CM4-ETH-RS485-BASE-B
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Introduction
Detailed parameter and function description.
Product Description
It is CM4-ETH-RS485-BASE-B, which is an expansion board that can be used with Raspberry Pi Compute Module 4, and supports a 7-36V DC power supply and 5V DC power supply of Type-C interface. Onboard four isolated RS485 interfaces, 100M+1000M dual network ports, HDMI interface, two CSI interfaces, two USB interfaces, etc...
Precautions for use
- Do not plug and unplug any device except USB and HDMI when it is powered on.
- Confirm the fan voltage before connecting, only support 5V.
- The Type C interface can be used as a power supply or as a USB interface to flash the image (need to use the DIP switch to switch).
- To ensure the normal power supply of CM4, please do not connect other devices when using the Type C interface to flash the image.
- When CM4 is in normal use, it needs to provide a 5V 2A power supply for CM4. Otherwise, there may be problems such as automatic shutdown, frequency reduction, and so on.
- USB2.0 is closed by default, if you need to open it, you need to add dtoverlay=dwc2,dr_mode=host in config.txt.
Product Size
CM4-ETH-RS485-BASE-B
Compute_Module 4 core board
Onboard Resources
Interfaces
| Label | Name | Description |
| 1 | CM4 connector | Applicable to all versions of Compute Module 4 |
| 2 | IO-VREF | Select GPIO logic voltage, selectable 3.3V (default) or 1.8V |
| 3 | RTC-I2C: I2C bus selection for RTC | Optional SDA0 & SCL0 (default) or GPIO2 & GPIO3 |
| 4 | RTC INT: RTC Interrupt pin selection | D16: RTC Use GPIO16 to receive interrupt signal when interrupt (default) GL-EN: CM4 is powered off when RTC interrupts |
| 5 | SYSTEM: System Function | WP-DIS: Prevent EEPROM from being overwritten BT-DIS: Disable Bluetooth function, only works on CM4 with an antenna |
| 6 | BOOT Switch | ON: Boot as USB Type-C interface OFF: Boot to eMMC or Micro SD card |
| 7 | PWR & USB | When the BOOT switch is "ON", it can be used as a programming port and a power supply interface When the BOOT switch is "OFF", it is only used as a power supply interface |
| 8 | HDMI0 | HDMI Display interface, support 4K 30fps output |
| 9 | USB | 2x USB2.0 interface, support connecting to USB devices |
| 10 | ETHERNET0 | CM4 Gigabit RJ45 Ethernet port |
| 11 | ETHERNET1 | USB expansion 100M Ethernet port |
| 12 | CAM0 & CAM1 | 2x MIPI CSI camera interfaces |
| 13 | Buzzer | GPIO22 control |
| 14 | FAN | Four-wire fan interface, only supports 5V fans, PWM speed regulation (GPIO18 control, no speed measurement) |
| 15 | RTC Battery interface | can be connected to the CR1220 button battery |
| 16 | RS485 Transceiver indicator | TXn: N channel transmitting indicator RXn: N channel receiving indicator |
| 17 | User LED indicator | USER0: GPIO20 control USER1: GPIO26 control |
| 18 | PWR | Raspberry Pi power indicator |
| 19 | ACT | Raspberry Pi working status indicator |
| 20 | DC 7~36V | DC power supply interface |
| 21 | Power supply terminal | DC power supply terminal, support 7~36V wide voltage input |
| 22 | RS485 Terminal | 4-ch isolated RS485 interface, 5.08mm pitch |
| 23 | Jumper Cap | Optional 120R Balance Resistor Jumper Cap |
| 24 | RS485 mode switch | Full-auto: automatic mode, the demo operation is simple, the load capacity is weak Semi-auto: semi-automatic mode, need to manually switch the transceiver mode, higher reliability, larger load capacity |
| 25 | Encryption chip | ATSHA204 encryption chip, supports multiple encryptions to ensure data security and reliability |
| 26 | Micro SD card slot | For inserting a Micro SD card with the system to boot the Compute Module 4 Lite |
How to Use
Precautions
Do not plug or unplug any device while it is powered on.
Image Flashing
USB 2.0
USB2.0 is disabled by default, if you want to enable it, you need to add dtoverlay=dwc2,dr_mode=host in config.txt.
