In the case of a Raspberry Pi, it is possible to do the boot the operating system from the microSD card inserted into the appropriate slot. With the new one Raspberry Pi 5you can, however, boot the system using a USB support external such as a thumb drive or SSD drive. Using a 5V/3A power supply, however, Raspberry Pi 5 shows a warning screen blocking the boot procedure. In this article we will see what it is and how it can be overcome.
Raspberry recommends using the 5V/5A power supply
In the case of the Raspberry Pi 4 boards, the foundation suggested using a alimentatore 5V/3A. In the case of the new Raspberry Pi 5, the requirements have become a little more stringent. In fact, it is recommended to use a 5V/5A adapter with Raspberry which provides an original power supply.”Raspberry Pi 27W USB-C Power Supply“.
There is no obligation to use the 5V/5A power supply: however, if you try to start Raspberry Pi 5 from a USB device with a 5V/3A power supply, an alert message appears stating the following: “USB boot requires high current (5 volt, 5 amp) power supply“.
By carrying out a measurement of the currents and voltages involved, it is possible to ascertain that there are no problems when a 5V/5A power supply is not used. Provided, of course, that you do not use applications that put excessive strain on the USB port. If you plan to connect several devices to the USB port, the use of the 5V/5A power supply is essential.
Installing the operating system on USB media
To use Raspberry Pi 5 it is obviously necessary install the operating system. There are various ways to proceed in this sense; the standard approach however consists in using the Raspberry Pi Imager software which allows you to write the system image operating on a microSD card or USB storage medium.
Given the possibility of boot from USB with Raspberry Pi 5, the Pi Imager program can be used on a PC to configure any media to then connect with the single-board computer.
After downloading Pi Image from this page, just double-click on its executable to start its installation. From the drop-down menu Choose device will be chosen in this case Raspberry Pi 5 while as an operating system to be inserted into the bootable media you can opt for Raspberry Pi OS (64 bit). In another article we presented all the news about Raspberry Pi OS Bookworm, derived from it Debian.
With one click your Choose SD cardHowever, you should not select a microSD card connected to your system. Choosing one USB pendrive or a unit SSD connected to a USB port (make sure that the capacity is at least 16 GB in any case), you can make the media bootable and use it as an external device for booting from Raspberry Pi 5.
Setting up the operating system with basic configurations
When the message appears Do you want to apply operating system customization settings?we suggest clicking the button Change settings in such a way as to have the possibility to immediately define the name of the device, set personalized access credentials, specify the data for connection to the WiFi network and preferences in terms of time zone and keyboard layout.
Interestingly, by assigning administrator rights to the Pi Imager program, it is able to automatically extract the password WiFi from your system and set it in the installation preferences. By doing so, the Raspberry Pi 5 will automatically connect to the wireless network using the specified credentials.
In the tab Servicesit is possible to decide whether to enable the connection via SSH.
At the end of the USB support creation procedure you can connect it to the USB-A port available on the Raspberry Pi 5.
How to ignore the boot warning
If you were using a 5V/3A power supply, when the warning described above appears, just press the power button on the Raspberry Pi 5 once.
To avoid seeing the message appear every time, simply open the terminal window and then type the following, as explained on the Powering Raspberry Pi 5 page:
nano /boot/firmware/config.txt
At this point, just add the following directive to the contents of the configuration file and then save everything by pressing CTRL+O:
usb_max_current_enable=1
The key combination CTRL+X finally allows you to close the text editor nano.
Raspberry Pi 5 can keep time using a backup battery
The connector located between the USB-C port and the Micro HDMI on the Raspberry Pi 5 board (in the image RTC battery connector) allows you to connect a backup battery of type ML2032.
The structure of the board (image source: Raspberry Pi Foundation).
The card, in fact, relies on an NTP server (Network Time Protocol) which takes care of every start-up synchronize the clock of system. The date and time remain correct for as long as the Raspberry Pi remains powered (connected to the mains via a power supply).
When the power is removed, however, the card loses the correct date and time. Just by connecting a ML2032 buffer battery to the indicated connector, you can ensure that at the next start – even in the event of disconnection from the Internet or WiFi connection not working – Raspberry Pi keep the right time.
