Quote from: PeterH on Oct 11, 2012, 09:12 pmIf your requirements are so close to the resolution of the ADC that a variation of one or two is important to you, you probably need to use a more precise ADC.Under battery power the ADC is pretty well behaved (certainly noise below 1 lsb) - I suspect this is power supply noise - is the PSU a switching one? Extra decoupling can help.
If your requirements are so close to the resolution of the ADC that a variation of one or two is important to you, you probably need to use a more precise ADC.
The first thing I would try as a simple experiment would be to remove the external Aref voltage you are applying to the Aref pin and use the instead default internal Avcc reference and see if your wobble improves, gets worst, or remains the same. Lefty
4. Induction in that 4 meter cable (from near by mains cables) is the cable shielded?Mark
Quote from: retrolefty on Oct 15, 2012, 10:54 pmThe first thing I would try as a simple experiment would be to remove the external Aref voltage you are applying to the Aref pin and use the instead default internal Avcc reference and see if your wobble improves, gets worst, or remains the same. LeftyLefty, Aref was only tried after suffering with wobble and made very little perceivable difference compared with the Unos' default 5V. I should just check: When you say 'internal', do you mean something other than using the 'DEFAULT' Const when setting the reference in 'analogReference()'...this is how it was being used prior to using the Aref pin (although it was used by default, i.e. no specific call to 'analogReference()')...Thanks Lefty
Lefty just in case I've negated a negative (!?), the first implementation displayed similar wobble without the function 'analogReference()' being called.It's interesting what you say about alternative chips and I wonder whether you have any models in mind. I admit that I'm trying to do this on half a shoe string, but a few quid of prudent expenditure is surely horses for courses.Thanks for your view...
TI ADS1115 16 bit
QuoteTI ADS1115 16 bit Let me be the first to say that unless you are a very good engineer, using a 16-bit adc can be quite a challenge. And unless you are some analog god, using a 24-bit adc can be downright impossible.Rather than increasing the bits, you should think if you need that much resolution and if that high of a resolution makes sense for your application (for example, is it even that accurate?).
The technique used (so far) places the light half on one colour and half on the other colour, which provides the average greyscale as output. To move from fully on one colour to fully on the other the image needs to travel around 1.5mm which provides less and less resolution the lower the relative greyscale values get.
Lefty I'm amazed at how small the chip is, no wonder it's offered with a breakout board. Do you happen to know of one that might be attachable to a breadboard so that I can experiment cheaply.
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