User Manual

Document ID: PB-ZB-MOD-003-20DS

3 COMPONENTS OVERVIEW

3.1 STM32W108 – SYSTEM-ON-CHIP

The is a fully The is a fully integrated System-on-Chip that integrates a 2.4 GHz, IEEE 802.15.4-compliant transceiver, 32-bit

ARM® Cortex™-M3 microprocessor, Flash and RAM memory, and peripherals of use to designers of ZigBee-based systems.

Block diagram of STM32W108 is show on Fig. 3.1 below:

Fig. 3.1 Block diagram of System-on-Chip STM32W108

The transceiver utilizes an efficient architecture that exceeds the dynamic range requirements imposed by the IEEE 802.15.4-

2003 standard by over 15 dB. The integrated receive channel filtering allows for robust co-existence with other communication

standards in the 2.4 GHz spectrum, such as IEEE 802.11 and Bluetooth. The integrated regulator, VCO, loop filter, and power

amplifier keep the external component count low. An optional high performance radio mode (boost mode) is software-

selectable to boost dynamic range.

The integrated 32-bit ARM® Cortex™-M3 microprocessor is highly optimized for high performance, low power consumption,

and efficient memory utilization. Including an integrated MPU, it supports two different modes of operation: System mode and

Application mode. The networking stack software runs in System mode with full access to all areas of the chip. Application

code runs in Application mode with limited access to the STM32W108 resources; this allows for the scheduling of events by

the application developer while preventing modification of restricted areas of memory and registers. This architecture results in

increased stability and reliability of deployed solutions.

The STM32W108 has 128 Kbytes of embedded Flash memory and 8 Kbytes of integrated RAM for data and program storage.

The STM32W108 HAL software employs an effective wear-levelling algorithm that optimizes the lifetime of the embedded

Flash.

To maintain the strict timing requirements imposed by the ZigBee and IEEE 802.15.4-2003 standards, the STM32W108

integrates a number of MAC functions into the hardware. The MAC hardware handles automatic ACK transmission and

reception, automatic back off delay, and clear channel assessment for transmission, as well as automatic filtering of received

packets. A packet trace interface is also integrated with the MAC, allowing complete, non-intrusive capture of all packets to

and from the STM32W108.

The STM32W108 offers a number of advanced power management features that enable long battery life. A high-frequency

internal RC oscillator allows the processor core to begin code execution quickly upon waking. Various deep sleep modes are