PSoC 4 BLE Using AMux with OpAmps

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Jaleh
Level 1
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5 replies posted 5 sign-ins First reply posted

Hi,

In my project I have 7 Opamps but due to the limits of using Opamps in PSoC 4 BLE (we can just use 4 of them), I am using Amuxs to select the inputs of those Opamps, but for the Opamps which are in operational mode I receive the following error:

"Failed to route net "Net_12". Error: No valid route exists Ports: vout
vminus
muxin_0
analog_term
muxin_1
analog_term
vout
vminus
Sources: PASS0.CTB0.OA1.vminus
USERIO DiffAmp_minus(0)
USERIO Pin_2(0)
Targets: PASS0.CTB0.OA1.vminus"

The error is just for the Opamp not in the buffer mode.

I attach the scheme of my project.

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Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi,

The AMUXBUS used to route these inputs is a limited resource. Only 2 buses are available for the device. So if you are are trying to route more inputs than that the routing is expected to fail. May be you have to go for a time shared basis of the 2 opamp resources in that case and make sure that you are not exhausting the resources.

Best Regards,
Vasanth

Best

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12 Replies
Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi,

The AMUXBUS used to route these inputs is a limited resource. Only 2 buses are available for the device. So if you are are trying to route more inputs than that the routing is expected to fail. May be you have to go for a time shared basis of the 2 opamp resources in that case and make sure that you are not exhausting the resources.

Best Regards,
Vasanth

Best

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Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

Jaleh,

Does this configuration work for you?

This configuration doesn't flag any errors in the Application build phase.

Len_CONSULTRON_0-1622642991108.png

If not, this also flags no errors.

Len_CONSULTRON_1-1622643227607.png

 

Len
"Engineering is an Art. The Art of Compromise."
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@Len_CONSULTRON wrote:

Jaleh,

Does this configuration work for you?

This configuration doesn't flag any errors in the Application build phase.

Len_CONSULTRON_0-1622642991108.png

If not, this also flags no errors.

Len_CONSULTRON_1-1622643227607.png

Hi,

Yes but I need Mux in both inverter and non-inverter inputs.


 

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Jaleh,

Can you be more specific?

The way your original schema depicted, you could have the following input sensing configurations through Op2:

  • DiffAmp_plus and DiffAmp_minus
  • DiffAmp_plus and Pin_2
  • Pin_1 and DiffAmp_minus
  • Pin_2 and Pin_2.

Do any of these configurations not make sense in your application?

Len
"Engineering is an Art. The Art of Compromise."
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Jaleh
Level 1
Level 1
5 replies posted 5 sign-ins First reply posted

What I need is the configuration in the op2, but this configuration has error and I am looking for an alternative, but I can't use more Opamps, because I already have 3 of them. 

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Jaleh,

You have 4 Opamps available to the 4200 BLE part.

You still didn't answer my question:

The way your original schema depicted, you could have the following input sensing configurations through Op2:

  • DiffAmp_plus and DiffAmp_minus
  • DiffAmp_plus and Pin_2
  • Pin_1 and DiffAmp_minus
  • Pin_2 and Pin_2.

Do any of these configurations not make sense in your application?

Len
"Engineering is an Art. The Art of Compromise."
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Yeah PSoC 4 has 4 Opams and this is why I am using a mux, because I actually need 7. And no, that doesn't make any sense to me, I attach again the part of the problem which I am trying to solve and not by adding another Opamp because I don't have any available.

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Jaleh,

You have 4 opamps available but you are using only 3 Opamps in your configuration.

The input configuration I detailed

  • DiffAmp_plus and DiffAmp_minus
  • DiffAmp_plus and Pin_2
  • Pin_1 and DiffAmp_minus
  • Pin_2 and Pin_2.

is what you would have available if you could route the AMuxes as you defined.

Maybe we need to approach this differently.

IF you had 7 opamps available, what would it look like from the inputs?   My goal is to try to provide you routable configuration on the 4200 BLE that is equivalent to your desired 7 opamp solution.  It may require using ALL 4 opamps.

Len
"Engineering is an Art. The Art of Compromise."
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Jaleh
Level 1
Level 1
5 replies posted 5 sign-ins First reply posted

Here is the complete image, but it isn't important because I have already explained my problem which is using mux with Opamps in operational mode not in follower mode.

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Jaleh,

I see from your new pic of your schema that you are using all 4 opamps.  

Can you provide your theoretically 7 opamp solution.

Your use of Amuxes for Op2 appears to be the problem.  There may be another solution but I need to know which input combinations do you need to support for Op2.

Len
"Engineering is an Art. The Art of Compromise."
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Jaleh,

You appear to have all the Opamp outputs used as external.   They don't appear to used internally.

Is it possible that one or more of the Opamps are actually being used in a comparator mode?  If so,

there are 2 low-power Comparators in addition to the 4 Opamps.

Len
"Engineering is an Art. The Art of Compromise."
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Yes, the circuit is complicated and all the pins you see are external and no, I can't use comparator.

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