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Re: [PATCH v3 2/2] misc/pca9552: Let external devices set pca9552 inputs
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From: |
Andrew Jeffery |
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Subject: |
Re: [PATCH v3 2/2] misc/pca9552: Let external devices set pca9552 inputs |
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Date: |
Fri, 27 Oct 2023 16:38:48 +1030 |
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User-agent: |
Evolution 3.46.4-2 |
On Tue, 2023-10-24 at 13:11 -0500, Glenn Miles wrote:
> Allow external devices to drive pca9552 input pins by adding
> input GPIO's to the model. This allows a device to connect
> its output GPIO's to the pca9552 input GPIO's.
>
> In order for an external device to set the state of a pca9552
> pin, the pin must first be configured for high impedance (LED
> is off). If the pca9552 pin is configured to drive the pin low
> (LED is on), then external input will be ignored.
>
> Here is a table describing the logical state of a pca9552 pin
> given the state being driven by the pca9552 and an external device:
>
> PCA9552
> Configured
> State
>
> | Hi-Z | Low |
> ------+------+-----+
> External Hi-Z | Hi | Low |
> Device ------+------+-----+
> State Low | Low | Low |
> ------+------+-----+
>
> Signed-off-by: Glenn Miles <milesg@linux.vnet.ibm.com>
Reviewed-by: Andrew Jeffery <andrew@codeconstruct.com.au>