BCM20705 Datasheet, PDF (25/67 Pages) Cypress Semiconductor – Single-Chip Bluetooth Transceiver and Baseband Processor

BCM20705 Data Sheet
Microprocessor Unit
Section 4: Microprocessor Unit
Overview
The BCM20705 microprocessor unit runs software from the Link Control (LC) layer up to the Host Controller
Interface (HCI). The microprocessor is based on the ARM7TDMIS 32-bit RISC processor with embedded ICE-
RT debug and JTAG interface units. The microprocessor also includes 448 KB of ROM memory for program
storage and boot ROM, 132 KB of RAM for data scratch-pad, and patch RAM code.
Note: The BCM20705A1KWFBG part only contains 384 KB of ROM and 112 KB of RAM.
The internal boot ROM provides flexibility during power-on reset to enable the same device to be used in various
configurations, including automatic host transport selection from SPI, USB, or UART, with or without external
NVRAM. At power-up, the lower layer protocol stack is executed from the internal ROM.
External patches can be applied to the ROM-based firmware to provide flexibility for bug fixes and features
additions. These patches can be downloaded from the host to the device through the SPI, USB, or UART
transports, or using external NVRAM. The device can also support the integration of user applications and
profiles using an external serial flash memory.
Broadcom®
Bluetooth Transceiver and Baseband Processor
November 13, 2014 • MCS20705-DS104-R
Page 24
BROADCOM CONFIDENTIAL