Skip to main content

USB Type-A / C Ports

The Radxa CM4 IO Board comes with the following USB ports:

  • 1 × USB 3.0 Type-C port
  • 1 × USB 3.0 Type-A port
  • 2 × USB 2.0 Type-A ports

USB 3.0 Type-C Port​

  • Supports both OTG and HOST modes
  • Blue color-coded internal connector
  • Theoretical maximum transfer rate: 5Gbps

USB 3.0 Type-A Port​

  • Supports HOST mode only
  • Blue color-coded internal connector
  • Theoretical maximum transfer rate: 5Gbps

USB 2.0 Type-A Ports​

  • Support HOST mode only
  • Black color-coded internal connectors
  • Theoretical maximum transfer rate: 480Mbps

Hardware Connection​

Connect USB devices such as mice, keyboards, or flash drives to the USB Type-A/C ports. The Type-C port also supports OTG mode, which can be verified by enabling ADB functionality.

Port Location

Refer to the Hardware Information tutorial to locate the corresponding hardware interfaces.

HOST Mode​

To test the HOST mode functionality of the USB ports, you can verify basic device connectivity and measure flash drive read/write speeds.

Basic Functionality Test​

Connect devices like card readers, mice, or keyboards to test if they are properly recognized and functional.

Check Connected Devices (Before Connection)​

Use the lsusb command to view currently recognized USB devices.

radxa@device$
lsusb

Example output:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID a69c:8d81 AICSemi AIC 8800D80
Bus 001 Device 002: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Check After Connecting a Device​

After connecting a device (e.g., card reader, mouse, keyboard), run lsusb again to check for the new device.

radxa@device$
lsusb

Example output after connecting a card reader:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID a69c:8d81 AICSemi AIC 8800D80
Bus 001 Device 002: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 067b:2731 Prolific Technology, Inc. USB SD Card Reader

By comparing the outputs, you can confirm that the new USB device (ID: 067b:2731) has been properly recognized. Once recognized, you can proceed to test the device's functionality.

Read/Write Speed Test​

Connect a USB flash drive and use the dd command to test read/write speeds.

Identify the Storage Device​

Use lsblk to identify your flash drive's device name.

radxa@device$
lsblk

Example output (in this case, the flash drive is sda):

NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda           8:0    1   58G  0 disk
mtdblock0    31:0    0   16M  0 disk
mmcblk1     179:0    0   58G  0 disk
├─mmcblk1p1 179:1    0   16M  0 part /config
├─mmcblk1p2 179:2    0  300M  0 part /boot/efi
└─mmcblk1p3 179:3    0 57.6G  0 part /
zram0       253:0    0  1.9G  0 disk [SWAP]

Test Write Performance​

radxa@device$
sudo dd if=/dev/zero of=/dev/sda bs=1M count=100
  • dd: A command-line utility for copying and converting files in Linux
  • if=/dev/zero: Specifies the input file as /dev/zero, which provides an infinite stream of null bytes
  • of=/dev/sda: Specifies the output file as the USB flash drive (replace sda with your device)
  • bs=1M: Sets the block size to 1MB
  • count=100: Specifies to copy 100 blocks (total 100MB)

This command writes 100MB of zero bytes to the flash drive and displays the write speed.

Example output:

100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 3.40424 s, 30.8 MB/s

Test Read Performance​

radxa@device$
sudo dd if=/dev/sda of=/dev/null bs=1M count=100
  • dd: A command-line utility for copying and converting files in Linux
  • if=/dev/sda: Specifies the input file as the USB flash drive
  • of=/dev/null: Directs output to /dev/null, discarding all data
  • bs=1M: Sets the block size to 1MB
  • count=100: Specifies to copy 100 blocks (total 100MB)

This command reads 100MB of data from the flash drive and displays the read speed.

Example output:

100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 4.0582 s, 25.8 MB/s

OTG Mode​

Verify the OTG functionality of the Radxa CM4 by enabling ADB (Android Debug Bridge).

Enable ADB Functionality​

Use the rsetup tool to enable ADB functionality.

Using Rsetup

For more information about using Rsetup, refer to the Rsetup Usage tutorial.

radxa@device$
rsetup

Navigate to Hardware -> USB OTG services and enable the [email protected] option to activate ADB functionality.

Test OTG Functionality​

Connect your PC to the Radxa CM4's USB 3.0 Type-C port using a Type-C cable, then test the OTG functionality using ADB commands.

Install ADB Tools​

Linux$
sudo apt install adb

Check ADB Devices​

Use the adb devices command to list connected ADB devices.

Linux$
adb devices

Example output (showing one ADB device connected):

List of devices attached
0123456789ABCDEF	device

Test ADB Shell​

Access the Radxa CM4's terminal shell using the adb shell command.

Linux$
adb shell

If you successfully enter the Radxa CM4's terminal, the OTG functionality is working correctly. You can now use various commands to check system information on the Radxa CM4.

Interface Pin Definitions​

For detailed pin definitions, please refer to the hardware schematics available on the Downloads page.