Design review: Field device management

[krook]

Implement a plan to support existing devices in the field with new versions.

It is common that devices already deployed to customers will require updates for new functionality, bug fixes, device improvements, or security patches. It is critical that these updates are able to be deployed in the field, by a customer. Otherwise, support of the product over its lifetime becomes difficult.

It is recommended that a secure bootloader is included, such as mcuboot, and a device management layer (such as mcumgr) which allows transport of new firmware images should be included in the application firmware. The transport protocol would ideally be Bluetooth since the device is already expected to connect to a mobile phone through this interface. This interface can also be used to download log files or retrieve device statistics.