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@ Copyright 2021 PHYTEC Messtechnik GmbH, D-55129 Mainz.

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Introduction

The SBC kits (Single-Board-Computer) from PHYTEC represent an ideal basis for testing and the first design steps with phyCAM camera modules. The kit forms the starting point for your development project. The kit can be used to develop and test application software before your own adapted hardware is available. It is also an optimal platform for testing special hardware extensions before you create a complex application board.

This optional step secures your design and at the same time provides software development with an opportunity to adapt newly added hardware components. Extensions can be easily connected via the extension interfaces of the baseboards included in the kit. In the simplest case, a freely wired hole grid structure is sufficient.

For certain combinations of controller modules, camera modules, and lenses, we offer ready-made kits. If the combination you require is not available, we recommend that you first put a similarly-equipped kit into operation and then connect the camera you require to the kit.

We will be happy to advise you on the best way to carry out your project.

SBC Kit Start-Up

Before you try out the camera and image processing functions, we recommend that you first familiarize yourself with the basic functions of the kit and the associated development environment. Each kit contains a Quick Start Guide that guides you through installing the software on your development PC and configuring the hardware.

Connecting and Starting the Camera

Before You Start

The following components are required for the camera setup:

• PHYTEC SBC-Kit with power supply and serial connection (RS232 or USB)
• Camera module, with camera cable, lens holder, and lens

If you have ordered the corresponding kit as an Embedded Imaging Kit, all hardware components required for installation are already included.

As a rule, both the extension of an existing kit by one camera and the extension of an existing video kit by additional cameras is possible without problems with an existing phyCAM interface.

Before connecting and starting up the camera, carry out the first steps of the "Quick Start Instructions" of the respective kit. To start the scripts on the module, follow the steps to establish a serial connection with the module. You can use the terminal program suggested in the manual or your own terminal program.

To transfer saved image files to a PC (host) via Ethernet, follow the steps to establish an FTP connection. You can use the FTP server suggested in the manual or your own FTP server.

Connecting the Camera

Connecting a phyCAM-P Camera

Disconnect the system before connecting the camera.

Open the latch of the 33-pin FFC connector on the camera. Check which type of connector you have. The camera module can be equipped with a shift-lock type or a flip-lock type.

Shift-Lock connector:

• Pull the socket clip in the direction of the cable entry and lift it slightly.

phyCAM-P Shift Lock – FFC Socket Camera Connection

• Plug the 33-pin FFC cable into the FFC socket with the contact surfaces facing downwards until you feel the stop. The reinforcement of the FFC cable (usually highlighted in color) points to the bracket of the socket.
• Lock the FFC socket by pressing the clip down again and pushing it in until it stops.

Flip-lock connectors:

• Lift the lock upwards.

phyCAM-P Flip Lock – FCC Socket Camera Connection

• Plug the 33-pin FFC cable into the FFC socket with the contact surfaces facing downwards until you feel the stop. The reinforcement of the FFC cable (usually highlighted in color) points to the bracket of the socket.
• Lock the FFC socket by carefully pressing down on the bracket.

A type-A FFC cable (stripped and reinforced on the same side) is supplied with the kit. This ensures the correct signal assignment between the camera and the baseboard in the kit.

The position of the camera socket on the baseboard can be found in the hardware manual of the kit. Parallel to the connector designation (e.g. X100), some basic boards also have "CAM" printed on the board. The phyCAM-P interface is a 33-pin FFC socket, which can be installed standing or lying on the board.

The FFC cable is plugged in exactly the same way as the cable is plugged into the camera FFC socket.

phyCAM-P FFC Socket Camera Connection 

Connecting a phyCAM-S Camera

Disconnect the system before connecting the camera.

To connect the camera to a phyCAM-S system, a camera cable with an 8-pin Hirose connector is required (e.g. PHYTEC WK262 0.2). The Hirose plug is plugged into the matching counterpart on the camera module and the SBC. For orientation, there are two guide lugs on the upper side. These must snap into the corresponding recesses of the camera socket when plugged in.

phyCAM-S/S+ Hirose Camera Connection

The position of the camera jack on the SBC can be found in the kit's Quick Start manual. Parallel to the connector designation (e.g. X100), some basic boards also have the imprint "CAM" on the board. The phyCAM-S/S+ interface is a Hirose socket similar to the camera module, but more rarely an RJ-45 socket.

The RJ-45 connector of the camera cable is plugged into the RJ-45 camera jack on the motherboard.

phyCAM-S RJ-45 Camera Connection

The bracket on the plug serves both as reverse polarity protection and as a locking device. Push the RJ-45 plug into the socket until it audibly clicks into place.

