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

Writing Image

USB2.0

The USB port is disabled by default on the CM4 to save 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 be 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).

Enable I2C Interface

Open a terminal and run the following commands:

sudo raspi-config 
Choose Interfacing Options -> I2C -> Yes.

Reboot Raspberry Pi:

sudo reboot

There are two I2C addresses 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

And add the following lines:

dtoverlay=uart3
dtoverlay=uart5

Then reboot the CM4 and check if the corresponding ports were recognized.

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, and 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.

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
Execute as follows:

wget https://files.waveshare.com/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 and 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

View the second connected camera screen:

sudo raspivid -t 0 -cs 1

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 new system uses dual cameras
#Remove or comment out the line camera_auto_detect=1 in config.txt
#camera_auto_detect=1

#Add the following lines:
dtoverlay=imx219,cam1
dtoverlay=imx219,cam0

#Add the corresponding line according to the camera you use, where imx219 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

#Other part of the commands:
#Check if the camera is detected
libcamera-hello --list-cameras

#Open the corresponding camera
libcamera-hello --camera 1
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

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 the following lines at the end
 dtparam=i2c_vc=on
 dtoverlay=i2c-rtc,pcf85063a,i2c_csi_dsi
 #Add # in front of dtparam=audio=on
 #dtparam=audio=on
 #Save and exit, restart
 sudo reboot

How to use Hwclock

Synchronize system clock to hardware clock

sudo hwclock -w

Synchronize hardware clock to system clock

sudo hwclock -s
 #The network or the NTP needs to be closed, otherwise it will be changed back.

Set the hardware clock time:

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

View hardware clock

sudo hwclock -r

Display version information

sudo hwclock --verbose

Fan

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

wget  https://files.waveshare.com/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

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