Overlays as with BeagleBone Black

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1

On the BeagleBone Black, I used the overlays defined in /boot/uEnv.txt to enable CAN and some UARTs and to disable several things like HDMI etc. Now I received my BBAI a few days ago where the whole overlay setup has been removed from uEnv.txt.

I then went ahead and tried to use the config-pin tool but for any pin I tried (I even tried to set some to GPIO) it errored out (I can’t look up the error right now but could tomorrow, if it matters).

My question: How do I enable peripherals like CAN and UART (with or without overlays, it doesn’t matter to me)?

I used the Debian 9.9 LXQT image (https://debian.beagleboard.org/images/am57xx-debian-9.9-lxqt-armhf-2019-08-03-4gb.img.xz)

2

I’m in the middle of trying this to get spidev/spi2 to work: https://www.elinux.org/EBC_Exercise_41_Pin_Muxing_for_the_AI

3

Thanks, that looks like it might work. I am a bit surprised though, that after the relative ease of use of config-pin and overlays, we should now be back at having to compile DTBs ourselves. I assume (hope) this is just temporary and in the future, there will be simpler solutions again.

4

Sadly, with the AM5, we can't do the pinmux from userspace.. (hardware
bugs)... Everything must be done early..

Regards,

5

Hallo Robert,

i need to activate the /dev/i2c-2 on the beaglebone AI. When i got that right i have to add a node in the device tree in order to activate it.

Can you tell me what i have to add there?

Kind Regards

6

i need to activate the /dev/i2c-2 on the beaglebone AI. When i got that right i have to add a node in the device tree in order to activate it.
Can you tell me what i have to add there?

Don’t know if this will help you, but to get access to the eeprom on my cape I added:

`
&i2c4 {
eeprom: eeprom@54 {
compatible = “atmel,24c32”;
reg = <0x54>;
};
};

`

to the .dts After that /sys/bus/i2c/devices/3-0054/eeprom appeared and I could do e.g. “hexdump -C …”.

Be sure to set the iopads accordingly. I used this:

`
DRA7XX_CORE_IOPAD(0x3440, PIN_INPUT_PULLUP | MUX_MODE7) // R6 P9.19a i2c4_scl
DRA7XX_CORE_IOPAD(0x357C, PULL_DIS | MUX_MODE15) // F4 P9.19b
DRA7XX_CORE_IOPAD(0x3444, PIN_INPUT_PULLUP | MUX_MODE7) // T9 P9.20a i2c4_sda
DRA7XX_CORE_IOPAD(0x3578, PULL_DIS | MUX_MODE15) // D2 P9.20b

`

/opt/scripts/device/bone/show-pins.pl shows:

P9.19a 16 R6 7 fast rx up i2c4_scl kiwisdr (cape_pins_kiwi)

P9.20a 17 T9 7 fast rx up i2c4_sda kiwisdr (cape_pins_kiwi)

P9.20b 94 D2 f fast Driver off kiwisdr (cape_pins_kiwi)

P9.19b 95 F4 f fast Driver off kiwisdr (cape_pins_kiwi)

7

To reply to myself: After looking at it again and reading through other people’s pages, I managed to get the CAN device working with this DTS (after cloning the BeagleBoard-DeviceTrees repo):

`

#include “am5729-beagleboneai.dts”

/ {
chosen {
base_dtb = “am5729-beagleboneai-kitepower.dts”;
base_dtb_timestamp = TIMESTAMP;
};
};

// The second name (pinmux_dcan2_pins) seems not used
&dra7_pmx_core {
dcan2_pins: pinmux_dcan2_pins {
pinctrl-single,pins = <
/* P9_24: uart1_txd.d_can2_rx /
DRA7XX_CORE_IOPAD(0x368C, PIN_INPUT_PULLUP | MUX_MODE2)
/ P9_26: uart1_rxd.d_can2_tx */
DRA7XX_CORE_IOPAD(0x3688, PIN_OUTPUT_PULLUP | MUX_MODE2)

;
};
};

// Initially defined in dra7 (which is included through multiple layers) as disabled
&dcan2 {
pinctrl-names = “default”; // Not sure what this is used for
pinctrl-0 = <&dcan2_pins>;
status = “okay”;
};

`

This muxes the 2 pins with the CAN peripheral to CAN.

After compiling this into a DTB, putting it on the beagle and setting it up in the uEnv.txt, I only need to bring up the CAN device:

sudo ip link set can0 up type can bitrate ${bitrate}

and CAN works (I use a bit rate of 125000).

Thanks for the people who took time to document their efforts and I hope this helps others.

8

Did you do any further changes on your BBAI to make this device tree run?

I just want to do a simple pinmux to give PRU1_0 some gpio’s, but everytime I edit my uEnv.txt, the kernel does not load after reboot. So I was looking around and found this thread.
I tried to copy your .dts, compiled it and copied it to /boot/dtbs/4.14xxxx. However, the kernel does not load. (Btw. I am using the 4.14.108-ti-xenomai-r127 kernel, didn’t test with normal ti kernel yet)

Another dts I tried is descriped here: https://www.element14.com/community/community/project14/visionthing/blog/2019/11/16/beagleboard-ai-brick-recovery-procedure#jive_content_id_BBAI_SETUP_CHECKLIST
Still no success.

The only other device tree that worked for me, is the am5729-beagleboneai-roboticscape.dtb
Any any ideas on this?

9

Did you do any further changes on your BBAI to make this device tree run?

Yes, this is the exact DTB I am using, everything else is stock (I
think I was using the Debian 9.10 IoT image).

I just want to do a simple pinmux to give PRU1_0 some gpio's, but everytime I edit my uEnv.txt, the kernel does not load after reboot. So I was looking around and found this thread.
I tried to copy your .dts, compiled it and copied it to /boot/dtbs/4.14xxxx. However, the kernel does not load. (Btw. I am using the 4.14.108-ti-xenomai-r127 kernel, didn't test with normal ti kernel yet)

I am using 4.19.x-ti, so this could certainly be an important difference.

Bert