boards: frdm_mcxn947: turn OV7670 into a shield #89131

josuah · 2025-04-26T11:50:23Z

Dependencies:

drivers: video: Migrate ov7670 and smartdma to use video interfaces binding #88323

The FRDM-MCXN board is featuring an Arducam connector originally designed for the Arduino GIGA R1, and spread broadly since then for inexpensive OmniVision and low-power Himax image sensor modules.

Other modules than the Olimex OV7670 can be used.

This also proposes an arducam,dvp-20pin-connector GPIO nexus:
https://github.com/zephyrproject-rtos/zephyr/pull/89131/files#diff-a39283efe7f5b76e206c8d2b9b65c4b45d130ceb1aa6bb8a0083486793172537

josuah · 2025-04-26T12:00:35Z

Tested with UVC (by cherry-picking commits):

Before:

After:

It does not really look like correct data, but it is showing the same thing before and after, which shows the current PR does not break the sensor operation. :)

[EDIT: no problem with other hardware on UVC (i.e. Arducam Nicla or virtual source), I'll try with other sensors to debug this, which this PR helps doing]

josuah · 2025-04-26T12:49:39Z

dts/bindings/gpio/arducam,dvp-20pin-connector.yaml

+  - dvp_20pin_interface: the video interface that receives the video
+    feed and use with the zephyr,camera chosen node.
+
+  - dvp_20pin_ep_in: video endpoint of the devkit receiving the video
+    feed (see video-interfaces.yaml).
+
+  - dvp_20pin_ep_out: video endpoint of the camera module to interconnect
+    with this endpoint (see video-interfaces.yaml).
+
+  - dvp_20pin_i2c: the I2C device of the devkit on which the camera
+    module is instantiated.
+
+  - dvp_20pin_gpio: the gpio nexus using the arducam,dvp-20pin-connector
+    that defines the camera 'reset' pin, 'power-down' pin, etc.


Shields does not talk about a zephyr_... prefix:

zephyr/boards/weact/mini_stm32h743/mini_stm32h743.dts

Lines 243 to 253 in 02f85b2

zephyr_camera_i2c: &i2c1 {

pinctrl-0 = <&i2c1_scl_pb8 &i2c1_sda_pb9>;

pinctrl-names = "default";

};

zephyr_camera_dvp: &dcmi {

pinctrl-0 = <&dcmi_hsync_pa4 &dcmi_pixclk_pa6 &dcmi_vsync_pb7

&dcmi_d0_pc6 &dcmi_d1_pc7 &dcmi_d2_pe0 &dcmi_d3_pe1

&dcmi_d4_pe4 &dcmi_d5_pd3 &dcmi_d6_pe5 &dcmi_d7_pe6>;

pinctrl-names = "default";

};

So I went with dvp_20pin_<sensorname> and dvp_20pin_<feature>.

Let me know if zephyr_camera_<...> is better!

Add the 20-pin camera connector used by at least Arducam, Waveshare, Olimex, Arduino, NXP, ST, Adafruit that connects image sensor module boards and devkits. Signed-off-by: Josuah Demangeon <me@josuah.net>

ngphibang

Thanks for the added shield.
Did you test the video capture sample ? I think you need to update the frdm_mcxn947_cpu0.overlay in the sample as well because the camera is now moved out of the board.

ngphibang · 2025-04-26T21:12:43Z

boards/nxp/frdm_mcxn947/frdm_mcxn947.dtsi

 		port {
-			sdma_ep_in: endpoint {
-				remote-endpoint-label = "ov7670_ep_out";
+			dvp_20pin_ep_in: endpoint {
+				remote-endpoint-label = "dvp_20pin_ep_out";
 			};
 		};


This should not be here but in the overlay as it is out of the board. If there are multiple ports / endpoints, you can reserve a port for it as below (but it's not the case here):

https://github.com/zephyrproject-rtos/zephyr/blob/main/dts/arm/nxp/nxp_rt11xx.dtsi#L911-#L934

I removed the remote-endpoint-label = "dvp_20pin_ep_out"; and it still works!
Is that what I should remove?

I am not sure how to remove the label itself dvp_20pin_ep_in: as the shield cannot know where it should insert itself on every board, the board.dts has to provide a label for the shield insertion point?

