Software Architecture

The TI royalty-free Zigbee protocol stack is a software component in the CC23xx SDK for developing single-mode Zigbee standalone and network processor applications. This component is based on the SimpleLink CC23xx family of Zigbee enabled wireless MCUs. The CC23xx combines a 2.4-GHz RF transceiver, in-system programmable flash memory and SRAM in the CC23xx, and a full complement of peripherals. The CC23xx wireless MCU is centered on an Arm® Cortex®-M series processor that handles the application layer and Zigbee protocol stack, as well as low-level radio control and processing associated with the physical layer (PHY).

Warning

As CC23xx is a mono-core device (i.e. no separate radio core), processing inside HWIs and SWIs may impact the timing of scheduled radio commands. TI recommends to keep any code executed in HWIs and SWIs short. For example, it is advisable to post an event to handle further, potentially lengthy processes rather than handle them in the HWI/SWI context.

For more information on the CC23xx, see the CC23xx SimpleLink Wireless MCU Technical Reference Manual.

Zigbee 3.0 Protocol Stack and Application Configurations

The Zigbee 3.0 stack platform supports two different protocol stack and application operational configurations:

  • Single device: The Zigbee applications are all implemented on the wireless MCU as a true single-chip solution. This configuration is the simplest and most common when using the CC23xx. This configuration is used by most of TI’s sample projects. This configuration is the most cost- effective technique and provides the lowest-power performance.

  • Network processor: The Zigbee networking reside on the wireless MCU with the application and profile residing on an external application processer (AP). Communication with the wireless MCU occurs over a UART interface using the serialized Network Processor Interface (NPI) protocol. Using NPI, the AP controls the network processor with Zigbee commands. The network processor option is ideal for adding Zigbee protocol to an existing non-wireless application.

Solution Platform

This section describes the various components that are installed with Zigbee 0.95.00 and the directory structure of the protocol stack and any tools required for development.

Figure 17. shows the Zigbee 3.0 development system. Unless otherwise noted, Zigbee 3.0 applications must be built with components from this CC23xx SDK.

../_images/fig-cc23xx-sw-architecture.png

Figure 17. Zigbee Stack Development System

The solution platform includes the following components within the CC23xx SDK:

  • TI Drivers provides a device register abstraction layer and is used by software and Driverlib to control the CC23xx at the lowest level.

  • The protocol stack is provided in library form with parts of the protocol stack stored in the CC23xx’s flash.

  • Sample applications and profiles make starting development Zigbee application using both custom and adopted solutions easier.

The following integrated development environments (IDEs) are supported:

  • Code Composer Studio™ (CCS) using the TI Clang Compiler

Refer to the SDK release notes for the specific IDE & toolchain versions supported by this release.

Zigbee Software Architecture

The CC23xx Zigbee software environment consists of the following parts:

  • An application with the FreeRTOS kernel, TI Drivers, and Zigbee profile

  • A Zigbee 3.0 library that implements Zigbee protocol

Some examples implement these as two separate projects. In some examples the stack is prebuilt and linked as library files.

FreeRTOS is an open-source, real-time operating system kernel for embedded devices. It implements a minimalist set of functions, basic task handling and memory management.

Single Project Configuration

In Zigbee 0.95.00, stack is pre-built as a library that is statically linked to the application. This saves a build step compared to using a stack library configuration project. See the example project’s README file for the available project build configurations.

Stack library projects have the following properties:

  • Stack provided as pre-build library files

  • Application project will link the stack library files

  • There is no explicit app/stack boundary. The application’s link step decides the memory locations of the code within the stack library.

  • This architecture saves flash by allowing the linker work more efficiently.

Working With Hex and Binary Files

Zigbee 3.0 projects within this SDK are configured to produce an Intel-extended hex file in their respective output folders. These hex files can be programmed individually with a compatible flash programming tool, such as UniFlash. To simplify the flash programming process, you can combine the application with other Intel-extended hex files into a super hex file manually or using freely available tools provided the individual hex files lack overlapping memory regions. Information on the Intel Hex standard.

One method for creating the super hex file is with the IntelHex python script hex_merge.py, available at the IntelHEX Canonical page. To merge the hex files, install Python® 2.7.x and add it to your system path environment variables.

Warning

Note that when using any python script, you must use a compatible version of Python. Refer to the tool documentation or contact the developer to verify compatibility.

If conversion of the super hex to a binary file is desired, this can be accomplished with the “hex2bin.py” or similar tools that support the hex standard.

1C:\Python27\Scripts>python hex2bin.py \
2    basic_zigbee_super.hex \
3    basic_zigbee_super.bin

Programming Internal Flash with the ROM Bootloader

The CC23xx internal flash memory can be programmed using the bootloader in the ROM of the device. Both UART and SPI protocols are supported. For more details on the programming protocol and requirements, see the Bootloader chapter of the CC23xx SimpleLink Wireless MCU Technical Reference Manual.

Note

Because the ROM bootloader uses predefined DIO pins for internal flash programming, allocate these pins in the layout of your board. For details on the pins allocated to the bootloader based on the chip package type, see CC23xx SimpleLink Wireless MCU Technical Reference Manual.