5.7.2 Over-the-Air (OTA) DFU Procedure

The Over-the-Air (OTA) firmware upgrade is a protocol that allows Bluetooth® Low Energy devices to receive a firmware image over the air from another Bluetooth Low Energy device. Microchip-defined OTA profile and service enables firmware upgrades over the Bluetooth Low Energy link using Generic Attribute Profile (GATT). The Bluetooth Low Energy OTA protocol defines the communication between the OTAU target and the OTAU manager. The OTAU manager can be a mobile device (iOS/Android) or any Bluetooth Low Energy device that implements the OTA GATT client protocol that transfers the upgrade firmware to the OTAU target. The OTAU target implements the OTA GATT server protocol to receive the new firmware image.

The OTA Device Firmware Update (DFU) process described combines the HOST OTA DFU and serial DFU methods to ensure a secure and reliable firmware upgrade for the RNBD350 device.

For more details about the serial DFU , refer to Serial DFU Procedure.

For more details about the HOST DFU, refer to Host OTA DFU through RNBD350.

The process begins when an OTAU (Over The Air Update) manager, typically a mobile device, initiates the HOST OTA DFU by sending the new firmware image to a host device, which can be a computer or another dedicated hardware. The RNBD350 acts as a gateway, transferring the incoming firmware from the OTAU manager to the host device, where it is stored safely. After that, the user must initiate a serial DFU to write the saved image onto the RNBD350. Consequently, the firmware inside the RNBD350 is upgraded. The OTA DFU in the RNBD350 represents a hybrid approach, integrating both the HOST DFU and serial DFU processes.

This approach strictly recommends having a successful and secure Bluetooth Low Energy link connection between two devices. Here, a peer device (OTA client profile) initiates a DFU request to the remote device requesting a device firmware update. For the detail demo procedure, refer to OTA DFU Process.