4.8. Android Camera

The AM62Px supports 2 camera interfaces:

UVC (Usb Video Class) cameras, which are mainly known as webcams.
Camera over CSI-2

This page will mainly describe Camera over CSI-2.

Note

Right now, only one YUV sensor is supported: The Omnivision OV5640.

4.8.1. Hardware setup

The following hardware is required to use the CSI-2 camera:

ALINX ov5640 sensor module (AN5641)
21 pin raspberry pi CSI ribbon
AM62Px SK EVM board

Plug the CSI ribbon in J6 and on the camera module as following:

4.8.2. Software configuration

After flashing, make sure to halt in the U-Boot shell and run

=> env set dtbo_index 2
=> saveenv

This ensures that the k3-am625-sk-csi2-ov5640.dtbo device-tree overlay gets applied by the bootloader. With the applied overlay, the following drivers should probe:

ov5640, which is the sensor driver
cdns-csi2rx which is the receiver (CSI2RX) driver
j721e-csi2rx which is a TI-specific glue between cdns-csi2rx and the DMA engine (SHIM)

Once booted to the home screen, we can start a capture session using the default AOSP provided camera app:

$ adb shell 'am start -a android.media.action.IMAGE_CAPTURE'

4.8.3. Debugging tips

4.8.3.1. Using the `cam` commandline

cam is a commandline utility to do low level captures and save them to disk.

Some useful cam commands are:

$ adb wait-for-device root && adb wait-for-device

# get information about streams and formats
$ adb shell 'cam --camera 1 --info'

# take a 1920x1080 capture in yuyv
$ adb shell 'cam -c1 -C1 -s pixelformat=YUYV --file=/data/'

# pull it from the device and convert it to png using ffmpeg
$ adb pull '/data/frame-cam0-stream0-000000.bin'
$ ffmpeg -f rawvideo -s 1920x1080 -pix_fmt yuyv422 -i frame-cam0-stream0-000000.bin picture.png

Since the Android HAL has exclusive access to the camera, the camera app should not be running when we try to run a capture with cam.

4.8.3.2. Enabling additional kernel logs

v4l2 has its own logging system. To have additional logs in dmesg, do the following:

$ adb wait-for-device root && adb wait-for-device

$ adb shell 'echo 0x3f > /sys/class/video4linux/video0/dev_debug'
$ adb shell 'echo 1 > /sys/module/videobuf2_common/parameters/debug'

4.8.3.3. Android specific tricks

4.8.3.3.1. List cameras from Android system

To list if the camera is enumerated by the Android system, run:

$ adb shell 'dumpsys media.camera'

4.8.3.3.2. Logging

To filter logs from logcat, use:

$ adb logcat | grep -i -e libcamera -e 'F DEBUG';

To change the log level for libcamera, edit the HAL’s init.rc

diff --git a/camera/android.hardware.camera.provider@2.5-service_64_am62x.rc b/camera/android.hardware.camera.provider@2.5-service_64_am62x.rc
index 4808aea8dcee..f4637d7213a8 100644
--- a/camera/android.hardware.camera.provider@2.5-service_64_am62x.rc
+++ b/camera/android.hardware.camera.provider@2.5-service_64_am62x.rc
@@ -16,5 +16,5 @@ service vendor.camera-provider-2-5 /vendor/bin/hw/android.hardware.camera.provid
     capabilities SYS_NICE
     task_profiles CameraServiceCapacity MaxPerformance
     override
-    setenv LIBCAMERA_LOG_LEVELS *:INFO
+    setenv LIBCAMERA_LOG_LEVELS *:DEBUG
     setenv LIBCAMERA_LOG_FILE syslog

4.8.3.3.3. The Camera app disappears after booting Android

The Android Camera app runs on the first Android boot to detect whether a physical camera sensor is present and useable by the device. If it can’t find one, it will disable itself and thus disappear from the launcher.

To re-enable it, use package manager via adb:

$ adb root
$ adb shell pm enable com.android.camera2/com.android.camera.CameraLauncher