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Title: SPI devices
Post by: Arjan on October 27, 2012, 01:45:52 PM

Hi,

How many SPI /CS lines are available on the UEXT connector?
Are the /dev/spidevA.B devices available for the same?

Thanks. Regards, Arjan

Title: Re: SPI devices
Post by: LubOlimex on October 29, 2012, 09:21:10 AM

Hello Arjan,

Please check the following three links, which contain great deal of information about UEXT:

http://en.wikipedia.org/wiki/UEXT (http://en.wikipedia.org/wiki/UEXT)
https://www.olimex.com/Products/Modules/UEXT/ (https://www.olimex.com/Products/Modules/UEXT/)
https://www.olimex.com/Products/Modules/UEXT/resources/UEXT_rev_B.pdf (https://www.olimex.com/Products/Modules/UEXT/resources/UEXT_rev_B.pdf)

Regards,
Lub/OLIMEX

Title: Re: SPI devices
Post by: Arjan on October 31, 2012, 05:52:51 PM

Thanks Lub.

It seems that there is just one SPI Slave Select line on the UEXT.

I have three SPI slaves (MCP49x2) which I need to address.

Is it possible to use PIN 5 and PIN 6 as general output PINs?

Then using PIN 5/6 with PIN 10 (SPI Slave Select) and a 74HC139 would enable me to address more slaves.

Thanks.
Regards, Arjan

Title: Re: SPI devices
Post by: olimex on October 31, 2012, 06:23:30 PM

Hi
UEXT have just one SPI and it's very bad idea to use the other interfaces for chip select
the new modules we do all have PIC16F1503 which is small and neat device which can re-configure it ports and do some logic in between them.
So what we do is I2C to address the device (i.e. rise CS) then use SPI UART etc of the device selected (addressed) with the I2C.
this is nice and clean way to interface many modules on UEXT which share same interface
Tsvetan

Olimex Support Forum

Others => UEXT => Topic started by: Arjan on October 27, 2012, 01:45:52 PM