How to Use the Command 'vcgencmd' on Raspberry Pi (with examples)

The vcgencmd command is a powerful utility available on Raspberry Pi systems that allows users to query various pieces of system information directly from the VideoCore GPU. It is an essential tool for Raspberry Pi enthusiasts and developers who wish to monitor and extract detailed data about the hardware and its current status. The command can fetch details like temperature, voltage, throttle status, and more, which is invaluable for debugging, system optimization, and ensuring the smooth operation of Raspberry Pi projects.

Use case 1: List all available commands

Code:

vcgencmd commands

Motivation: Understanding the full range of available commands provided by vcgencmd is crucial for Raspberry Pi users who want to explore the comprehensive capabilities of the system. By listing all commands, users can see what information they can access and leverage for their respective applications, especially for troubleshooting or system diagnostics.

Explanation: The argument commands is a directive to vcgencmd asking it to output all possible commands that it can execute. This overview acts as a command reference guide providing insights into the different types of data that can be retrieved from the system.

Example Output:

commands="vcos, arbiter, properties, ...
clock_measure, measure_temp, measure_volts, get_throttled, bootloader_config, ..."

Use case 2: Print the current CPU temperature

Code:

vcgencmd measure_temp

Motivation: Monitoring the CPU temperature is vital for maintaining the health and performance of your Raspberry Pi. High temperatures could lead to thermal throttling, where the CPU slows down to prevent overheating. Regular temperature checks can help prevent this and extend the lifespan of the device.

Explanation: The argument measure_temp instructs vcgencmd to fetch and display the current temperature of the CPU. This provides real-time awareness of the device’s thermal condition.

Example Output:

temp=45.2'C

Use case 3: Print the current voltage

Code:

vcgencmd measure_volts

Motivation: Voltage monitoring is essential for diagnosing hardware issues. Under-voltage can cause system instability, leading to unexpected shutdowns or data corruption. Ensuring stable power supply levels helps in maintaining reliable system operations.

Explanation: The argument measure_volts is utilized to query the current voltage level supplied to the Raspberry Pi. Keeping track of this ensures that the Pi operates within safe electrical parameters.

Example Output:

volt=1.2000V

Use case 4: Print the throttled state of the system as a bit pattern

Code:

vcgencmd get_throttled

Motivation: Checking the throttled state provides insights into whether the Raspberry Pi has hit any performance or power supply limits. Throttling occurs to protect the system from overheating or unstable power conditions. Understanding this is crucial for performance tuning and problem diagnosis.

Explanation: The command get_throttled returns a bit pattern indicating the current and past throttling states. Each bit represents a specific status, such as under-voltage detected or frequency-capping due to overheating. This data can be decoded to assess system limitations that occurred at runtime.

Example Output:

throttled=0x0

Use case 5: Print the bootloader configuration (only available on Raspberry Pi 4 models)

Code:

vcgencmd bootloader_config

Motivation: Examining the bootloader configuration is essential for understanding how your Raspberry Pi initializes during the boot process. On Raspberry Pi 4 models, it allows users to tweak and ensure that settings align with their specific requirements or if customization is needed for particular hardware configurations.

Explanation: The bootloader_config argument triggers vcgencmd to display the settings configured in the bootloader. This information can elucidate on startup preferences and other system-level configuration attributes.

Example Output:

[all]
BOOT_UART=0
WAKE_ON_GPIO=1
POWER_OFF_ON_HALT=0

Use case 6: Display help

Code:

vcgencmd --help

Motivation: Accessing the help option is invaluable for users who are not familiar with the vcgencmd syntax and options. It offers an accessible introduction to new users and acts as a reminder for experienced ones about the available features and their usage.

Explanation: The --help argument is a universal directive that commands the system to provide a help message. This output guides users on the basic syntax and available commands, supporting effective command utility use.

Example Output:

vcgencmd [<opt>]+
   commands        list all available commands
   measure_temp    display current CPU temperature
   ...

Conclusion

The vcgencmd command is a versatile tool that facilitates in-depth Raspberry Pi system information retrieval. From monitoring temperature and voltage to examining throttled status and bootloader configurations, each of these use cases plays a critical role in system diagnostics, optimization, and maintenance. By understanding and utilizing vcgencmd, Raspberry Pi users can better manage their devices and ensure they operate efficiently and effectively.