Multiplexing pots

Forum 2005-2010 (read only) Hardware Interfacing
1

I am interested in creating a custom hardware controller for a PC application I am working on, but need some feedback on Arduino. The hardware controller would simply be a 4x8 array of pots and all the hardware interface needs do is report the pot values to the PC via the USB serial interface. The hardware would be powered by the USB bus and I would use an eight channel mux to connect the pots to the A/D inputs(8 groups of 4). I guess my big concern is how much time the A/D's would need to settle on a value after switching mux channels. Does anyone have any experience multiplexing A/D channels on the Aurdino board? Is sampling 32 pots at a sampling rate greater than 150-200Hz too much to ask for using the Aurdino board? Originally I was planning on rolling my own board (using a PSOC, 4- 8channel I2C A/D's and setting up a USB HID interface) but I really would like to spend as little time as possible on the hardware design so that I can devote more time to the PC app. Thanks,

-B

2

hi

there are instructions, schematics and code in the 'playground' and on the Fluidforms site for multiplexing 64 voltage inputs. Here's the link.

D

3

When looking at a datasheet for the 74HCT4051 for example all time units are in ns (nano seconds). So the limitations is probably only in the Arduino. I think that the ADC, according to the datasheet of the Atmega, in the Arduino takes between 15 and 250us to convert depending on clock. As you can see the 150 to 200 Hz should be way within limits of what could be handled, one reading takes far less time than the 5 ms you were considering.

Nice to here about the outcome, post it somewhere!
/Markus