PSOC4 Seq Sar Adc Limits

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Anonymous
Not applicable

The spec says about 4 diff channels or 8 single.

   

It's possible to connect an analog multiplexer and a SAR in a Psoc4?

   

I've tested with no sucess, (error between mux and sar mux) but I guess if I'm doing something bad.

   

Best regards.

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ETRO_SSN583
Level 9
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I was able to route this -

   

 

   

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Anonymous
Not applicable

Only 1 channel is possible in ADC for putting a Mux before.

   

Thanks a lot.

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ETRO_SSN583
Level 9
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Tried this and it would NOT route -

   

 

   

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Anonymous
Not applicable

 Sorry, last reply was a question:

   

Is possible putting a mux previous to the SAR (and only one), if there is only one channel in SAR?

   

 

   

Best regards.

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ETRO_SSN583
Level 9
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The first example I posted is SAR at 1 channel, external 4 channel mux to SAR

   

as its input. That would route without error. Maybe I still do not understand the

   

question ?

   

 

   

Regards, Dana.

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RodolfoGL
Employee
Employee
250 solutions authored 250 sign-ins 5 comments on KBA

Hi, one way to do is to add a OpAmp_1 between the Analog Mux and the ADC SAR.

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If you can't use the OpAmp, you could manually connect the first Pin to the first channel. Then use the PORT_SELX switches to connect the desired port to the Global Analog Bus.

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rola_264706
Level 8
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I just tried this and with the Psoc 4 you can't use a mux and a ADC_SAR_SEQ at the same time also why would you want to do this as you have lots of channels in the ADC_SAR_SEQ. If you try your Mux and ADC_SAR_SEQ you  get an over flow in the Analog channel routing.

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rola_264706
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Here is an example. !

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RodolfoGL
Employee
Employee
250 solutions authored 250 sign-ins 5 comments on KBA

Hi. There are a few reasons you might want to use the analog mux in combination with the SAR SEQ.

1. You need more than the number of channels supported by the SAR SEQ.

2. You want to have a smaller sample rate for the "Analog Muxed" channels, but keep the sample rate for the "Sequenced SAR Channels".

3. You want to increase the impedance input buffer for the SAR ADC by adding an OpAmp (as the example above).

PSoC Creator will not allow you to connect the Analog Mux directly to the SAR SEQ when configured with multiple channels. However, you can manually mux the channels to connect to the Global Analog Mux. Just make sure to connect a non-PORT2 to the desired channel.

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