[sdiy] nice Digi Pot

[jays at aracnet.com]

Off the top of my head the only thing that I can think of is the amount 
of time to do the operation.

Let's say if you have 64 byte message you need to send out it will take 
longer than just a single byte. That time maybe longer than what you 
need to refresh the device you are talking to. An example would be if 
you need to refresh a DAC every 100us and it takes 20us to write 64 
bytes of data. There are other things that are a factor too. Like do you 
have DMA, overhead of the bus you're using, clock rates and so on.

I haven't ran across any SPI or I2C devices out there that do daisy 
chaining and I've used a fair number. A lot of the FPGA chips I've had 
to deal with do this do and some of the 'smart' LEDs do daisy chaining. 
Are there any SPI/I2C chips out there that people know about?

Thanks
Jay S.


On 2016-06-27 13:42, Vladimir Pantelic wrote:
> On 27.06.2016 22:17, rsdio at audiobanshee.com wrote:
>> Daisy-chaining is rarely necessary. Usually, it's just a waste of a 
>> pin. If
> 
> what pin does it waste? sorry, I do not follow.
> 
>> your main processor's MOSI has sufficient fan-out, you can simply 
>> connect it
>> directly to the input of every SPI slave. If the fan-out is weak, then 
>> an
>> external buffer will suffice.
> 
> and how do I address every individual slave?
> 
>> The only time daisy-chaining is really useful is when you have a
>> serial-to-parallel converter, and you want downstream parallel devices 
>> to
> 
> daisy chaining is useful when I want to control a lot of similar
> devices from a single SPI connection, why would I not want that?
> 
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