2009-04-29 23:23:54     is it possible two or more spi devices working at the same time?

Document created by Aaronwu Employee on Aug 15, 2013
Version 1Show Document
  • View in full screen mode

2009-04-29 23:23:54     is it possible two or more spi devices working at the same time?

david wang (CHINA)

Message: 73454   

 

Hi, all

 

  I 've two devices using spi , one is spi_mmc, the other is spi wi-fi module. Each of them have differrent spi chip select signal and share the other spi pins. Is it possible running two devices at the same time? Thanks!

 

 

QuoteReplyEditDelete

 

 

2009-04-30 00:11:20     Re: is it possible two or more spi devices working at the same time?

Mike Frysinger (UNITED STATES)

Message: 73455   

 

the entire point of SPI is that all pins are shared except for the chip select, so you should be able to use as many SPI devices as you have chip selects

 

you will however need svn trunk kernel as there have been many fixes for both those types of devices in trunk-only

 

i dont know what kind of performance you'll see though if you attempt to use the filesystem heavily while doing network traffic at the same time

QuoteReplyEditDelete

 

 

2009-04-30 01:14:48     Re: is it possible two or more spi devices working at the same time?

david wang (CHINA)

Message: 73456   

 

Hi, Mike

 

  Do you mean if I svn the newest kernel, I'll get the spi wi-fi module and spi mmc card work together?

 

  We plan to transfer video pictures through the wi-fi module all the time after the board bootup, while using the spi mmc card in need, I think it's not a heavy work for the filesystem.

QuoteReplyEditDelete

 

 

2009-04-30 02:35:13     Re: is it possible two or more spi devices working at the same time?

Mike Frysinger (UNITED STATES)

Message: 73458   

 

i'm saying the last release will almost certainly not work but trunk most likely will.  but we've never tested a spi wifi and spi mmc simultaneously, just independently.

QuoteReplyEditDelete

 

 

2009-05-02 00:05:28     Re: is it possible two or more spi devices working at the same time?

david wang (CHINA)

Message: 73519   

 

Hi, Mike

 

  I checked the forum, It seems that no people has tested it, am I right?  Then, I'd like to know if it is possible to run the two module running simultaneously  even in theory.Thanks!

QuoteReplyEditDelete

 

 

2009-05-04 10:46:12     Re: is it possible two or more spi devices working at the same time?

Wolfgang Muees (GERMANY)

Message: 73571   

 

The MMC driver is using the SPI device for long periods of time. If you have anything parallel which tight reaction times, it will fail.

 

I our current project, we use the spi exclusive for mmc, and use an external SPI device in a CPLD for the rest.

 

regards

 

Wolfgang

Attachments

    Outcomes