: Alex Fraser 
  Sent: Wednesday, March 27, 2013 1:49 PM
  To: tacos AMRAD 
  Subject: AD9850 module and Arduino mobetter! 

  I added "VFO" to the original Google search string "Arduino AD9850"  and found this gem.
  http://www.ad7c.com/2013/02/7mhz-vfo-with-arduino-and-ad9850/
  I don't know the details on the Rotary Encoder.  I've written off to AD7C (Richard) for that info and maybe a part number to make ordering easier.  If any one recognizes the device please chime in.   I also asked if he would mind us linking to his site on the AMRAD site.

      He also includes a .sch file which I believe is a way of showing a schematic or making a board. Any recommendation on software for that?

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