Template: Cm4-disp-base-7a-box Guide

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Writing Image


USB2.0

The USB port is disabled by default on the CM4 for saving power. If you need to use it, you need to add the following to the config.txt file:

dtoverlay=dwc2,dr_mode=host

Then reboot the CM4

If you use the latest Raspberry Pi OS (image after October 30, 2021) USB2.0 is OTG mode by default, CM4 will report an error:

config failed, hub doesn't have any ports! (err -19)

However, USB can still workable. If you want to remove this error, please remove the line otg_mode=1 in [cm4] of config.txt, and add dtoverlay=dwc2, dr_mode=host (USB cannot be recognized without adding it).
CM4 Burn EMMC 12.png


I2C interface

Enable I2C Interface

Open a terminal and run the following commands:

sudo raspi-config 
Choose Interfacing Options -> I2C ->yes 

Reboot Raspberry Pi:

sudo reboot

RPI open i2c.png
There are two I2C address were used by the RTC and FAN, please avoid the address when connecting external i2c devices.

  • RTC: i2c-1 (0x51)
  • FAN: i2c-1 (0x2F)

RS485/RS232

They are disabled by default. If you need to use the RS485 or RS232, you need to modify the config.txt:

sudo nano /boot/config.txt<br>

And add the following lines:

dtoverlay=uart3
dtoverlay=uart5
<pre>
Then reboot the CM4 and check if the corresponding ports were recognized.
<pre>
reboot
ls /dev/ttyAMA*

RS232 occupies GPIO5/GPIO4 (BCM code 4/5), device number ttyAMA1
RS485 occupies GPIO13/GPIO12 (BCM code 13/12), device number ttyAMA2

RS485 can be switched to GPIO15/14 for device number ttyS0
Refer to number 27 of the Onboard Resources, change the corresponding resistance to the corresponding position

Test

  sudo apt-get install minicom
  # RS232
  sudo minicom -D /dev/ttyAMA1
  #RS485
  sudo minicom -D /dev/ttyAMA2

GPIO

The GPIO input/output interface only supports a single-mode and does not support switching. The following are the corresponding pins of the interface.
OUT CH1 GPIO17
OUT CH2 GPIO27
IN CH1 GPIO22
IN CH2 GPIO23

The module only supports 3.3V and 5V, which can be switched by jumper caps.

Audio

Add the following lines to config,txt

 dtparam=audio=on
 dtoverlay=audremap,pins_18_19
 audio_pwm_mode=2
 disable_audio_dither=1

Reboot the CM4 and check if the new play device is recognized by the command aplay -l
After it is turned on, it can be recognized under the audio selection. There may be a problem that the default sound card is not a GPIO sound card.

RTC FAN

  • Note: Please connect the fan before turning on the power of the expansion board and then complete the test. Please do not connect the fan after the expansion board has been powered on, otherwise the chip will be burned!

I2C-1 is used by default

RTC (PCF85063a) on i2c-1, address is 0x51 (7-bit address)
FAN (EMC2301) on i2c-1, address is 0x2f (7-bit address)

RTC

sudo nano /boot/config.txt
 #Add at the end
 dtparam=i2c_arm=on
 dtoverlay=i2c-rtc,pcf85063a
 #Save and exit, restart
 sudo reboot

Hwclock is simple to use

Synchronize System Clock -> Hardware Clock

sudo hwclock -w

Synchronize hardware clock -> system clock

sudo hwclock -s
 #The network needs to be closed, or the network pair is closed, or the clock will be changed back
 #This command is only for test use, please open it during actual use, the time is more accurate
 #Turn off network timing
 # sudo timedatectl set-ntp false
 #Enable network timing
 # sudo timedatectl set-ntp true

Set the hardware clock time:

sudo hwclock --set --date="9/8/2021 16:45:05"

Check hardware clock

sudo hwclock -r

Show version information

sudo hwclock --verbose


Fan

When powered on, the fan will spin for 1 second, then stop for 2 seconds, this is a normal
test driver

wget https://www.waveshare.com/w/upload/b/b9/EMC2301_i2c1_code.zip
unzip -o EMC2301_i2c1_code.zip -d ./EMC2301_i2c1_code
sudo chmod 777 -R EMC2301_i2c1_code
cd EMC2301_i2c1_code/
 
#C
cd c/
make
sudo ./main

#python
cd python/examples
sudo python main.py

Screen and camera turned on

If you use the buster system, you just need to add the configuration file and reboot.
If you use the new version (bullseye) system, additional modifications are required

Load Configuration File

When using the camera and DSI, it will occupy three I2C devices: I2C-10, I2C-11, I2C-0
The camera needs to run raspi-config, select Interfacing Options->Camera->Yes->Finish-Yes, reboot the system, open the enable camera, and then restart to save the changes.
Execute as follows:

wget https://www.waveshare.com/w/upload/7/75/CM4_dt_blob_Source.zip
 unzip -o CM4_dt_blob_Source.zip -d ./CM4_dt_blob_Source
 sudo chmod 777 -R CM4_dt_blob_Source
 cd CM4_dt_blob_Source/
 sudo dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp0-double_cam.dts
 # After execution, turn off the power and restart the CM4

Old Version (Buster)

Note: On December 2, 2021, the Raspberry Pi OS for Raspberry Pi split into two branches, the Buster branch, and the Bullseye branch.

The Buster branch is a continuation of the old system and is more stable. The Bullseye branch adds some new features, uses open source libraries and new interfaces.

If you use the Buster branch system, the image can be used normally without any modification. View the first connected camera screen:

sudo raspivid -t 0 -cs 0



New Version (Bullseye)

If you are using the Bullseye branch of the system, refer to the following

Show

Comment the following statements in the config.txt file (the config file is located in the root directory of the TF card, namely /boot):

#camera_auto_detect=1
#dtoverlay=vc4-kms-v3d

Add the following statement below [all]:

dtoverlay=vc4-fkms-v3d


After saving, restart the Raspberry Pi

sudo reboot

Camera

libcamera-hello -t 0
or
libcamera-hello

#The default camera model is ov5647, if you need to change it to other cameras, you can check the camera model by yourself
#Add to
dtoverlay=ov5647,cam1
dtoverlay=ov5647,cam0

#where ov5647 is the camera sensor model, and there are other sensors
dtoverlay=ov5647,cam0
dtoverlay=imx219,cam0
dtoverlay=ov9281,cam0
dtoverlay=imx477,cam0

#then restart
reboot

# another part of the command:
#Check if the camera is detected
libcamera-hello --list-cameras

#open camera
libcamera-hello --camera 0

#Taking Pictures
libcamera-jpeg -o test.jpg
#You can add --camera to specify the camera

More instructions click me
Reference Raspberry Pi Manual