RS485
New System
It is turned off by default. To turn it on, you need to add the following content in config.txt:
sudo nano /boot/config.txt
dtoverlay=uart3 dtoverlay=uart4 dtoverlay=uart5
COM1 occupies GPIO4/GPIO5 (BCM code 4/5), the device number is ttyAMA1
COM2 occupies GPIO8/GPIO9 (BCM code 8/9), the device number is ttyAMA2
COM3 occupies GPIO12/GPIO13 (BCM code 12/13), the device number is ttyAMA3
COM0 executes:
sudo raspi-config Go to Interface Options --> Serial Port --> <No> --> <Yes> Turn off the serial port login, and turn on the hardware serial port Reboot
COM0 occupies GPIO14/GPIO15 (BCM code 14/15), the device number is ttyS0
Old System
It is turned off by default. To turn it on, you need to add the following content in config.txt:
sudo nano /boot/config.txt
dtoverlay=uart0 dtoverlay=uart3 dtoverlay=uart4 dtoverlay=uart5
COM0 occupies GPIO14/GPIO15 (BCM code 14/15), the device number is ttyAMA0
COM1 occupies GPIO4/GPIO5 (BCM code 4/5), the device number is ttyAMA3
COM2 occupies GPIO8/GPIO9 (BCM code 8/9), the device number is ttyAMA4
COM3 occupies GPIO12/GPIO13 (BCM code 12/13), the device number is ttyAMA5
If other serial ports are enabled, they need to be commented out to to be turned off, for example:< br>
#enable_uart=1
Note: The default is automatic mode, and the sending and receiving mode is automatically switched. You can modify the 0R resistance on the back if program control of sending and receiving is required.
- Mode switching: Each channel is controlled by two 0R resistors
- Semi-automatic mode: The 0R resistors are on the "Semi-auto" end, and the user program controls the transceiver mode. (The following figure is in Semi-automatic mode.)
- Full-automatic mode: The 0R resistors are on the "Full-auto" end, and the transceiver mode is automatically switched according to the transmission direction.
RTC
To enable I2C to connect to the RTC controller, you need to set the dtparam=i2c_vc=on configuration file. RTC is on i2c-10, address is 0 x 51 (7-bit address).
sudo nano /boot/config.txt #Add at the end dtparam=i2c_vc=on #Add # in front of dtparam=audio=on #dtparam=audio=on #Save and exit, restart sudo reboot
Demo Download
Open the Raspberry Pi terminal and execute the following commands:
sudo apt-get install p7zip-full sudo wget https://files.waveshare.com/upload/4/42/PCF85063_code.7z 7z x PCF85063_code.7z -O./ cd PCF85063_code
C Code
Execute the following instructions to compile and execute the test the demo:
cd c sudo make clean sudo make -j 8 sudo ./main
The experimental phenomenon is as follows:
Python
Enter the Python program directory:
cd python/example
Run the demo, the program supports python2/3
# python2 sudo python main.py # python3 sudo python3 main.py
The experimental phenomenon is as follows:
FAN Test
- Support PWM speed regulation, no speed detection function.
- Note: Before connecting, please confirm the fan voltage and the power supply of the actually connected fan.
Open the Raspberry Pi terminal and execute the following commands:
wget https://files.waveshare.com/upload/d/d1/CM4-ETH-RS485-BASE-B-Example.zip unzip CM4-ETH-RS485-BASE-B-Example.zip -d ./CM4-ETH-RS485-BASE-B-Example cd CM4-ETH-RS485-BASE-B-Example/FAN/
C Code
Compile and execute the test demo.
cd c sudo make clean sudo make sudo ./main
Phenomenon: Enter the duty cycle as prompted to change the fan speed.
Python
Enter the Python demo directory:
cd python
Run the demo, and the demo supports python2/3.
# python2 sudo python FAN.py # python3 sudo python3 FAN.py
Phenomenon: first press the prompt to input the frequency, 5K is recommended, and then cycle the input duty cycle to change the fan speed.
CSI
The following are general instructions for CM4, specific devices differ: this module has no DSI interface and only HDMI0.
