ADC_SAR_SEQ Component using more macrocells than datasheet spec?

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KyTr_1955226
Level 6
Level 6
250 sign-ins 10 likes given 50 solutions authored

Hi all,

     I've got an issue with the ADC_SAR_SEQ component that I'd like to get to the bottom of.  I'm looking to replace a regular ADC_SAR component w/ a Sequential ADC_SAR (see Handling multiple analog inputs/polling rates using an Analog Mux/SAR ADC for the genesis of this issue).

With the standard ADC_SAR + AnaMux setup, my project weighs in at 123/192 Macrocells used.  This leaves me with 69 free.  The datasheet for the ADC_SAR_SEQ v2.0 claims for a default setup, the component uses 43 Macrocells.  When I attempt to actually build the ADC_SAR_SEQ into my project (deleting the original ADC_SAR), I am now over the limit at 199 Macrocells, which puts the ADC_SAR_SEQ at a whopping 76 Macrocells used.  Where is this huge discrepancy coming from?

ORIGINAL ADC_SAR:

ADC_SAR.png

ADC_SAR_Cfg.png

ADC_SAR_SEQ:

ADC_SAR_Seq.png

ADC_SAR_Seq_cfg.png

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

Hi Kyle and Brock,The datasheet specifies the use of 43 macrocells for default configuration.If component from the component catalog is placed to the Project schematic and input/output pins are connected without any configuration, it is called the default configuration. The macro cell usage for other configurations are not listed in the datasheet.

pastedImage_0.png

Best Regards,
VSRS

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

Hi Kyle,

This looks unusual. Will you be able to share both projects ? Are the projects exactly identical apart from the ADC ?

Best Regards,
VSRS

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Thanks for the reply,

I forgot to mention, the chip I am using is a CY8C5468AXI-LP106.

PSoC Creator 4.1 update 1

ADC_SAR_SEQ component v2.10

It is only one project, one in which I was just going to replace the SAR ADC with a Sequencing SAR ADC but ran into the aforementioned problem.

I can't share the entire project without jumping through a bunch of red tape, but I have been able to reproduce with a test project (attached).

The project consists only of 2 analog pins, the Sequencing SAR ADC, and an interrupt.  76 Macrocells are used by this project.

Let me know if there's any additional information needed.

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I have something similar on a design using a CY8C5888AXI-LP096 where a 7 input Sequencing SAR ADC uses 68 macrocells. I thought it may have something to do with the 7 inputs, but a 2 input mux also uses 68 macrocells.

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

Hi Kyle and Brock,The datasheet specifies the use of 43 macrocells for default configuration.If component from the component catalog is placed to the Project schematic and input/output pins are connected without any configuration, it is called the default configuration. The macro cell usage for other configurations are not listed in the datasheet.

pastedImage_0.png

Best Regards,
VSRS

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Well that explains why there is a difference, so I'll mark as the answer, but I'm still a bit bothered that going from Differential to Single Ended results in the size of the component bloating out to 76% above the original specified size.

So how am I to handle multiple single-ended analog inputs without eating nearly 40% of my hardware in the process?

I made a thread prior to this one detailing how I did this via an Analog Mux and SAR ADC, but I question my method, and feel like there must be a more elegant solution that I'm missing:

Handling multiple analog inputs/polling rates using an Analog Mux/SAR ADC

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