Multiple Inputs with SSC32

Lynxmotion Electronics & Software
1

Hi guys!

Long time, no see! I just ordered my second hexapod and preparing for it.

I want to connect several sensors with the SSC and I am wondering how to connect more than the 4 available inputs. Main problem: I am a programmer, but an electronics noob, though I know at least a little soldering

My current idea - not to involve additional electronics - would be to power the sensors over the SSC outputs, wire them to one input, and power/reading them alternatingly. Guess this would work for pressure sensors, but with accelerometers I am not sure if those respond quickly enough to power them 20 times per second or so. Or if they get damaged by this.

I read and heard about multiplexing and I guess I know from the pinciple what it is, but nothing more. I believe its the more professional way, but I don’t know how to use them. Can you recommend any plug’n’play solutions, or do you have any tutorials, how to implement one? And which one to buy?

Or are there any other, easier solutions? Any hints would be greatly appreciated :slight_smile:

Thanks in advance

2

The below board might be of interest.

sparkfun.com/products/9056

3

Hey Zoomkat,

Thanks for that. Does it come with a thorough documentation? Are there any examples out there, to figure out, how to wire the board?

4

The board is based on the CD74HC4067 chip. Down the page of the provided link are links to the schematic, chip data sheet, and such. Fairly simple operation where four digital output pins on the ssc-32 would be used to control the chip to switch between sixteen different inputs.

5

So I guess it works a little bit like a switch?

According to this image: bildr.org/blog/wp-content/upload … thPots.png
I get it like the following:
The blue wiring is like connecting the board to 4 SSC (digital) outputs, to trigger the used input with the bitmasks? So I enable the needed input, then read the analogue value.
The inputs C0-C15 are analogue inputs, and on this image
bildr.org/blog/wp-content/upload … thPots.png
the wiring is explained, how to connect sensors, that are resistor? right?

Please correct me if and where I am wrong :slight_smile:

6

Yes

Yes

The attached devices are pots (variable resistors) used as voltage dividers to input differing voltages.

7

OK, I see, I see :slight_smile: Thanks for your answers!

Actually heard about voltage dividers, so I think I will get it.

Last question would be: What is your experience about the frequency, the sensors outputs can be read? If I have like 10 sensors connected, is a frequency of 25 times per second for each sensor realistic? What should I exspect?

Regards

8

I don’t think that is realistic with the ssc-32 (new reading every 4ms). I think the ssc-32 may require up to 30ms per request. You can look at the ssc-32 documentation for more info.