CC2420 Datasheet, PDF (32/92 Pages) List of Unclassifed Manufacturers – 2.4 GHz IEEE 802.15.4 / ZigBee-ready RF Transceiver

CC2420
CSn
SI
SO
ADDR
Status
ADDR
Status
-
-
ADDR_TXFIFO DATA_ADDR DATA_ADDR+1 DATA_ADDR+2
DATA_8MSB DATA_8LSB
Status
Status
Status
Status
Command
Strobe
Register
Read
TXFIFO
Write
Figure 11. Multiple SPI Access Example
14 Microcontroller Interface and Pin Description
When used in a typical system, CC2420 will
interface to a microcontroller. This
microcontroller must be able to:
• Program CC2420 into different modes,
read and write buffered data, and read
back status information via the 4-wire
SPI-bus configuration interface (SI, SO,
SCLK and CSn).
• Interface to the receive and transmit
FIFOs using the FIFO and FIFOP
status pins.
• Interface to the CCA pin for clear
channel assessment.
• Interface to the SFD pin for timing
information (particularly for beaconing
networks).
configuration interface (SI, SO, SCLK and
CSn). SO should be connected to an input
at the microcontroller. SI, SCLK and CSn
must be microcontroller outputs.
Preferably the microcontroller should have
a hardware SPI interface.
The microcontroller pins connected to SI,
SO and SCLK can be shared with other
SPI-interface devices. SO is a high
impedance output as long as CSn is not
activated (active low).
CSn should have an external pull-up
resistor or be set to a high level when the
voltage regulator is turned off in order to
prevent the input from floating. SI and
SCLK should be set to a defined level to
prevent the inputs from floating.
14.1 Configuration interface
A CC2420 to microcontroller interface
example is shown in Figure 12. The
microcontroller uses 4 I/O pins for the SPI
CC2420
FIFO
FIFOP
CCA
SFD
µC
GIO0
Interrupt
GIO1
Timer Capture
CSn
SI
SO
SCLK
GIO2
MOSI
MISO
SCLK
Figure 12. Microcontroller interface example
SWRS041B
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