Tiny Core Linux

Tiny Core Base => TCB Q&A Forum => Topic started by: Brycey92 on April 12, 2018, 01:44:27 AM

Title: Tiny Core/Pi Zero refuses to use SPI0 for CAN
Post by: Brycey92 on April 12, 2018, 01:44:27 AM

Hello, all! This is my first post on this board, so please excuse any poor formatting or rookie mistakes.
Anyway, I recently started a project using Tiny Core on a Pi Zero to try to interface with my car's CAN bus.

I've attempted to get this MCP2515+TJA1050 board (https://www.amazon.com/gp/product/B01HXI5LH8/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1) to work by altering the PCB and connecting it to the Pi as discussed here (https://www.raspberrypi.org/forums/viewtopic.php?t=141052).

I've set mounted home and tce directories in my cmdline.txt, since this Pi will not be able to connect to the internet to download extensions in its normal operation, and it will need to read many audio files which I would prefer were not copied to RAM on every boot.

Additionally, I have put these 2 lines at the bottom of my config.txt:

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dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=12
dtoverlay=spi-bcm2835-overlayand I changed

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dtparam=i2c=on,spi=on,i2s=on to

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dtparam=i2c=off,spi=on,i2s=off elsewhere in the file to slightly speed up boot times.

To get the can0 interface recognized on spi0.0, I placed the following files from the source archive into /usr/local inside two .tcz extensions which I have load on boot:

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/lib/modules/4.9.22-piCore/kernel/drivers/net/can/can-dev.ko
/lib/modules/4.9.22-piCore/kernel/drivers/net/can/spi/mcp251x.ko


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/lib/modules/4.9.22-piCore/kernel/net/can/can-raw.ko
/lib/modules/4.9.22-piCore/kernel/net/can/can-gw.ko
/lib/modules/4.9.22-piCore/kernel/net/can/can-bcm.ko
/lib/modules/4.9.22-piCore/kernel/net/can/can.ko
I attempted to use code in a C++ program to listen for messages over can0 using the socketcan broadcast manager, but when that didn't work, I compiled can-utils and ran the following 2 commands:

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tce-load -il iproute2
sudo ip link set can0 up type can bitrate 500000I set up another of these MCP2515 boards with an Arduino Uno to create a testbench CAN bus. I then connected the 2 modules together and placed jumpers on the boards to enable the 120 ohm resistors between CAN high and low on each end of the bus, and put a sketch on the Arduino to send a CAN message every second. When I ran candump on the Pi and scoped each pin of the MCP boards, I discovered that there was normal activity on the Arduino's SPI connection to the MCP board, and the signal was present on both sides of the CAN bus at the boards, but on the Pi's SPI connection, only INT, CS, and VCC were high at 3.3v, while SCK, SI, SO, and of course GND were at 0v. At no point during sending or receiving with my program nor with candump, cangen, and cansend did any of these pins change.

At this point, I'm at a loss as to what to do next to diagnose this or get it working, so any help is appreciated! Thanks for reading!

Title: Re: Tiny Core/Pi Zero refuses to use SPI0 for CAN
Post by: bmarkus on April 12, 2018, 04:15:01 AM

Check config.txt and enable SPI DT overlay if necessary.

Title: Re: Tiny Core/Pi Zero refuses to use SPI0 for CAN
Post by: patrikg on April 12, 2018, 06:49:59 AM

And you can maybe get something from another thread regarding CAN BUS.

http://forum.tinycorelinux.net/index.php/topic,18858.0.html

Title: Re: Tiny Core/Pi Zero refuses to use SPI0 for CAN
Post by: Brycey92 on April 12, 2018, 12:55:04 PM

Quote from: bmarkus on April 12, 2018, 04:15:01 AM

Check config.txt and enable SPI DT overlay if necessary.

Which SPI DT overlay should I enable, aside from the 2 overlays I already have enabled?

Quote from: patrikg on April 12, 2018, 06:49:59 AM

And you can maybe get something from another thread regarding CAN BUS.

http://forum.tinycorelinux.net/index.php/topic,18858.0.html

Thanks for the link, but I actually used that thread to get as far as I am. As there is no Tiny Core 9.x Arm 6 extension in the official repo, I don't know if the files listed in that thread and the others I found are all that would need to go into a CAN extension.

Title: Re: Tiny Core/Pi Zero refuses to use SPI0 for CAN
Post by: Brycey92 on April 14, 2018, 12:41:06 AM

By the way, the following is the output of lsmod:

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Module                  Size  Used by    Not tainted
can_bcm                14631  1
can                    30005  1 can_bcm
i2c_dev                 6802  0
snd_usb_audio         144481  1
snd_usbmidi_lib        22479  1 snd_usb_audio
snd_rawmidi            23989  1 snd_usbmidi_lib
snd_seq_device          5234  1 snd_rawmidi
snd_hwdep               6479  1 snd_usb_audio
snd_bcm2835            23079  0
snd_pcm                96791  3 snd_usb_audio,snd_bcm2835
mcp251x                10503  0
can_dev                13841  1 mcp251x
snd_timer              22721  1 snd_pcm
snd                    69129  9 snd_usb_audio,snd_usbmidi_lib,snd_rawmidi,snd_seq_device,snd_hwdep,snd_bcm2835,snd_pcm,snd_timer
squashfs               33444 25
evdev                  11764  0
rfkill                 21444  0
bcm2835_gpiomem         3751  0
spi_bcm2835             7468  0
fixed                   3029  0
uio_pdrv_genirq         3718  0
uio                    10281  1 uio_pdrv_genirq
zram                   20761  1
zsmalloc               17097  1 zram