9.3 Radio (RF Core)
The RF Core is a highly flexible and future proof radio module which contains an Arm Cortex-M0 processor that
interfaces the analog RF and base-band circuitry, handles data to and from the system CPU side, and
assembles the information bits in a given packet structure. The RF core offers a high level, command-based API
to the main CPU that configurations and data are passed through. The Arm Cortex-M0 processor is not
programmable by customers and is interfaced through the TI-provided RF driver that is included with the
SimpleLink Software Development Kit (SDK).
The RF core can autonomously handle the time-critical aspects of the radio protocols, thus offloading the main
CPU, which reduces power and leaves more resources for the user application. Several signals are also
available to control external circuitry such as RF switches or range extenders autonomously.
A Packet Traffic Arbitrator (PTA) scheme is available for the managed coexistence of BLE and a co-located 2.4-
GHz radio. This is based on 802.15.2 recommendations and common industry standards. The 3-wire
coexistence interface has multiple modes of operation, encompassing different use cases and number of lines
used for signaling. The radio acting as a slave is able to request access to the 2.4-GHz ISM band, and the
master to grant it. Information about the request priority and TX or RX operation can also be conveyed.
The various physical layer radio formats are partly built as a software defined radio where the radio behavior is
either defined by radio ROM contents or by non-ROM radio formats delivered in form of firmware patches with
the SimpleLink SDKs. This allows the radio platform to be updated for support of future versions of standards
even with over-the-air (OTA) updates while still using the same silicon.
9.3.1 Bluetooth 5.2 Low Energy
The RF Core offers full support for Bluetooth 5.2 Low Energy, including the high-sped 2-Mbps physical layer and
the 500-kbps and 125-kbps long range PHYs (Coded PHY) through the TI provided Bluetooth 5.2 stack or
through a high-level Bluetooth API. The Bluetooth 5.2 PHY and part of the controller are in radio and system
ROM, providing significant savings in memory usage and more space available for applications.
The new high-speed mode allows data transfers up to 2 Mbps, twice the speed of Bluetooth 4.2 and five times
the speed of Bluetooth 4.0, without increasing power consumption. In addition to faster speeds, this mode offers
significant improvements for energy efficiency and wireless coexistence with reduced radio communication time.
Bluetooth 5.2 also enables unparalleled flexibility for adjustment of speed and range based on application needs,
which capitalizes on the high-speed or long-range modes respectively. Data transfers are now possible at 2
Mbps, enabling development of applications using voice, audio, imaging, and data logging that were not
previously an option using Bluetooth low energy. With high-speed mode, existing applications deliver faster
responses, richer engagement, and longer battery life. Bluetooth 5.2 enables fast, reliable firmware updates.
9.3.2 802.15.4 (Thread, Zigbee, 6LoWPAN)
Through a dedicated IEEE radio API, the RF Core supports the 2.4-GHz IEEE 802.15.4-2011 physical layer (2
Mchips per second Offset-QPSK with DSSS 1:8), used in Thread, Zigbee, and 6LoWPAN protocols. The
802.15.4 PHY and MAC are in radio and system ROM. TI also provides royalty-free protocol stacks for Thread
and Zigbee as part of the SimpleLink SDK, enabling a robust end-to-end solution.
9.4 Memory
The up to 352-KB nonvolatile (Flash) memory provides storage for code and data. The flash memory is in-
system programmable and erasable. The last flash memory sector must contain a Customer Configuration
section (CCFG) that is used by boot ROM and TI provided drivers to configure the device. This configuration is
done through the ccfg.c source file that is included in all TI provided examples.
The ultra-low leakage system static RAM (SRAM) is split into up to five 16-KB blocks and can be used for both
storage of data and execution of code. Retention of SRAM contents in Standby power mode is enabled by
default and included in Standby mode power consumption numbers. Parity checking for detection of bit errors in
memory is built-in, which reduces chip-level soft errors and thereby increases reliability. System SRAM is always
initialized to zeroes upon code execution from boot.
SWRS232D – FEBRUARY 2019 – REVISED FEBRUARY 2021
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Copyright © 2021 Texas Instruments Incorporated
