[sdiy] nice Digi Pot

[jays at aracnet.com]

That should of been 200us.

Jay S.
On 2016-06-27 14:48, jays at aracnet.com wrote:
> 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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