CSI DSI
New Version (Bookworm)
The DSI screen is 800x480 resolution screen by default, please refer to the corresponding WIKI for other resolution screens
When using the official base board Compute Module 4 IO Board, note that the J6 jumper cap needs to be connected
DSI
#Add the following to the config.txt file: sudo nano /boot/firmware/config.txt #DSI0 (V1~V3) dtoverlay=vc4-kms-dsi-7inch,dsi0 #DSI1 (V4) dtoverlay=vc4-kms-dsi-7inch,dsi1
CSI
| Mode | CAM0 setup statement | CAM1 setup statement |
|---|---|---|
| OV9281 | dtoverlay=ov9281,cam0 | dtoverlay=ov9281,cam1 |
| IMX290/IMX327 | dtoverlay=imx290,clock-frequency=37125000,cam0 | dtoverlay=imx290,clock-frequency=37125000,cam1 |
| IMX378 | dtoverlay=imx378,cam0 | dtoverlay=imx378,cam1 |
| IMX219 | dtoverlay=imx219,cam0 | dtoverlay=imx219,cam1 |
| IMX477 | dtoverlay=imx477,cam0 | dtoverlay=imx477,cam1 |
| IMX296 | dtoverlay=imx296,cam0 | dtoverlay=imx296,cam1 |
| IMX708 | dtoverlay=imx708,cam0 | dtoverlay=imx708,cam1 |
sudo reboot
Note:
1. The single-port camera can only work on CAM0, that is, it is not possible to use CAM1 port alone. But you can use the CAM0 port alone, or connect the dual cameras 2. If the device is recognized, and the startup prompt "Camera frontend has timed out!" appears, please update "sudo rpi-update"
Test Camera
- Enter the camera detection command, and you can see that the camera has been detected
libcamera-hello --list-cameras
- Display the camera screen to the desktop
libcamera-hello -t 0
- Take a photo
libcamera-jpeg -o test.jpg
- Record a 10s video
libcamera-vid -t 10000 -o test.h264
Other commands
Check if the camera is detected
libcamera-hello --list-cameras
Open the corresponding camera
libcamera-hello --camera 1 libcamera-hello --camera 0
Take a photo
libcamera-jpeg -o test.jpg #You can add --camera to specify the camera
#The new system uses dual cameras #Remove camera_auto_detect=1 in config.txt #camera_auto_detect=1 #Add dtoverlay=imx219,cam1 dtoverlay=imx219,cam0 #Where imx219 is the camera sensor model and other sensors are supported dtoverlay=ov5647,cam0 dtoverlay=imx219,cam0 dtoverlay=ov9281,cam0 dtoverlay=imx477,cam0 dtoverlay=imx519,cam0 #Then reboot reboot #Open camera libcamera-hello -t 0 or libcamera-hello #Other instructions: #Check if the camera is detected libcamera-hello --list-cameras #Open the corresponding camera, preview for 5 seconds libcamera-hello --camera 1 libcamera-hello --camera 0 #Take photos libcamera-jpeg -o test.jpg #Shoot video libcamera-vid -t 10000 -o test.h264 #You can add --camera to specify the camera #-t <duration> option allows the user to choose how long the window is displayed in milliseconds
For more commands, you can click here.
- Note: If using a DSI interface display there will be an HDMI disabled, even if just compiling the corresponding file without connecting a DSI screen.
- Connecting either HDMI port will allow output of an image, regardless of which HDMI port is used. If two HDMI screens are connected, only HDMI0 has an image output.
- To enable two HDMI ports, remove the configuration from config.txt:
- And then reboot it.
Please refer to Raspberry Pi manual.
Old System Version (Buster and Bullseye)
Configure Files
CSI and DSI are disabled by default. When using the camera and DSI, three I2C devices, I2C-10, I2C-11, and I2C-0 will be occupied.
Booting is performed 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/ #Execute (for version V1~V3) sudo dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp0-double_cam.dts #Execute (for version V4) sudo dtc -I dts -O dtb -o /boot/dt-blob.bin dt-blob-disp1-double_cam.dts Add the following to the config.txt file: sudo nano /boot/config.txt Change dtoverlay=vc4-kms-v3d to dtoverlay=vc4-fkms-v3d #When using any DSI, HDMI1 has no image output, even if you are not connected to the DSI screen, as long as you compile the corresponding file, then HDMI1 will have no output #If you need to restore, delete the corresponding dt-blob.bin: sudo rm -rf /boot/dt-blob.bin #After execution, turn off the power and restart
Record Test
Connect to the camera and the DSI display:
1. Please make sure it is connected under powering off.
2. Connect to the power.
3. The display will be booted after waiting for a few seconds.
4. If it fails to boot, check whether /boot/dt-blob.bin exists, and reboot it if it exists.
Old Version (Buster)
The camera needs to run raspi-config, select Interfacing Options -> Camera -> Yes -> Finish -> Yes, reboot the system, open enable camera, and then restart to save the changes.
Test the Raspberry Pi camera.
Check the screen of the first connected camera:
sudo raspivid -t 0 -cs 0
Check the screen of the second connected camera:
sudo raspivid -t 0 -cs 1
Encryption
Onboard encryption chip, not enabled by default.
Please refer to the datasheet and official library for use: [1]
Resource
Provide a full set of documents, procedures, data sheets, etc.
Documentation
Schematic
3D Drawing
Demo
Software
FAQ
b) Check whether the /boot/dt-blob.bin file exists, if it cannot be used, please delete it.
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It is the ttyS0 instead. You can remove the line dtoverlay=uart0 and use the ttyS0 which is the ttyAMA0 before.
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I'm sorry that we do not provide 3D drawing for the case.
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