Cannot get SPI to work

jwjw · July 16, 2021, 3:30pm

Hi,
I am trying to enable SPI on my Nano devkit but I’m running into some problems. I’ve tried many things to get it to work but I always run into the same problem: There is no output on any of the CS, SCK, MOSI lines for both SPI devices (checked with a scope). I have tried spidev_test and my own program to write out data (verified to work on other devices).

The most straight-forward test I’ve done was on a clean install (downloaded sd-card image), and enabled SPI using jetsion-io. The devices do correctly show up as /dev/spidev*. Furthermore sudo /opt/nvidia/jetson-io/config-by-function.py -l enabled yields:

The following functions are enabled on the 40-pin header:
 1. spi1
 2. spi2

So it seems to me that jetson-io at least thinks SPI is properly enabled.

The file /boot/extlinux/extlinux.conf correctly defaults to the JetsionIO configuration (with custom device tree /boot/kernel_tegra210-p3448-0000-p3449-0000-b00-user-custom.dtb).
To double check the correct device tree gets loaded on boot, I extracted it using sudo dtc -I fs -O dts -o extracted.dts /proc/device-tree. The file is attached: extracted.dts (334.1 KB)

These entries look correct to me:

header-40pin-pinmux {
			phandle = <0x136>;
			linux,phandle = <0x136>;

			pin10 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "uart2_rx_pg1";
				nvidia,tristate = <0x1>;
				nvidia,function = "uartb";
				nvidia,pull = <0x2>;
			};

			pin19 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi1_mosi_pc0";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi1";
				nvidia,pull = <0x1>;
			};

			pin37 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi2_mosi_pb4";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi2";
				nvidia,pull = <0x1>;
			};

			pin27 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "gen1_i2c_sda_pj0";
				nvidia,tristate = <0x0>;
				nvidia,io-high-voltage = <0x1>;
				nvidia,function = "i2c1";
				nvidia,pull = <0x0>;
			};

			pin35 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "dap4_fs_pj4";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd3";
				nvidia,pull = <0x1>;
			};

			pin23 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi1_sck_pc2";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi1";
				nvidia,pull = <0x1>;
			};

			pin13 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi2_sck_pb6";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi2";
				nvidia,pull = <0x1>;
			};

			pin21 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi1_miso_pc1";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi1";
				nvidia,pull = <0x1>;
			};

			pin11 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "uart2_rts_pg2";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd2";
				nvidia,pull = <0x0>;
			};

			pin7 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "aud_mclk_pbb0";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd3";
				nvidia,pull = <0x0>;
			};

			pin38 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "dap4_din_pj5";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd3";
				nvidia,pull = <0x1>;
			};

			pin28 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "gen1_i2c_scl_pj1";
				nvidia,tristate = <0x0>;
				nvidia,io-high-voltage = <0x1>;
				nvidia,function = "i2c1";
				nvidia,pull = <0x0>;
			};

			pin18 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi2_cs0_pb7";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi2";
				nvidia,pull = <0x2>;
			};

			pin5 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "gen2_i2c_scl_pj2";
				nvidia,tristate = <0x0>;
				nvidia,io-high-voltage = <0x1>;
				nvidia,function = "i2c2";
				nvidia,pull = <0x0>;
			};

			pin36 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "uart2_cts_pg3";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd2";
				nvidia,pull = <0x2>;
			};

			pin26 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi1_cs1_pc4";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi1";
				nvidia,pull = <0x2>;
			};

			pin16 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi2_cs1_pdd0";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi2";
				nvidia,pull = <0x2>;
			};

			pin3 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "gen2_i2c_sda_pj3";
				nvidia,tristate = <0x0>;
				nvidia,io-high-voltage = <0x1>;
				nvidia,function = "i2c2";
				nvidia,pull = <0x0>;
			};

			pin24 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi1_cs0_pc3";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi1";
				nvidia,pull = <0x2>;
			};

			pin22 {
				nvidia,enable-input = <0x1>;
				nvidia,pins = "spi2_miso_pb5";
				nvidia,tristate = <0x0>;
				nvidia,function = "spi2";
				nvidia,pull = <0x1>;
			};

			pin12 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "dap4_sclk_pj7";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd3";
				nvidia,pull = <0x1>;
			};

			pin40 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "dap4_dout_pj6";
				nvidia,tristate = <0x1>;
				nvidia,function = "rsvd3";
				nvidia,pull = <0x1>;
			};

			pin8 {
				nvidia,enable-input = <0x0>;
				nvidia,pins = "uart2_tx_pg0";
				nvidia,tristate = <0x0>;
				nvidia,function = "uartb";
				nvidia,pull = <0x0>;
			};
		};

What does not look correct is the output of sudo cat /sys/kernel/debug/tegra_gpio:

