mcp2515 overlay support to SPI bus 1 on RPI 3

[ahmedawad1]

I tested the additional spi bus 1 on RPI3 after enabling the overlay in config.txt file

dtoverlay=spi1-3cs

the 3 chip selects spi1.0 / spi1.1 / spi1.2, all works fine with an mcp3008 ADC chip, so there is no problem at all with this bus and its corresponding chip selects.

Now, I wanted to write .dts source that supports the functionality of mcp2515 on this additional SPI bus. Very similar to what a contributor before did @petit_miner to the overlay mcp2515-can1-overlay.dts but i changed every spi0 to spi1, the mcp2515 worked but spi0.1 disappeared and the chipselects of "SPI 1" were not properly functioning, that is if connecting the mcp2515 module to spi1.0 or spi1.1 they both works which is not right.

here is my trial, i didn't change much except using spi1 instead of spi0.

the original dts file is found on your repository rpi-4.4.y , this is what i used to modify and recompile

My modifications are:
`

 /*
 * Device tree overlay for mcp251x/can2 on spi1.0
 */
/dts-v1/;
/plugin/;

/ {

	compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";
	/* disable spi-dev for spi1.0 */
	fragment@0 {
		target = <&spi1>;
		__overlay__ {
			status = "okay";
		};
	};

	fragment@1 {
	target = <&spidev0>;
	__overlay__ {
		status = "disabled";
	};
	};

	/* the interrupt pin of the can-controller */
	fragment@2 {
		target = <&gpio>;
		__overlay__ {
			can2_pins: can2_pins {
				brcm,pins = <25>; /* it is the default pin and it will be overriden */
				brcm,function = <0>; /* input */
			};
		};
	};

	/* the clock/oscillator of the can-controller */
	fragment@3 {
		target-path = "/clocks";
		__overlay__ {
			/* external oscillator of mcp2515 on SPI1.0 */
			can2_osc: can2_osc {
				compatible = "fixed-clock";
				#clock-cells = <0>;
				clock-frequency  = <16000000>;
			};
		};
	};


	/* the spi config of the can-controller itself binding everything together */
	fragment@4 {
		target = <&spi1>;
		__overlay__ {
			/* needed to avoid dtc warning */
			#address-cells = <1>;
			#size-cells = <0>;
			can2: mcp2515@0 {
				reg = <0>;
				compatible = "microchip,mcp2515";
				pinctrl-names = "default";
				pinctrl-0 = <&can2_pins>;
				spi-max-frequency = <10000000>;
				interrupt-parent = <&gpio>;
				interrupts = <25 0x2>;
				clocks = <&can2_osc>;
			};
		};
	};
	__overrides__ {
		oscillator = <&can2_osc>,"clock-frequency:0";
		spimaxfrequency = <&can2>,"spi-max-frequency:0";
		interrupt = <&can2_pins>,"brcm,pins:0",<&can2>,"interrupts:0";
	};
};

`
please what i am doing wrong or what needs to be changed in order to have the mcp2515 overlay correctly uses the spi1.0 / spi1.1 / spi1.2 overlays.

Thanks

I am using Raspbian: Linux raspberrypi 4.4.38-v7+ #938 SMP Thu Dec 15 15:22:21 GMT 2016 armv7l GNU/Linux

[pelwell]

the mcp2515 worked but spi0.1 disappeared

That's would make sense if you meant "spi0.0", due to fragment@1 - spidev0 is the label for the node that creates spidev0.0, and fragment 1 disable it; just delete fragment 1.

the chipselects of "SPI 1" were not properly functioning

You will need to disable the spidev associated with spi1.0 - you can do this with an overlay parameter:

dtoverlay=spi1-3cs,cs0_spidev=off

Also, fragment 0 is unnecessary because loading the spi1-3cs overlay enables spi1.

In summary:

1. Delete fragments 0 and 1 (and renumber the others to be neat).
2. Change dtoverlay=spi1-3cs to dtoverlay=spi1-3cs,cs0_spidev=off.
3. Reboot and see what happens.

However, see #1484 - it seems that there are interrupt problems when various Aux peripherals (SPI1, SPI2 and UART1) are used together. You may have to disable (or not enable) UART1 - put enable_uart=0 in config.txt, or just don't add enable_uart=1. Alternatively, if you do need a serial port and you can live without Bluetooth for a the experiments, add dtoverlay=pi3-disable-bt to config.txt which tells the Pi3 to use UART0 (ttyAMA0) for console output, just like a Pi2.

I'm hoping to look at the Aux interrupt issue today.

[ahmedawad1]

This is incredibly awesome @pelwell . Thank you very much.

I had now SPI0 along with SPI1 working without any issues and i did not disable the UART at all. For the moment i don't need either UART1 or the Blutooth.

I have tested also the mcp2515 Transceiver on the whole chip selects of SPI1 with different overlays and it worked fine.