Open the lock of the 30-pin FFC connector on the camera by lifting the lock upwards.

phyCAM-M Flip Lock – FCC Socket Camera Connection

• Plug the 33-pin FFC cable into the FFC socket with the contact surfaces facing downwards until you feel the stop. The reinforcement of the FFC cable (usually highlighted in color) points to the bracket of the socket.
• Lock the FFC socket by carefully pressing down on the bracket.

A type-A FFC cable (stripped and reinforced on the same side) is supplied with the kit. This ensures the correct signal assignment between the camera and the baseboard in the kit.

The position of the camera socket on the baseboard can be found in the hardware manual of the kit. Parallel to the connector designation (e.g. X100), some basic boards also have "CAM" printed on the board. The phyCAM-P interface is a 33-pin FFC socket, which can be installed standing or lying on the board.

The FFC cable is plugged in exactly the same way as the cable is plugged into the camera FFC socket.

Demo Application

Bootloader Configuration

Before using the supplied examples, you should make sure that the camera module you are using is correctly configured in the bootloader environment.

Since BSP version PD16.0.1, the configuration for a camera module is done with the program "of_camera_selection", which is called up during the boot process in a script. The procedure is described in the corresponding Quickstart or "phyCAM - Getting Started" documentation of the Linux software.

General Procedure

1. Interrupt the boot processReset your SBC to restart the controller module.
   During the output of:

   Hit m for menu or any other key to stop autoboot:

   press ENTER to stop at the bootloader prompt.
   
   

2. Configure the Bootloader Environment
   Enter the following call in your terminal program:

   edit env/config-expansions

   Scroll down to the following line or lines using the 'Scroll down' button:

   of_camera_selection -a 0x48 -p 0 -b phyCAM-P VM-010-BW

   Program parameters:
   -p: Port number of the camera interface [0/1]
   -b: Bus type of the camera interface [phyCAM-P/phyCAM-S+]
   -a: I²C address of the camera module [usually 0x48 at -p 0 / 0x5d at -p 1] see hardware manual of the respective camera module for more information
   Camera module designations VM-0xx-BW / VM-0xx-COL (VM-009 for VM-009 and VM-050 for VM-050/051)
   Press 'Ctrl+D' to temporarily save your changes and quit the editor.

3. Save your changes:

   saveenv

4. Reboot the Kernel:
   Call:

   boot

   to boot the kernel from the default boot source.

Start Live-Image

Start the system and follow the boot process on the terminal of your serial connection.

Start-up Boot Screen

Log in to the system and use the >ls< command to list the existing files and subdirectories in your home directory.

Login and Home Directory File /Folder List

Change to the subdirectory with the GStreamer examples (cd xxx with "xxx" = name of the directory). List the contents of the directory again with >ls<.

GStreamer File/Folder List

The executable example scripts start with "bwcam" or "colcam". The file "func.sh" is a shell script in which general settings for the demo scripts are made. Files with the extension .txt contain extended register settings for the GStreamer plugin "i2c file". Details can be found in the document "LAN-052e_AppNote_Set_Cam_Register").

The demo scripts are structured as follows:

• Integration of the shell script (e.g.: `dirname $0`/func.sh)
• Use functions from the shell script (e.g. init_dev) to parameterize the GStreamer call.
• Configuring the camera with "v4l2-ctl
• Configuring the Videopipline with "media-ctrl".
• start the GStreamer (e.g.: gst-launch \)
• start various functions of the GStreamer (e.g.: v4l2src ! \)

To start a script, enter the desired file on the console, for example:

./colcam-fbdev_640x480.sh

Information about the free multimedia framework GStreamer and its functions can be found at www.gstreamer.net. General handling of the GStreamer is described in the respective BSP-Phytec-Quickstart.

Here is a selection of some demo scripts:

Example Script Information

Scripts created specifically for a camera/camera sensor are located in separate subdirectories identified by the camera sensor name or description. Note that some scripts also depend on the hardware platform, meaning they are only for phyCARD or only for phyCORE platform.

Troubleshooting

In this section, we provide tips for step-by-step troubleshooting if an initial operation is not immediately successful.

Display Test

On the console, type the following command:

fbtest

Various geometric shapes and color patterns appear on the display.

Possible error:     No image is shown on the display:

Remedy:

• Check the connection to the display/monitor.
• Check the backlight connection.

Camera Live Image Test

Call up a file via the console, with a color variant matching your camera (monochrome/color) and the resolution matching your display.

