I'm reading the datasheets for that right now, and it looks good. Trouble is, I'm very much in the prototyping stage of my project, and as a personal interest I'm having to support the cost all myself. I'm starting to come to the conclusion though that for what I want, $150 or so might be my only option? Sorry, I probably should have mentioned that cost is a factor.Newark carries a Simpson rotary optical encoder...
Hey, that's getting closer to what I need! But it's so small! What does it mean by 10-bit analog output?dknguyen said:How about this one?
Hank Fletcher said:I think I'm just new to what the benefits are to having the 10-bit PWM signal, particularly since the analog signal according to the site has a twice as good sample frequency? The plan is to put the encoder signal into the 10-bit A/D of a PIC mcu, if that helps explain where I'm coming from.
Hank Fletcher said:The big pulley in the photo rotates just less than 360 degrees to accommodate movement over the entire length of the slide, that is, the circumference of the large pulley is just slightly greater than the length of the slide. For that reason, the pulley will never need to rotate more than once in either direction. I should say that the photos represent an early prototype - eventually the pulley/line will be a little different so that the line (actually two lines) are permanently attached to the pulley, which at that time have two grooves for separate lines in either direction. Sorry, I know that might be hard to visualize, but the short of it is the new set-up will eliminate drift due to the line sliding on the large pulley when it's in motion.
The PWM signal from the encoder you mentioned interests me, but I still don't understand it. What's the difference between reading the voltage of a PWM signal and an analog signal, and how do I go about reading it in a way that avoids the noise you mentioned? I think the PIC mcus have PWM capture capabilities, but I'm still trying to put it all together - any thoughts?
That's what I've been taking issue with! If the PIC just reads the ratio, then even if it's a digital PWM signal, it's still subject to interference, isn't it? Or does the PWM capture module on the PIC have (what I would call from my music recording knowledge) a built-in noise gate so that that's a non-issue? What you're telling me is that the PWM capture on a PIC will only pick up the individual bits, and not do what I'm anticipating, i.e. simply act as an A/D that averages out the highs, the lows, and all the interference? See what I mean? You could put a PWM signal to an A/D, and the A/D would just give you an average of everything coming in (even the noise). But what you're telling me, and what I'm really wanting to hear, is that you can put a PWM signal into a PIC's PWM and get exactly and only the PWM bits read. Right?either that or it will read out the ratio between the two (the duty cycle)...
So how does that work in a PIC? If it says it has 10-bit capture at a 1KHz sample rate, will it actually be taking more measurements than 10 bits times 1000 per second, and then averaging out however many samples it's actually taken into a 10-bit value? I mean, in practice, despite the errors from clock jitter, does the PWM approach still beat out the analog approach, presuming in both cases your best means of capturing either is, for instance, a 16F88?Errors in PWM come from the jitter in the clock used to generate/measure it. Averaging is also something that is inherently done with PWM due to the multiple measurements that are taken for a reading,
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