WiConnect which is built on top of WICED is in actual fact part of a larger sophisticated application framework installed on all ACKme modules. The framework provides a hardened bootloader, read/write file system, safemode recovery mechanism, and secure over-the-air (OTA) upgrade capability.
Secure OTA Upgrade
ACKme manages a secure online OTA server that offers each ACKme module with the ability to securely upgrade individual files, applications or an entire firmware bundle. The OTA command is used to upgrade module firmware using the OTA server on this port.
The OTA process is secured by industry standard TLS1.0/HTTPS using server and client certificates that forces
- ACKme devices to verify the identity of the ACKme OTA server; and
- The ACKme OTA server to verify the identity of each individual ACKme device.
Each ACKme device is uniquely identified by a 128-bit hardware universally unique identifier (UUID).
HTTPS is the same security your web browser uses to make secure transactions with your bank over the internet. ACKme adds an additional layer of security, since the ACKme OTA server checks the unique security certificate and hardware UUID of each ACKme device that requests an upgrade.
This is actually a major step away from the typical and open FTP implementation found in other solutions. These other solutions run the risk malicious firmware replacement that could cause problems in the field.
Safe mode operation is guaranteed in the unlikely event the module is configured in a way that causes repeated and/or unexpected reboots. The bootloader automatically switches to safe mode after eight exceptions occur with the offending boot application. Safe mode is indicated by the system.safemode variable.
Once in safe mode, the module runs the upgrade application. The upgrade app provides the ability to upgrade the firmware, or switch back to WiConnect using the upgrade_app
faults_reset command andsystem.boot_app variable.
The module may be factory reset using the factory_reset command or by holding the factory reset pin (GPIO 0 on all ACKme modules) high for more than 10 seconds through a hardware reset. After a successful factory reset, all variables are set to factory defaults and the module reboots. To avoid accidental factory reset, the Wi-Fi MAC address must be provided when calling the factory_reset command.