Hi,
I'm generally looking for an advise with this topic.
I'll give a big picture here but my question is about ADC usage.
I'm building an app which should be able to replace analog car gauges.
All I know about gauges is that they will have some voltage on them 0-12 (* technically 0-14.5 or even more, but for simplicity let's say 0-12) because on the other end of the wire there is a sensor that will drop some voltage from 12* to something because sensor resistance changes cause of temperature, oil pressure, etc...
I've already got almost everything ready except getting actual measurements from ADC.
Before voltage comes to ADC's input it comes through voltage divider 1:7 safe on that side. And I'm not after insane accuracy as gauges that I want to replace even less accurate.
My plan was (since ADS got 4 ports) use channel 4 for measuring current "full" voltage (or base voltage) in the car (AKA ~12v *) measure on 3 other channels readings from sensors.
Since car voltage isn't stable thing plan was to make proportions between measured voltage on channel 4 (base voltage) and other channels and then using formulas replicating gauge behavior calculate my values, display them. Actually readings of channel 4 going to be feeding voltage gauge. And so all channels would be in good use.
There are few factors that making me write this post:
- I also care about performance of the whole process (CPU wise) and If I could avoid some calculations - that would be ideal.
- Since I can not read all 4 channels at once - I will be reading them sequentially and base voltage when reading pin 4 might be different when reading other pins - that might introduce unwanted errors.
- Somehow (can't say where I picked it from) I think that these ADS can directly measure voltage difference between channels. Or am I wrong?
If ADS1011/1115 for real can give me the difference between channels should I rather do that? And that would eliminate a need of some calculations?
If yes ADC can do that and yes I should do that - may be some little example?
And if that is the way to go - will I still be able to measure voltage on channel 4 - to feed my electrical voltage gauge?
And finally.
would you advise to code some kind of software filter (I think they called "low pass filter" not sure though) to avoid random spikes in displayed results or would you say that it is not necessary?
How frequent realistically I can make each following reading from those ADS1011/1115?
Thank you very much!
4 posts - 3 participants
