NXP Semiconductors freescale semiconductor MC13211, Reference Manual

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MC1321x Introduction
MC1321x Reference Manual, Rev. 1.6
1-12 Freescale Semiconductor
transmitted. In both modes, a two-byte FCS is calculated in hardware from the payload data and appended
to the packet. This done without intervention from the user.
1.7.6 Radio Usage
The MC1321x RF analog interface has been designed to provide maximum flexibility as well as low
external part count and cost. An optional on-chip transmit/receive (T/R) switch with the center tap bias
switch (CT_Bias) output can be used for a simple single antenna interface with an external balun.
Alternately, separate full differential RFIN and PAO outputs can be utilized for separate RX and TX
antennas or external LNA and PA designs.
Figure 1-6 shows a single antenna configuration in which the MC1321x internal T/R switch is used. The
balun converts the single-ended antenna to differential signals that interface to the RFIN_x (PAO_x) pins
of the radio. The CT_bias pin provides the proper bias point to the balun depending on operation, that is,
CT_bias is at VDDA voltage for transmit and is at ground for receive. The internal T/R switch enables the
signal to an onboard LNA for receive and enables the onboard PAs for transmit.
Use of the RF interface is described in detail in Section 3.10, “Transceiver RF Configurations and External
Connections” .
Figure 1-6. Using the MC1321x with the Onboard T/R Switch
1.8 MCU Overview
The MC1321x MCU is a member of the Freescale family of HCS08 microcontrollers which contains new
instructions to implement rapid debugging and development and still be fully compatible with all legacy
code written for the M68HC08 family. The MCU consists of the HCS08 core plus memory and peripheral
modules. The maximum clock speed of the HCS08 CPU is 40 MHz and the maximum MCU bus rate is
20 MHz (half the CPU clock frequency). The MCU is an excellent low voltage, low power device suitable
to 802.15.4 Standard and ZigBee specification.
The functional options available in the MC1321x family of devices vary only in the memory
configurations as detailed in
Table 1-1 . All peripheral modules and CPU functionality are similar across
the MC1321x family.
Balun
Bypass
RFIN_P (PAO_P)
RFIN_M (PAO_M)
CT_Bias
PAO_P
PAO_M
MC1321x
L1