First I’d like to say I’m fairly new to Arduino but I’ve found this forum to be incredibly helpful. I’m reaching out to anyone who can point me in the right direction for a small project I’m working on.
My objective is to measure the resistance between multiple inputs. I don’t even need the actual number, just whether the connection is present. I’ve successfully coded to read resistance on an analog port but my problem lies as to how I can to select and measure multiple connections.
Below is my hand drawn schematic. Please forgive the roughness of my sketch.
Basically, I need to be able to select which inputs to use (like a switch), then measure the resistance and report it. For example, select/open a connection between 2 &7, measure the resistance in between, and report it to Arduino. Can someone tell me what type of component I need to handle this many connections? Shift register, multiplexer, mux shield? I assume the device needs to have analog pins to obtain the resistance readings.
That part is 4 analog switches, not an analog mutiplexer.
It can be wired up as a mux.
Can any 2 pins be connected together? Or is there some pattern to the pairs?
What you can do is wire two switches back to back, drive an output into 1 common, connect the other common to an analog input. If the analog input also has a resistor to Ground, then a voltage divider is formed and you calculate the resistance between the pins.
The analog switches can be a part like DG406, appropriately controlled by Arduino, need to take its internal series resistance into account, unless you are just looking for a High/Low kind of result.
CrossRoads:
Can any 2 pins be connected together? Or is there some pattern to the pairs?
Yes but the left set of inputs can only be connected to the right set of inputs, one at a time (using the mux i assume). None of the pins are connected together on their same side... Hopefully this makes sense. Will this still work with our proposed sketch? Thank you!
You linked a post about using a voltage divider instead of just answering that you are going to use a voltage divider. Why do we need to see a post about a voltage divider ? (we do know what it is you know). We don't need a link. Can't you just say that's what you are going to use ? The reason I mention that is it leads me to believe you don't know voltage divider basic calculations or analogRead to voltage conversion calculations and that we are going to wind up discussing that . Is that the case ?
raschemmel:
SORRY ! You're right Crossroads. My typo (if it's any consolation the link I posted IS for an analog SWITCH,
NOT a MUX) (ha, ha)
You linked a post about using a voltage divider instead of just answering that you are going to use a voltage divider. Why do we need to see a post about a voltage divider ? (we do know what it is you know). We don't need a link. Can't you just say that's what you are going to use ? The reason I mention that is it leads me to believe you don't know voltage divider basic calculations or analogRead to voltage conversion calculations and that we are going to wind up discussing that . Is that the case ?
Hey look, I'm a NOOB, I'll be the first to admit it. I'm simply looking for guidance to point me in the right direction....I'm not asking you to explain the logic. I can learn that on my own time without wasting yours. Sorry if I insulted you by posting a link.
Everyone has to start somewhere. If this isn't the right forum for it let me know, and I'll go elsewhere.
I'm not insulted. You're asking for help and I'm asking you what help you need. If you need to know how
to calculate voltage divider or convert analog values, we need to know. You don't have to overreact. I am
simply stating that the fact that you posted the link suggests you need that information. If you don't need
to know how to do that simply say so and we can move on. We try to keep emotions out of the equation and just deal with the facts. Your call.
Yes I'll need help calculating both if you don't mind. I can partially make sense of the code the user in the link but it would help if you explained it.
