JWoodrell 285 Posted April 16, 2013 Share Posted April 16, 2013 guys. a side thing I am working on starting I need to measure the rotation of a dial. the motion is continuous (can free spin one direction forever) and can just be relative incremental, doesn't have to be accurate over many rotations, it just has to track changes in dial position. the original circuit I am replacing was limited to 270 degrees motion only (had stops to prevent continuous rotation) and used a potentiometer. but I want to add the free spinning capability to the new version My first thought was to use an A/B rotary encoder like they use on mouse scroll wheels, but those only give me about 24-48 steps per rotation. the original circuit had functionally around 220 steps per rotation. a rotary encoder with that many steps is too expensive.(around 70 bucks) my current plan is to gut optical mice for their sensor + lense i can get them for around 2-3 bucks. the first mouse i gutted had an AVAGO ADNS-2051 sensor which is nice because it has a serial interface, but also has hard quadrature X and Y outputs to track. I am going to have to wait and see which sensor these cheap mice have in them but it seems most optical mice use some avago sensor or another. I can source just the sensor chips for around 2 bucks on aliexpress, but I have yet to find a place to be able to get the lenses, so I am stuck gutting mice because they already have the sensor + lens + ancillary circuits like appropriate crystal and whatnot. basucally use the optical sensor and have it watch a flat disk attached to the dial, so it works like a mouse moving on a surface, and just reports the motion back and forth on that "surface" the good thing is that optical mice have anywhere from 400 to 2000 counts per inch, and even with a 3/4" disk that is 900 to 4500 steps per revolution. the pin layout for the 2051 was interesting to me, it is 100mil standard spacing on the pins, but the left and right sides are offset from each other by 50mils so its a staggered 16 pin arrangement, although this looks normal for avago chips. the downside is you can't use standard prototyping board at 100 mil spacing, unless you use 2 pieces for the offset does this seem like a good route to go, or am I missing something simpler in how to accomplish this? thanks guys Quote Link to post Share on other sites
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