Example:

./colcam-fbdev_640x480.sh

Example Script for the Camera Live Image Test

Depending on the BSP version, the script file automatically tries to load the correct driver or checks whether the preset driver could be loaded. If a corresponding camera is found, a message is displayed:
     camera 0-0: Detected an MT9V022 chip ID 1313, color sensor
and the live image is displayed on the screen.

Possible Error: No camera is detected.

No Camera Error

Remedy:

• Check the connection to the camera.
• Linux: check if the camera is supported by the kernel.
• Linux: check the timeliness of GStreamer examples

Possible Error: live image is displayed; delayed and with a slow frame rate

Remedy:
Due to several factors, a live image display with the highest frame rate is not always possible. The following factors can play a role here:

• Image data quantities (e.g.: image resolution, color format, etc.).
• Intermediate algorithms can require a lot of computing power.
• Conversion of color formats (e.g. Bayer Pattern to RGB) requires computing power.
• Different computing power and multimedia support of the controllers. It is possible that not all multimedia accelerators are supported by the demo application.
• Linux: As a modular framework, GStreamer is not speed-optimized.

In this case, the amount of image data and the algorithms used should be adapted to the task.

Changing Camera Modules Register Settings

The camera sensors offer various possibilities to influence image acquisition.

The corresponding settings are made in the camera registers. These registers can be read and written via the I²C interface. Many settings are already set automatically by the camera driver according to the driver calls.

Some of the more specific settings cannot be changed using the driver functions. The application programmer can access the camera registers directly and adjust the values accordingly.

Embedded Linux

PHYTEC's digital camera modules are supported by the appropriate camera drivers found in the PHYTEC Linux-BSP of the embedded controller module. The list of supported camera modules is constantly being broadened. The camera modules included in the respective distribution (kernel version) can be queried in the Sys directory of the file system. The driver directory depends on the version, for example under :

/sys/bus/i2c/drivers

The name of the camera driver usually refers to the sensor chip used.

 Examples for phyCAM Camera Modules and Driver Names

The type designations of other camera sensors can be found in the respective hardware manuals of the camera module.

The driver is accessed via the Video4Linux 2 interface (V4L2) of the camera driver from a separate application. Free multimedia frameworks such as the GStreamer can also access the driver via the V4L2 interface.

V4L2 functions which are supported by the drivers can be determined by Capability Querying. This mechanism and the description of the functions themselves are explained in the general descriptions for V4L2 (see Video for Linux Two API Specification).

In order to quickly test camera functions and display a camera image, it is advantageous to work with a simple tool.

For this purpose, PHYTEC provides scripts for the GStreamer, which is widely used in the Linux world. The GStreamer can be configured without programming effort by simple script calls. The scripts supplied by PHYTEC use the GStreamer to display and transfer image data streams. Furthermore, single images or image sequences can be saved in different formats.

These scripts also show how the GStreamer examples can be extended to include access to the camera registers. The desired configuration can be set by the user in an editable text file by selecting and deselecting the register accesses. An extension of the file by the user is also possible.

This procedure is explained in a separate document:

     LAN-052-d_AppNote_Set_Cam_Register

Depending on the BSP version, there are many other programs and programming examples, for example:

• ...\v4l2_c-examples\...
  (Access to the v4l2 interface from own C - programs)
• ...\opencv_examples\...
  (Access to the v4l2 interface from OpenCV)
• ...\gstreamer_examples\tools\...
  (Access to the registers of the camera modules via the I²C bus)

Basic Principles

General Access to the Camera Registers

General Access under Linux

To access the camera registers, the V4L2 API VIDIOC_DBG_G_REGISTER and VIDIOC_DBG_S_REGISTER are available.

In the PHYTEC distribution, the supplied camera drivers have already been created in debug mode.

The register functions can be integrated by the user into his own application. Prior to such an integration, it is advantageous to test the effect of certain register settings and make them visible with simple tools.

Setting the Camera Registers Using a Configuration File

During initial operation or when adapting the camera properties to an application, it is not only advantageous to set individual camera registers, but several camera registers in one step.

For this purpose, PHYTEC provides a configuration file and the corresponding tools to use this file. This file can be edited and adapted by the user himself.

Structure of the Configuration File

PHYTEC provides a sample configuration file as a TXT file for the corresponding camera. The name is freely selectable. The structure of the file is predefined.
For easy differentiation, PHYTEC has integrated the name of the sensor into the file name.

