Spurious Resets

The development board may spuriously reset when under heavy load when running older versions of the system software. This can be due to processor-intensive software (see this issue) or when power-intensive peripherals are active (see this issue).

Updating the system image to the latest version can help to avoid these issues – see Flashing the System Image for instructions on how to do this.

If your development board does not unexpectedly reset during use then there is no need to take action. However, if it becomes an issue then the following information may be useful.

Power Related Resets

Power over USB 2 or USB 3 from a laptop or workstation is not enough to supply enough power during heavy load – even the upper current limit that USB 3 hosts can supply is lower than what some components on the development board may require in certain situations.

Using the USB power adapter supplied with the development kit to directly power the board should avoid power-related resets. This has the disadvantage that this makes the USB connection unavailable for communication with a workstation.

A properly-charged battery should also be able to supply enough power in all situations and is useful for handling transient spikes in the current load. It is also useful when you need to use the USB connection for communication with a workstation.

Only batteries meeting the specification given in Librem 5 Development Kit should be used to avoid safety issues.

If you decide to use a battery, note that Linux 4.18 does not include support for battery charging for the development board, so a charger will also be needed for charging the battery separately.

Overheating Resets

The board can overheat when under heavy load, particularly when compiling complex pieces of software. Later kernels than the one initially installed on the board tend to prevent this issue.

Some resets are caused by the system shutting down due to overheating. This can be verified by monitoring the /sys/class/thermal/thermal_zone0/temp file which contains temperatures measured in millidegrees Celsius. Consider using a cooling fan to ensure a steady flow of air over the CPU if the temperature regularly exceeds 80°C.