Just a matter of curiosity, you mentioned SPI2 but actually the SPI 2 bins are assigned to bins which don't exist for the 40 bins RPI3, is this considered for future RPI versions?
is it possible to change the brcm bins in the dts and have SPI 2 assigned to different pins ?

I am grateful to your help and Thank you again !

Regards
Ahmed

[pelwell]

SPI2 can be used on a Compute Module on GPIOs 40-45, but sadly the SPI2 function isn't available on GPIOS 0-27.

[ahmedawad1]

Thank you !

[karu2003]

Hi ahmedawad1
Share please the final Result.
I use three SPI SPI0.0 SPI0.1 and SPI1.0 for the MCP2515.
Thank you.

[ahmedawad1]

It is exactly as what what @pelwell mentioned in the summary steps. Follow the dts source code in the first comment, and make the required modifications. Then use a dtc compiler to compile from .dts to dtb or .dtbo according to the Raspbian kernel version that you use. You can see this post on the Raspberry Forum to get to know how to compile it from .dts source file. here

[karu2003]

I make mcp2515-can2-overlay.dts

/*

• Device tree overlay for mcp251x/can2 on spi1.0
  */
  /dts-v1/;
  /plugin/;

/ {

compatible = "brcm,bcm2835", "brcm,bcm2836", "brcm,bcm2708", "brcm,bcm2709";
/* disable spi-dev for spi1.0 */

/* the interrupt pin of the can-controller */
fragment@0 {
	target = <&gpio>;
	__overlay__ {
		can2_pins: can2_pins {
			brcm,pins = <25>; /* it is the default pin and it will be overriden */
			brcm,function = <0>; /* input */
		};
	};
};

/* the clock/oscillator of the can-controller */
fragment@1 {
	target-path = "/clocks";
	__overlay__ {
		/* external oscillator of mcp2515 on SPI1.0 */
		can2_osc: can2_osc {
			compatible = "fixed-clock";
			#clock-cells = <0>;
			clock-frequency  = <16000000>;
		};
	};
};


/* the spi config of the can-controller itself binding everything together */
fragment@2 {
	target = <&spi1>;
	__overlay__ {
		/* needed to avoid dtc warning */
		#address-cells = <1>;
		#size-cells = <0>;
		can2: mcp2515@0 {
			reg = <0>;
			compatible = "microchip,mcp2515";
			pinctrl-names = "default";
			pinctrl-0 = <&can2_pins>;
			spi-max-frequency = <10000000>;
			interrupt-parent = <&gpio>;
			interrupts = <25 0x2>;
			clocks = <&can2_osc>;
		};
	};
};
__overrides__ {
	oscillator = <&can2_osc>,"clock-frequency:0";
	spimaxfrequency = <&can2>,"spi-max-frequency:0";
	interrupt = <&can2_pins>,"brcm,pins:0",<&can2>,"interrupts:0";
};

};

on RPi
sudo apt-get install device-tree-compiler
dtc -@ -I dts -O dtb -o mcp2515-can2.dtbo mcp2515-can2-overlay.dts

Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /fragment@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /fragment@2 has a unit name, but no reg property

sudo cp mcp2515-can2.dtbo /boot/overlays

in /boot/config.txt
dtparam=spi=on
dtoverlay=mcp2515-can2-overlay,oscillator=16000000,interrupt=25
dtoverlay=spi-bcm2835-overlay

CAN2 was not created.

sudo /sbin/ip link set can2 up type can bitrate 500000

[karu2003]

need
dtoverlay=spi1-1cs

[ahmedawad1]

your .dts source file looks ok but I think you are missing in the config.txt :

Change dtoverlay=spi1-3cs to dtoverlay=spi1-3cs,cs0_spidev=off

Try it!

[karu2003]

I have only one SPI1.0
CE1 and CE2 use for RTS, CTS

[Wong-Jhon]

@karu2003
Maybe there is can0 not can2,
try ifconfig -a first ,and see what it is.
In my test, CAN0 was created when I connected mcp2515 to spi1 .

[karu2003]

Thanks, it works. CAN0 is better. :)

[DavidDavid123]

Hello , I'm trying to do the same - connect the Canbus to SPI1 - I think I did everything written here - but it doesn't work,
this is what I have in the config.txt:

dtparam=i2c_arm=on
dtparam=spi=on
dtoverlay=spi1-1cs
dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=12
dtoverlay=spi1-bcm2835-overlay
enable_uart=0
dtoverlay=pi3-disable-bt

the connection are:
int -- 32 (GPIO 12)
sck -- 40 (GPIO 21 , SPI1 SCLS)
si -- 38 (GPIO 20 , SPI1 MOSI)
so -- 35 (GPIO 19 , SPI1 MISO)
cs -- 12 (GPIO 18 , SPI1 CS0)
gnd -- 6 (GND)
vcc - 2 (5V)

but I can't see the can0

why?
what am I missing \ doing wrong?

Thanks,

[pelwell]

dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=12

Shouldn't that be:

dtoverlay=mcp2515-can1,oscillator=8000000,interrupt=12
                     ^

?