On 16/07/14 17:08, geetha wrote:
> I am new to Beaglebone & not too familiar with Linux.
>
> My application requires data to be acquired from a device on SPI &
> transmit it on LAN.
>
> I am using the preloaded Angstrom OS.
>
> I have setup the environment for development by precisely following
>
> http://jkuhlm.bplaced.net/hellobone/
>
> With this platform, I am able to develop application for LAN transmission.
>
> For SPI interface I have followed
>
> http://elinux.org/BeagleBone_Black_Enable_SPIDEV
>
> I have to use SPI0. I am able to reach properly upto the step of
> compiling & running the spidev_test code. Following are my questions
>
> 1. Does the preloaded Angstrom has SPI device built in the
> kernel or should the kernel be rebuilt by including the spidev.c?
Yes, SPI is included in the Angstrom kernel.
> 2. Will the gcc libraries compile the SPIdev_test code? I
> am getting ‘undefined error for SPI_TX_QUAD’ and many more which I
> am finding defined in spi.h which is not in gcc include. Can I
> simply copy spi.h file into the include directory and compile?
Where did you get spidev.c from? You must use the same source as the
kernel; if you use a newer source it may not compile with the older
version of the kernel you are using.
> 3. With reference to the below segment in the .dts file,
> sclk is mentioned as input. However, I would like BBB to be master
> to generate clock for the external device. In such case, should the
> change the value to 0x10?
No, this a "quirk" with the spi driver, the clock is set as INPUT but it
will also OUTPUT on the pin.
>
> 4. fragment@0 {
>
> 5. target = <&am33xx_pinmux>;
>
> 6. __overlay__ {
>
> 7. spi0_pins_s0: spi0_pins_s0 {
>
> 8. pinctrl-single,pins = <
>
> 9. 0x150 0x30 /* spi0_sclk, INPUT_PULLUP | MODE0 */
>
> 10. 0x154 0x30 /* spi0_d0, INPUT_PULLUP | MODE0 */
>
> 11. 0x158 0x10 /* spi0_d1, OUTPUT_PULLUP | MODE0 */
>
> 12. 0x15c 0x10 /* spi0_cs0, OUTPUT_PULLUP | MODE0 */
>
> 13. >;
>
> 14. };
>
> 15. };
>
> 16. };
>
> 4. The pin mapping file shows that the SPI pins are mapped to 84,…..
> How to verify that it has been correctly mapped to the processor pin number.
This data can be found in the am335x TRM; you have to find the pinctrl
register in the TRM and then match the offset 0x150 to the table and
double check that it is SPI.
>
> Request help for these trivial questions.
>
> Thanks
>
--
Jack Mitchell ([email protected])
Embedded Systems Engineer
Cambridgeshire, UK
http://www.embed.me.uk
--
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