PSoC4 ADC input External analog multiplexer

[chme_4646286]

Hi，

Referring to the PSoC4100S Plus series datasheet, its ADC input supports only 8 channels at most.

Is there a multiplexer selection function inside the ADC Core to meet the expansion of input channels?

Or are there other solutions to expand ADC sampling channels?

[Arpit_S]

Hi,

Port 2 is the dedicated port for ADC, so from there you get 8 Channels. Also, you get two more channels from AMUXBUS A and AMUXBUS B as shown in the image. In addition to that, 2 more channels you can get from the Op-Amp (Notice sarbus0 and sarbus1). This way you can get 12 Channels.
Apart from that, if you want further more input channels, through AMUX bus, we can dynamically change the inputs and can get further more channels. First connect AMUX A and AMUX B to some pin (say P3.7 and P3.6) then after the data has been sent to ADC through these pins, then you have to put them in waiting using some delay and then connect AMUXBUS A and AMUXBUS B to another set of pins and then they'll become the input channels. This way you can increase number of channels but due to waiting/delay the output may not be completely correct.

Can you please share which development environment are you using? PSoC Creator or ModusToolbox?

Thanks & Regards

Arpit Srivastav

[chme_4646286]

Hi Srivastav;

I am using PSoC Creator 4.4;

Based on the method you mentioned, are there any examples to refer to?

In the actual project, 10 or 12 inputs are required

thanks very much~~

[DennisS_46 · Accepted solution]

The chip has 8 dedicated SAR inputs, but you can route any number of signals onto the analog mux bus and
connect that into the SAR. I built a simple example of a 20 input SAR:

It routes cleanly. Because you've gone past 8 inputs, the auto-sequencing part of the SAR doesn't work.
You'll have to write the mux address then get the ADC sample separately for each input.
---- Dennis Seguine, PSoC Applications Engineer