User's Manual

DFZM-E72xx
Data Sheet Sheet 8 of 40 Sep 16, 2013
Proprietary Information and Specifications are Subject to Change
3-2.Block Diagram Description
3-2-1.Overview
DFZM-E72xx module is a highly integrated ZigBee system-on-chip (SOC) that contains the following:
• The module includes Silicon Labs EM357 SoC, which contains CPU- and memory-related,
peripherals-related, clocks and power management-related in a single package.
• The module features an IEEE802.15.4-compliant radio transceiver with onboard 24 MHz crystal circuitries,
RF, and certified antenna or external antenna options.
o The low power module option has a capability of +8dBm output power at the antenna (see Figure
3-1).
o The high power module option has a capability of +18.5dBm output power at the antenna (see
Figure 3-2).
• Variety of interfaces are available such as UART, SPI, TIMER, ADC, Operational amperifier and GPIO.
• DFZM-E72xx contains single power supply (VCC).
3-2-2.CPU and Memory
The EM357 integrates the ARM® Cortex-M3 microprocessor. The ARM® Cortex-M3 is an advanced 32-bit
modified Harvard architecture processor that has separate internal program and data buses, but presents a unified
program and data address space to software. The word width is 32 bits for both the program and data sides. The
ARM® Cortex-M3 allows unaligned word and half-word data accesses to support efficiently-packed data
structures.
The ARM® Cortex-M3 clock speed is configurable to 6 , 12 , or 24 MHz. For normal operation 24 MHz is
preferred over 12 MHz due to improved performance for all applications and improved duty cycling for
applications using sleep modes. The 6 MHz operation can only be used when radio operations are not required
since the radio requires an accurate 12 MHz clock.
The ARM® Cortex-M3 in the EM357 has also been enhanced to support two separate memory protection levels.
Basic protection is available without using the MPU, but normal operation uses the MPU. The MPU allows for
protecting unimplemented areas of the memory map to prevent common software bugs from interfering with
software operation. The architecture could also allow for separation of the networking stack from the application
code using a fine granularity RAM protection module. Errant writes are captured and details are reported to the