[TriEmbed] Using SPI

[Rodney Radford]

If you could offer more details about the problem you are trying to solve,
we could be more help.

I think your latest question (or concern) is that sending out independent
SPI commands to motor controllers would be offset enough in time (since
with one SPI bus you can only send one command at a time) will be an
issue.  If you were to send one message out to one motor, then another to
the second, etc - anywhere near the speed capable of SPI, you are talking
about less than a millisecond total time for a half dozen (or more) easily
and that is small enough that you will not be able to tell the difference.

If I have misunderstood the problem, or there are other unknowns I have not
described here, please update - but you should easily be able to control
multiple SPI motors with the same bus with no issue.



On Tue, Apr 1, 2014 at 10:29 PM, Carl Nobile <carl.nobile at gmail.com> wrote:

> Thanks Rodney,
>
> What I'm trying to do is control 4 (or more) motor controllers through SPI
> using the SS (Slave Select) pin. But I just though of an issue, I would
> never be able to send all the motors a command simultaneously using this
> method. I'd have to got down the list of motors that were online at the
> time and send what might be the same command like 'stop' one motor at a
> time. It would be quick, so may not be an issue, but I wonder if there is a
> better way of doing this.
>
> Carl
>
>
>
> On Tue, Apr 1, 2014 at 9:46 PM, Rodney Radford <ncgadgetry at gmail.com>wrote:
>
>> The two data lines MISO and MOSI can be in any state until the falling
>> edge of SCLK, so they could conceivably be used for other purposes.
>>
>> In addition, if the only concern is programming the hex image (which is
>> not something you do while the motors are running), you could have some
>> jumpers that disconnect the SPI lines from the rest of the circuit while
>> downloading the image, and then put them back in place for normal operation.
>>
>>
>>
>> On Tue, Apr 1, 2014 at 9:40 PM, Carl Nobile <carl.nobile at gmail.com>wrote:
>>
>>> Hi all,
>>>
>>> Is it possible to use the SPI pins on a mircorcontroller for two
>>> purposes? For example used to burn the hex image and when not burning the
>>> image then in normal running mode used to control motor speed, etc. or
>>> something similar. My guess is yes, but I haven't figured out how to do it.
>>>
>>> Carl
>>>
>>>
>>> _______________________________________________
>>> Triangle, NC Embedded Computing mailing list
>>> TriEmbed at triembed.org
>>> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
>>> TriEmbed web site: http://TriEmbed.org
>>>
>>>
>>
>
>
> --
>
> -------------------------------------------------------------------------------
> Carl J. Nobile (Software Engineer)
> carl.nobile at gmail.com
> -------------------------------------------------------------------------------
>
>
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