Thank you for your help as I learn DTS further.

josuah · 2025-04-27T00:09:46Z

Did you test the video capture sample ? I think you need to update the frdm_mcxn947_cpu0.overlay in the sample as well

Good point! Now I can remove it as the shield would select the zephyr,camera = &dvp_20pin_interface;.

Trying again after enabling the debug logging:

...
[00:00:05.271,000] <dbg> main: main: Got frame 307! size: 19200; timestamp 5271 ms
[00:00:05.286,000] <dbg> main: main: Got frame 308! size: 19200; timestamp 5286 ms
[00:00:05.302,000] <dbg> main: main: Got frame 309! size: 19200; timestamp 5302 ms
[00:00:05.318,000] <dbg> main: main: Got frame 310! size: 19200; timestamp 5318 ms
[00:00:05.334,000] <dbg> main: main: Got frame 311! size: 19200; timestamp 5334 ms
[00:00:05.357,000] <dbg> main: main: Got frame 312! size: 19200; timestamp 5357 ms
[00:00:05.373,000] <dbg> main: main: Got frame 313! size: 19200; timestamp 5373 ms
[00:00:05.388,000] <dbg> main: main: Got frame 314! size: 19200; timestamp 5388 ms
[00:00:05.404,000] <dbg> main: main: Got frame 315! size: 19200; timestamp 5404 ms
[00:00:05.420,000] <dbg> main: main: Got frame 316! size: 19200; timestamp 5420 ms
...

josuah · 2025-04-27T00:24:53Z

I was hitting a CI error when removing remote-endpoin-label so went with the workaround of setting it to = "empty";:

devicetree error: 'remote-endpoint-label' is marked as required in 'properties:' in /__w/zephyr/zephyr/dts/bindings/video/nxp,video-smartdma.yaml, but does not appear in <Node /soc/peripheral@50000000/smartdma@33000/video-sdma/port/endpoint in '/__w/zephyr/zephyr/misc/empty_file.c'>

ngphibang

I am not sure if this 20-pin shield is generic and not specific only to NXP boards. If it is generic (as currently implemented), it will be similar to the dvp_fpc24_mt9m114 shield used on the mimxrt1064_evk. Could you take a look at
https://github.com/zephyrproject-rtos/zephyr/blob/main/dts/arm/nxp/nxp_rt10xx.dtsi#L885-#L890
https://github.com/zephyrproject-rtos/zephyr/blob/main/boards/nxp/mimxrt1064_evk/mimxrt1064_evk.dts#L352-#L354
https://github.com/zephyrproject-rtos/zephyr/blob/main/boards/shields/dvp_fpc24_mt9m114/dvp_fpc24_mt9m114.overlay
Could you add an entry for the frdm_mcxn947_cpu0 in the video capture sample README, section "Build and Running" as well ?
https://github.com/zephyrproject-rtos/zephyr/blob/main/samples/drivers/video/capture/README.rst

Thanks

ngphibang · 2025-04-27T07:48:06Z

boards/nxp/frdm_mcxn947/frdm_mcxn947.dtsi

 &smartdma {
-	status = "okay";
 	program-mem = <0x4000000>;
-	video_sdma: video-sdma {
-		status = "okay";
+	/* Shields do not enable video-sdma parent node */
+	status = "okay";
+
+	dvp_20pin_interface: video_sdma: video-sdma {
 		compatible = "nxp,video-smartdma";
 		pinctrl-0 = <&pinmux_smartdma_camera>;
 		pinctrl-names = "default";
 		vsync-pin = <4>;
 		hsync-pin = <11>;
 		pclk-pin = <5>;
+		status = "disabled";

 		port {
-			sdma_ep_in: endpoint {
-				remote-endpoint-label = "ov7670_ep_out";
+			dvp_20pin_ep_in: endpoint {
+				remote-endpoint-label = "empty";
 			};
 		};
 	};


Sorry, I am confused here. I think the right way is keeping the video sdma node and label it as a dvp_20pin_interface as in https://github.com/zephyrproject-rtos/zephyr/blob/main/boards/nxp/mimxrt1064_evk/mimxrt1064_evk.dts#L352-#L354

ngphibang · 2025-04-27T07:48:52Z

boards/shields/dvp_20pin_ov7670/dvp_20pin_ov7670.overlay

+&dvp_20pin_ep_in {
+	remote-endpoint-label = "dvp_20pin_ep_out";
+};
+
+&dvp_20pin_interface {
+	status = "okay";
+};


The endpoint should be inside the interface node.

