2009-01-18 06:37:37     SPI testing

2009-01-18 06:37:37     SPI testing

ivan ucles (GERMANY)

Message: 68066   

Hi,

I try to send SPI messages between a CM-BF537 board and a STAMP 537 board without succes so far.

In both boards i´ve added the bfin5xx driver and the spidev driver. And i have initialize a device on bus "0"

and CS "1" spidev0.1.

I connect MOSIs, MISOs and  CLKs of both boards.

The CM-BF537 is supposed to be the master, so i connect de SSEL chip to 5v. and its CS1 to the SSEL chip

of the STAMP.

When i try to send a message using the example included in spidev kernel documentation, i get

response(2, 3): ff ff

What am i missing? could somebody help me?

Thank u

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2009-01-18 10:12:07     Re: SPI testing

Robin Getz (UNITED STATES)

Message: 68068   

Ivan:

Just to make sure -- SPI is a master/slave type set up. only one controlls the clock (connect CLKS together) - Master Out (MOSI) needs to be connected to Slave In (MOSI), and Master In (MISO) needs to be connected to Slave Out (MISO).

Plus - the Blackfin is a 3.3V device ONLY - 5V may damage the part.

-Robin

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2009-01-18 12:52:20     Re: SPI testing

Mike Frysinger (UNITED STATES)

Message: 68070   

also, the linux kernel does not support slave mode operation.  so if you want to have one be a slave, you'll have to write your own driver or extend the existing framework.

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2009-01-18 15:09:39     Re: SPI testing

ivan ucles (GERMANY)

Message: 68072   

Ok,

thanks for the answer.

Where could i find some information about how to write the slave-part driver?

Could i take another similar driver as template? which one?

About the voltage, i connected SSEL to another pin29 of x8 connector.

Should i connect it then to pin number 9 which is 3.3v right?

Thank you!

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2009-01-18 15:39:31     Re: SPI testing

Mike Frysinger (UNITED STATES)

Message: 68074   

unfortunately, there isnt much info as i dont think anyone has thought too hard on the idea.  might be easier to start out with a simple char driver and program the SPI controller yourself.

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2009-01-19 03:17:28     Re: SPI testing

ivan ucles (GERMANY)

Message: 68085   

And if i configure both boards as master (with both SSEL to  3.3v and no CS)

can they interchange messages? throug which device?

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2009-01-19 03:20:58     Re: SPI testing

Mike Frysinger (UNITED STATES)

Message: 68086   

like Robin said, only one device can be the master at any one time.  that is simply how SPI works.

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