Gah! Data sheets.

Sep 26, 2024 Last reply: 1 year ago 3 Replies

I was looking at building a remote controlled volume control for use at home. Probably won't happen, but I came across this device:



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Page 7 gives the serial protocol. It mentions S and P bits, but as far as I can see they're nowhere else defined.



Further down the page, it describes an auto-increment function. That is the only mention.



At the bottom of the page it talks about the consequence of an audio signal being inputted (sic) before (during?) power on. Hard to know exactly what the intent is, but based on that, I'd be concerned that the device might latch up, or otherwise misbehave, if there's any input before power on. Be great to build a bunch of boards with this and then discover that some proportion are flaky.



How many designers would conclude that this could be more trouble than it's worth, and find something else?



Sylvia.


S and P are no bits but the start and end conditions of the i2c protocol.

Hard to know what to do if the hardware misbehaves. Even if one can get another device to let go of the data line, and stop messing with the clock, one still doesn't know what its internal state is.

Not that I have any experience of doing this. I've only once got the point of dealing with physical I2C hardware, and it behaved as expected, at least for the time I was trying it.

Either way, if I had to design something, I would avoid as far as possible creating a multi-master system, even at the cost of higher complexity elsewhere, and if no slave device was even capable of clock-stretching, I'd be much happier.

Sylvia.

We need two web sites, icbugs.com and stupiddatasheets.com.

Seriously. They could be popular and profitable.

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