Name:Bank:Port CNF OE OUT IN INT_STA INT_ENB INT_LVL
 A: 0:0 64 40 40 24 00 00 000000
 B: 0:1 f0 00 00 00 00 00 000000
 C: 0:2 1f 00 00 00 00 00 000000
 D: 0:3 00 00 00 00 00 00 000000
 E: 1:0 40 00 00 40 00 00 000000
 F: 1:1 00 00 00 00 00 00 000000
 G: 1:2 0c 00 00 00 00 00 000000
 H: 1:3 fd 99 00 60 00 00 000000
 I: 2:0 07 07 03 02 00 00 000000
 J: 2:1 f0 00 00 00 00 00 000000
 K: 2:2 00 00 00 00 00 00 000000
 L: 2:3 00 00 00 00 00 00 000000
 M: 3:0 00 00 00 00 00 00 000000
 N: 3:1 00 00 00 00 00 00 000000
 O: 3:2 00 00 00 00 00 00 000000
 P: 3:3 00 00 00 00 00 00 000000
 Q: 4:0 00 00 00 00 00 00 000000
 R: 4:1 00 00 00 00 00 00 000000
 S: 4:2 a0 80 00 00 00 00 000000
 T: 4:3 01 01 00 00 00 00 000000
 U: 5:0 00 00 00 00 00 00 000000
 V: 5:1 03 00 00 02 00 00 000000
 W: 5:2 00 00 00 00 00 00 000000
 X: 5:3 78 08 08 70 00 60 606000
 Y: 6:0 06 00 00 02 00 00 000000
 Z: 6:1 0f 08 08 04 00 06 020600
AA: 6:2 00 00 00 00 00 00 000000
BB: 6:3 01 00 00 00 00 00 000000
CC: 7:0 92 80 80 00 00 12 121200
DD: 7:1 01 00 00 00 00 00 000000
EE: 7:2 00 00 00 00 00 00 000000
FF: 7:3 00 00 00 00 00 00 000000

If I interpret it correctly, the SPI pins at C00-C04 are set up as GPIO (CNF = 0x1f = 00011111) and not SFIO (0x00). I don’t understand why though, since the dtb seems correct?

ShaneCCC · July 19, 2021, 6:27am

What’s the version?
I check without problem on r32.5.1

jwjw · July 19, 2021, 7:29am

R32.5.1 as well.
I should add that I also found out over the weekend that after I manually set the CNF register to SFIO (sudo busybox devmem 0x6000d008 8 0x00) SPI works normally. Of course, after each reboot the value gets reset to 0x1F.

ShaneCCC · July 19, 2021, 7:46am

Does your nano is emmc image instead of sdcard image version?

jwjw · July 19, 2021, 8:07am

Is there a way to verify which image is installed on the nano?

I didn’t use the flash utility, but downloaded the image from the nvidia site and burned it to an sd-card. I assumed this image is only available for the SD-version.
I got the image from here: Jetson Download Center | NVIDIA Developer , specifically I downloaded this image: https://developer.nvidia.com/jetson-nano-sd-card-image .

The .img-file contained in the archive has the following MD5 hash:

 md5 sd-blob-b01.img
MD5 (sd-blob-b01.img) = 82ce71bbaf5ff1104d007568a9dbc383

Edit: maybe this is relevant:

cat /etc/nv_boot_control.conf 
TNSPEC 3448-300---1-0-jetson-nano-qspi-sd-mmcblk0p1
COMPATIBLE_SPEC 3448-300---1--jetson-nano-devkit-mmcblk0p1
TEGRA_CHIPID 0x21
TEGRA_OTA_BOOT_DEVICE /dev/mtdblock0
TEGRA_OTA_GPT_DEVICE /dev/mtdblock0

ShaneCCC · July 19, 2021, 8:42am

What’s the cat /etc/nv_tegra_release?
Could you install the system image by sdkmanager to check if any different?

jwjw · July 19, 2021, 8:56am

# R32 (release), REVISION: 5.1, GCID: 27362550, BOARD: t210ref, EABI: aarch64, DATE: Wed May 19 18:07:59 UTC 2021

Installing through sdk manager is a bit tricky right now, I am running Ubuntu 20 on my desktop which I think doesn’t play nice with the SDK manager:

ShaneCCC · July 19, 2021, 9:25am

It’s could be the bootloader didn’t update cause the pin been configure as GPIO. That’s why would like to check if using sdkmanager to install it.

jwjw · July 19, 2021, 9:27am

ok I will find a way

jwjw · July 19, 2021, 1:29pm

Using SDK manager fixed it, thanks!
Something that was not stored on the SD-card was configured wrong then? In the past I have messed around with pinmuxes etc., I guess this could be the cause.
What other (persistent) storage is there outside of the SD-card?

ShaneCCC · July 20, 2021, 2:13am

As I mention in early comment it could be bootloader didn’t update if you only update the sd-card image only.

system · September 27, 2021, 1:06pm

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Cannot get SPI to work

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