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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