CIRCUITRY: 8-Bit Clock?

Question

I have 4 continuous analog data streams into a circuit board, but I want to alternate which stream of data I am utilizing. The target board only has 1 available digital input and 3 available analog inputs, so my plan is as follows:

Use a DPDT and two SPDT switches to determine which signal is being used. The 8-bit logic will perform as follows:

000 - Ground

001 - Signal 1

010 - Ground

011 - Signal 2

100 - Ground

101 - Signal 3

110 - Ground

111 - Signal 4

As you can see, the signals are all separated by a buffer 0V signal for later sorting.

My plan is to have the signal being routed goto the DIGITAL signal, but have the 3 output signals from the clock (H/L for each bit output) goto the analog inputs on the robostix. By sending the clock timing as well as the signal, the data should then be able to be later sorted computationally.

My question is as follows:

1) Which type of SOIC can continuously count from 0 to 7, in binary, and has a output referencing each of its 3 bit slots?

Answer 1

I'm not sure I understand, you want to multiplex the Analog signal into a Digital input?

"My plan is to have the signal being routed goto the DIGITAL signal, but have the 3 output signals from the clock (H/L for each bit output) goto the analog inputs on the robostix."

Perhaps you could clarify what it is you are trying to do.

It sounds to me like you are talking about a free running counter selecting the inputs for an analog multiplexer?

I guess that would work, except for the issue of the digital input, but I don't think it would be my first choice.

What "robostix" do you have? one I looked up seems to have "analog inputs" that can also be used a general purpose I/O, I'm not sure is they can be configured on a bit by bit basis, or if the whole port has to be configured the same. If it is bit by bit, since you have three available lines, if you configured two as outputs, you could use the two bits to multiplex 4 signals into the remaining line configured as an analog input. Then you just need an analog multiplexer chip, there are many available.

Well, I just checked a ATmega128 "summary" data sheet and see:

"Port F also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used."

That IF might be a problem, it sort of sounds like it is all or nothing for the analog ports, but one would have to check the full data sheet to be sure.