The OV7670 was defined as part of the FRDM-MCXN947 board attached to the SmartDMA and I2C peripheral. Migrate the devicetree to a reusable shield that can be swapped with other image sensors. Signed-off-by: Josuah Demangeon <me@josuah.net>

Add FRDM-MCXN947 to the video capture sample documentation and twister YAML configuration, using the DVP OV7670 camera module newly introduced. Signed-off-by: Josuah Demangeon <me@josuah.net>

josuah · 2025-04-27T11:16:12Z

Force-push:

Added a README entry for the video capture sample, preview soon available here or in the meantime here.
Modified the devicetree to use the same declaration style as mimxrt1064_evk

not sure if this 20-pin shield is generic and not specific only to NXP boards

It is the closest thing from a standard for DVP we might have, plenty of Arducam modules available via UCTRONICS, and some 3rd-party too, like the Olimex one for the OV7670. But a de-facto standard, no official document describing it.

This will help for testing all these drivers!

josuah marked this pull request as draft April 26, 2025 11:50

josuah added area: Drivers platform: NXP NXP area: Video Video subsystem area: camera labels Apr 26, 2025

github-actions bot added area: GPIO area: Shields Shields (add-on boards) area: Samples Samples platform: NXP Drivers NXP Semiconductors, drivers labels Apr 26, 2025

github-actions bot requested review from avisconti, dbaluta, decsny, DerekSnell, dleach02, erwango, henrikbrixandersen, jfischer-no, kartben, loicpoulain, manuargue, mmahadevan108, mnkp, ngphibang and Raymond0225 April 26, 2025 11:51

github-actions bot assigned kartben Apr 26, 2025

josuah added the In progress For PRs: is work in progress and should not be merged yet. For issues: Is being worked on label Apr 26, 2025

josuah force-pushed the pr-frdm-mcxn947-shield branch from a0d81be to e03e9da Compare April 26, 2025 12:29

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josuah force-pushed the pr-frdm-mcxn947-shield branch from e03e9da to 283745b Compare April 26, 2025 13:24

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josuah removed the In progress For PRs: is work in progress and should not be merged yet. For issues: Is being worked on label Apr 26, 2025

dts: bindings: gpio: add arducam 20-pin camera connector

67f7dd1

Add the 20-pin camera connector used by at least Arducam, Waveshare, Olimex, Arduino, NXP, ST, Adafruit that connects image sensor module boards and devkits. Signed-off-by: Josuah Demangeon <me@josuah.net>

josuah force-pushed the pr-frdm-mcxn947-shield branch from d171799 to c159802 Compare April 26, 2025 15:27

josuah marked this pull request as ready for review April 26, 2025 15:27

github-actions bot added the area: Devicetree label Apr 26, 2025

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usb: device_next: new USB Video Class (UVC) implementation #76798

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josuah added 2 commits April 27, 2025 11:11

samples: drivers: video: capture: add FRDM-MCXN947

cb237fc

Add FRDM-MCXN947 to the video capture sample documentation and twister YAML configuration, using the DVP OV7670 camera module newly introduced. Signed-off-by: Josuah Demangeon <me@josuah.net>

josuah force-pushed the pr-frdm-mcxn947-shield branch from 13ea982 to cb237fc Compare April 27, 2025 11:11

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boards: frdm_mcxn947: turn OV7670 into a shield #89131

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	zephyr_camera_i2c: &i2c1 {
	pinctrl-0 = <&i2c1_scl_pb8 &i2c1_sda_pb9>;
	pinctrl-names = "default";
	};

	zephyr_camera_dvp: &dcmi {
	pinctrl-0 = <&dcmi_hsync_pa4 &dcmi_pixclk_pa6 &dcmi_vsync_pb7
	&dcmi_d0_pc6 &dcmi_d1_pc7 &dcmi_d2_pe0 &dcmi_d3_pe1
	&dcmi_d4_pe4 &dcmi_d5_pd3 &dcmi_d6_pe5 &dcmi_d7_pe6>;
	pinctrl-names = "default";
	};

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