# dualbank – DUALBANK Module¶

The dualbank module adds ability to update and switch between the two app partitions.

There are two identical partitions, these contain different firmware versions. Having two partitions enables rollback functionality.

The two partitions are defined as boot partition and next-update partition. Calling dualbank.flash() writes the next-update partition.

After the next-update partition is written a validation check is performed and on a successful validation this partition is set as the boot partition. On next reset, firmware will be loaded from this partition.

Here is the sequence of commands to follow:

import dualbank

dualbank.flash(buffer, offset)
dualbank.switch()

dualbank.flash(*buffer: ReadableBuffer, offset: int = 0)None

Writes one of two app partitions at the given offset.

This can be called multiple times when flashing the firmware in small chunks.

dualbank.switch()None

Switches the boot partition.

On next reset, firmware will be loaded from the partition just switched over to.