Camera

The AM62x supports 2 camera interfaces:

  1. UVC (Usb Video Class) cameras, which are mainly known as webcams.

  2. 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.

Hardware setup

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

  • ALINX ov5640 sensor module (AN5641)

    alinx_ov5640

  • 15 pin FPC ribbon

    15_pin_fpc_ribbon.jpg

  • AM62x SK EVM board

    am62x_sk_evm_front.jpg am62x_sk_evm_back.jpg

Plug the 15 pin FPC ribbon in J19 and on the camera module as following:

Software configuration

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

=> env set adtbo_idx 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'

Debugging tips

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.

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'

Android specific tricks

List cameras from Android system

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

$ adb shell 'dumpsys media.camera'

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

Incremental rebuilding

To quickly rebuild all libcamera components and restart the HAL, run:

$ export OUT_DIR=<your_out_dir>
$ source build/envsetup.sh && lunch am62x-ap4a-userdebug && \
    m libcamera camera.libcamera cam libyuv_chromium libcameraservice

# libcamera
$ cd $OUT_DIR/target/product/am62x/ && adb root && adb remount && \
    adb push vendor/lib/libcamera.so /vendor/lib && adb push vendor/lib64/libcamera.so /vendor/lib64

# camera.libcamera
$ adb push vendor/lib/hw/camera.libcamera.so /vendor/lib/hw && \
    adb push vendor/lib64/hw/camera.libcamera.so /vendor/lib64/hw

# cam
$ adb push vendor/bin/cam /vendor/bin/cam

# libyuv_chromium
$ adb push system/lib/libyuv_chromium.so /system/lib/ && \
    adb push system/lib64/libyuv_chromium.so /system/lib64/

# libcameraservice
$ adb push system/lib64/libcameraservice.so /system/lib64

# stop all possible camera related things
$ adb shell am force-stop com.android.camera2 && adb shell stop vendor.camera-provider-2-5 && adb shell stop cameraserver

# restart hal and camera server
$ adb shell start cameraserver && adb shell start vendor.camera-provider-2-5

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