On the Apollo3 Blue MCU, what is the BLE subsystem?
The BLE subsystem implemented on Apollo3 is a fully integrated system which is accessed via the BLE interface block, and provides autonomous clock and power management. The subsystem has a 32-bit core which runs from a 32 MHz oscillator, and is dedicated to running the lower portion of the BLE stack with a standard Host Controller interface (HCI). This core does not support user programming, as all user code runs on the main Cortex M4 processor. Software leverages the fully HCI compliant interface for Bluetooth operation. A series of proprietary HCI commands are also leveraged to provide additional performance and low power operation.
The BLE controller and host can be configured to support up to seven simultaneous connections on chip revision A1 (4 on chip revision B0). Secure connections and extended packet length are also supported.
See the Apollo3 Datasheet for a full description of the BLE subsystem.