Examples:

• „register-settings-mt9v022.txt“ (for VM-007)
• „register-settings-mt9m001.txt“ (for VM-006)
• „register-settings-mt9m131.txt“ (for VM-009)

The structure of a register access is as follows.

chip-address, register-address, value, [mode]

chip-address = I²C base address of the camera sensor,
                        Format: hexadecimal 8-bit (mt9v022 = 0x48 / mt9m001 = 0x5d)
register-address = Address of the register to be changed in the camera.
                              Format: hexadecimal 8-bit
value = value to be written into the register
             Format: optionally hexadecimal 16-bit (0x...) or decimal
mode = Enables logical linking of the current register content with the specified value (optional).
              Possible parameters:
                   a (and, logical AND operation)
                   o (or, logical OR operation)
                   x (xor, logical exclusive OR operation)

The # character introduces a comment. This means that the selection or deselection can be done with a "#" in front of the line.

Many different options are already included in the camera sensor examples prefabricated by PHYTEC.

In the following, the gain value (electrical signal amplification) of the MT9V022 will be set to the factor x2. The # sign in the corresponding lines has been removed for this purpose.

---------------------------
#  set MT9V022 AGC
#  ===============
#  set AGC automatic
#0x48,0xAF,0x0002,o	# automatic = on

#  set AGC manual
0x48,0xAF,0xFFFD,a	# automatic = off
#0x48,0x35,0x0010	# set gain = 1.00
#0x48,0x35,0x0014	# set gain = 1.25
#0x48,0x35,0x0018	# set gain = 1.50
#0x48,0x35,0x001C	# set gain = 1.75
0x48,0x35,0x0020	# set gain = 2.00
#0x48,0x35,0x0024	# set gain = 2.25
#0x48,0x35,0x0028	# set gain = 2.50
#0x48,0x35,0x002C	# set gain = 2.75
#0x48,0x35,0x0030	# set gain = 3.00
…
---------------------------

After using the modified script file, the image is generated with a fixed gain value (Gain = 2,00). Further settings such as switching off the AEC and the automatic BLC can be found in the example settings supplied by PHYTEC.

Further descriptions of the register assignments of the camera sensors can be found on the homepage of the corresponding camera sensor manufacturer (mt9m001, mt9v022 see www.onsemi.com).

The sample configuration file for the various camera sensors can be found for:

• Linux directly in the directory where the example scripts for the GStreamer are stored:

…/gstreamer_examples/… 

chip-address, register-address, 0xFF00,a # unteres Byte löschen
chip-address, register-address, 0x0035,o # Wert 0x35 dort 
einschreiben

Using the Configuration File under Linux

Access via GStreamer

The scripts supplied by PHYTEC show how the GStreamer examples can be modified to include access to the camera registers. The desired configuration can be set by the user in the editable text file by selecting and deselecting the register accesses. Users can also modify the file.

Prerequisites

GStreamer - Plug-in for direct register access (part of the PHYTEC distribution).

Integrating the Configuration File under Linux

The PHYTEC script with the GStreamer example for taking a single jpeg image from the VM-012-BW camera module (VITA1300) in black/white is selected as the starting point ("vita1300_bw_save_jpg_full_res.sh").
Contents (abbreviated)

---------------------------
echo "start gstreamer"
echo "==============="

gst-launch-1.0 \
	v4l2src num-buffers=$NUMBER_OF_PIC device=$IPU1_CSI0_DEVICE ! \
	i2c file=`dirname $0`/../register-settings-vita1300.txt show=0 dev=$CAM_DEVICE ! \
	video/x-raw,format=GRAY8,depth=8,width=1280,height=1024 ! \
	vita1300_remapper mode=0 passthrough=false ! \
	videoconvert ! \
	jpegenc ! \
	multifilesink location=bw_$CAMERA.jpg
---------------------------

This example takes a picture "bw_VM-012(vita1300).jpg" in jpeg format. The camera sensor VITA1300 works in default mode with automatic settings AGC/AEC and automatic BLC.

In order to be able to set certain registers, the plug-in, which can process the desired I²C registers from a file, must also be listed.
The plugin "i2c file=[name of the text file] show=0 dev=$CAM_DEVICE! \" is placed between the initialization and the image request.

---------------------------
	…
V4L2src num-buffers=1 ! \
	i2c file=`dirname $0`/../register-settings-vita1300.txt show=0 	dev=$CAM_DEVICE ! \
	video/x-raw-gray$FRAME_SIZE ! \
	…
---------------------------

The specified text file ( "register-settings-vita1300.txt") is located in the gstreamer root directory. The setting "show=1 causes an additional output of the register accesses on the serial interface.

Further parameters of the "i2c"-Plugin are listed by entering the command "gst-inspect i2c".

i2c addr=0x48 file=register-settings-vita1300.txt show=0 dev=/dev/video0 ! \
i2c addr=0x4c file=register-settings-vita1300.txt show=0 dev=/dev/video1 ! \

Revision History