I am working on a project, where I need as many datapoints as possible. I currently am using 36 sensors but I would like to eventually double that number.
I can set up the sensors to give me either an analog or digital reading. For analog readings I use regular voltage dividers, for digital readings I place a capacitor before my sensor - I then send out a signal and measure how long it takes for the capacitor to discharge. So basically both methods work fine, however the digital one is slightly slower. (A binary reading is not usefull, thats why I measure discharge time.)
My application is time sensitive, thats why I would prefer to use analog inputs. However, if I use multiplexers, I am afraid that this will slow down the system, once the ratio of sensors to "actual" analog inputs becomes higher.
I am using the arduino purely as an interface. The arduino simply reads the sensors and passes them on to the computer.
- I feel like an arduino might not be the right tool here - can you think of anything more appropreate?
- Does anyone have any experience on whether this shield: http://www.sparkfun.com/products/9832
would slow down the data readings? and if so, how strongly?
(with slowing down my reasoning is this: if I would read 48 signals [or more, with additional multiplexers] , I will read them on at a time. I need to wait until I have logged 47 signals, before I can measure signal 1 a second time. If this effect is too strong, it may mess up my application.)
- Are there an AD conversion shields floating around? I have never seen any, and google pointed me to some code examples for IC's which looked like setting them up would be a lot more work than I am able to put into it...
- Could daisy chaining (well, vie hardware serial) a couple of arduino Megas do the trick?
Any generall thoughts on how to tackle this?