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CAPSENSE™ & MagSense

StOl_4093121
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Hello,

We released a board that uses the CY8C4147AZI-S475 controller to measure capacitance readings from 5 sensors. We look at the actual count value for our application and a problem has come up when we started to produce more boards. basically certain boards read far lower count values for certain sensors than others when reading the same capacitance. So far we've only seen cases where one or two sensors out of the five are reading lower. For example, a "good" board will read 960 counts, and if I apply the same capacitance to the "bad" board will give me 580 counts.

Any ideas on why it would be so inconsistent? Could it be manufacturing issues or something like that? I wouldn't think the PSOC controller itself would have that kind of variation chip to chip.

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ncbs
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Hi @StOl_4093121,

Refer to "CapSense Performance Tuning" chapter in the PSoC® 4 and PSoC 6 MCU CapSense® Design Guide. The raw counts might slightly vary considering various factors such as presence of foreign metallic objects, overlay, usage of filters, etc.

If the sensors are tuned for an SNR of more than or equal to 5:1, then the performance will be acceptable.

 

Regards,
Nikhil

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ncbs
Moderator
Moderator 250 sign-ins 250 replies posted 100 solutions authored
Moderator

Hi @StOl_4093121,

Refer to "CapSense Performance Tuning" chapter in the PSoC® 4 and PSoC 6 MCU CapSense® Design Guide. The raw counts might slightly vary considering various factors such as presence of foreign metallic objects, overlay, usage of filters, etc.

If the sensors are tuned for an SNR of more than or equal to 5:1, then the performance will be acceptable.

 

Regards,
Nikhil

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ncbs
Moderator
Moderator 250 sign-ins 250 replies posted 100 solutions authored
Moderator

Hi @StOl_4093121 ,

Tuning of the sensors will ultimately decide the raw counts being generated by the sensors. PSoC devices/controllers are thoroughly checked/tested before market release, hence it is highly unlikely for chip-to-chip variation to occur.

Regards,
Nikhil

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