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hello all, 
can you pls tell me maximum how many devices can be connected to
controller using SPI? 
like in i2c maximum devices are 128. so pls tell me the number and
how? 
thank you 
regards 
 </description><dc:language>en-US</dc:language><generator>Telligent Community 10</generator><item><title>RE: spi</title><link>https://community.arm.com/thread/78686?ContentTypeID=1</link><pubDate>Tue, 28 Sep 2010 23:23:15 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:3966f00a-8688-4130-8af4-b026d425af28</guid><dc:creator>kppp kpp</dc:creator><description>&lt;p&gt;&lt;p&gt;
hello sir,&lt;br /&gt;
thanks for reply. i read SPI document and i knew that depending upon
NSS lines slaves are interfaced. but i wanted to confirm and have
other opinions of people and it is not mentioned in document clearly
about salve numbers.&lt;br /&gt;
anyways, thanks for your instant reply and clearing my doubts&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: spi</title><link>https://community.arm.com/thread/65912?ContentTypeID=1</link><pubDate>Tue, 28 Sep 2010 22:26:01 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:e5a3e14a-5648-45ef-8c50-14b6474152e0</guid><dc:creator>ImPer Westermark</dc:creator><description>&lt;p&gt;&lt;p&gt;
No we can&amp;#39;t. Why? Because there is no magically &amp;quot;correct&amp;quot;
figure.&lt;/p&gt;

&lt;p&gt;
I2C contains addressing, so the figure you have seen relates to
addressing of devices.&lt;/p&gt;

&lt;p&gt;
SPI uses separate signals for slave-select. If you use 4
slave-select lines you can address four slaves. If you use 19
slave-select pins you can address 19 slaves.&lt;/p&gt;

&lt;p&gt;
If you only send data in one direction - master-to-slave - you can
have multiple SPI slaves connected and addressed at the same time
using a single slave-select line.&lt;/p&gt;

&lt;p&gt;
In the end, the number of slaves possible depends on two
things:&lt;br /&gt;
- how much hardware you can dedicate to the addressing of the
slaves&lt;br /&gt;
- how much capacitance you have on the signals and your used bit rate
- i.e. what load you can put on the signal wires and still maintain
the required signal integrity.&lt;/p&gt;

&lt;p&gt;
You have read up on SPI before you did ask your question, haven&amp;#39;t
you?&lt;/p&gt;
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