Spi begin failed with Rpi 3B+

[Chhour Vongchivorn]

Dear bcm2835

Before I used Rpi 3 B work with mcp3008 it works very well. but now I change to Rpi B+ but it fails with function bcm2835_spi_begin() . could you have any idea? 

thank you.

[Christian Kevin Alvarado Rimas]

Did you enable SPI interface in the raspi-config? if you didnt, follow this (for RPi 2,  i think it is pretty much the same for RPi B+)

$ sudo raspi-config

choose 

Interfacing Options

then

P4 SPI

that is it.
if the issue continues. Are you using Rasbian Stretch or Jessie or something Older? cause far far away, at the beginning of the times, in order to enable the SPI, you had to edit somefiles

Regards :¬D

[July Jim]

I am "porting" this "library" into C++,

During doing so I was wondering if setting GPIO to SPI pins ALT0 mode is really necessary if SPI is also "configured" in RPi.

So what does "raspi_config" actually do for SPI?

bcm2835_spi_begin as fas as I can tell only knows RPi2 and RPI1 , it has #define switch in the code to do so, no "B"  option.  Rpi2 is 2 and "higher".

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[Arjan van Vught]

Op 10 jun. 2018, om 01:22 heeft Christian Kevin Alvarado Rimas <cke...@gmail.com> het volgende geschreven:

Did you enable SPI interface in the raspi-config?

For al my Rasberry Pi models with all versions of Raspbian, I have always disabled I2C and SPI. This in order to prevent that the kernel module is interfering with the library.

- Arjan

http://www.raspberrypi-dmx.org

[Arjan van Vught]

Op 10 jun. 2018, om 04:02 heeft July Jim <tccio...@gmail.com> het volgende geschreven:

During doing so I was wondering if setting GPIO to SPI pins ALT0 mode is really necessary if SPI is also "configured" in RPi. 

So what does "raspi_config" actually do for SPI?

It always best not to rely on what is being provided by the environment (in this case Raspbian). Hence it is best to set the GPIO pins to the alternate function in our code. Hence we have full awareness and control of our environment.

The raspi-config can be used to activate the SPI/I2C kernel modules. Or for this library , enable the device tree.

- Arjan

https://github.com/vanvught/rpidmx512

[Arjan van Vught]

Op 10 jun. 2018, om 04:02 heeft July Jim <tccio...@gmail.com> het volgende geschreven:

I am "porting" this "library" into C++,

We can use the same in C++. It is no difference. I call all in the ‘init’ functions in a the constructor. For example -> https://github.com/vanvught/rpidmx512/blob/master/lib-l6470/src/slushboard.cpp#L73

- Arjan

http://www.raspberrypi-dmx.org 

[Chhour Vongchivorn]

in my case, I used the Rasbian stretch. follow your instructions I already open Spi configure. but I still the same problem. 

[Arjan van Vught]

Op 10-6-2018 om 16:37 schreef Chhour Vongchivorn:

in my case, I used the Rasbian stretch. follow your instructions I already open Spi configure. but I still the same problem. 

bcm2835_spi_begin returns 0 when  bcm2835_spi0 == MAP_FAILED  --> bcm2835_spi0 is set in bcm2835_init when bcm2835_init returns 1 (OK).

if (bcm2835_spi1 == MAP_FAILED)
      return 0; /* bcm2835_init() failed, or not root */

So we can expect that bcm2835_spi_begin fails when bcm2835_init failed before or is not called with root.

Please be aware that you must call bcm2835_init in each thread where you are using the library functions.

- Arjan

http://www.raspberrypi-dmx.org/

[Chhour Vongchivorn]

Thank everyone. Finally, I can solve it. 

have a good day !!!

[Arjan van Vught]

Op 11 jun. 2018, om 09:54 heeft Chhour Vongchivorn <chho...@gmail.com> het volgende geschreven:

 Finally, I can solve it. 

Please share the solution. Thanks.