CC2400-RTR1 datasheet(45/84 Pages) TI

45 / 84 page

CC2400

SWRS042A

Page 45 of 83

35 Carrier Sense

The carrier sense signal is based on the

measured

RSSI

value

and

programmable threshold. The carrier-

sense function can be used to simplify the

implementation of a CSMA (Carrier Sense

Multiple Access) medium access protocol.

Carrier

sense

threshold

level

programmed

RSSI.RSSI_CS_THRES[5:0].

The

value of this register can be calculated in

the

same

way

described

for

RSSI.RSSI_VAL in the previous section,

except that the unit is 4 dB instead of 1

dB. The default level (0x3C) corresponds

to a threshold of –70 dBm. A threshold of

0x09 corresponds to –18 dBm, and a

threshold of 0x37 corresponds to –90

dBm.

The

carrier

sense

signal

can

multiplexed to the GIO1/GIO6 pin. The

CARRIER_SENSE_N signal is enabled by

setting

IOCFG.GIO1_CFG[5:0]

01010B (see Table 18).

36 Interfacing an External LNA or PA

CC2400 has two digital output pins, GIO1

and GIO6, which can be used to control

an external LNA or PA. The functionality of

these pins are controlled through the

IOCFG register.

The PA_EN, PA_EN_N, RX_PD, TX_PD

signals

can

multiplexed

the

GIO1/GIO6 pin and used for controlling

the PA / LNA and one or more T/R

switches.

These two pins can also be used as two

general control signals, see Table 18.

For further information on attaching a PA,

please see page 54.

37 General Purpose / Test Output Control Pins

The two digital output pins, GIO1 and

GIO6, can be used as two general control

signals

writing

IOCFG.GIO1_CFG[5:0]

and

IOCFG.GIO6_CFG[5:0].

GIO1_CFG = 61 sets the pin low, and

GIO1_CFG = 62 sets the pin high.

This feature can be used to save I/O pins

on the microcontroller when the other

functions associated with these pins are

not used.

These two pins can also be used as a test

pin to monitor a lot of internal signals. This

is summarized in Table 18.

GIO1_CFG /

GIO6_CFG

[decimal]

Signal

I/O

Description

Reserved

PA_EN

Active high PA enable signal

PA_EN_N

Active low PA enable signal

SYNC_RECEIVED

Set if a valid sync word has been received since last

time RX was turned on

PKT

Packet status signal See Figure 10, page 28.

Reserved

CC2400-RTR1 数据表(PDF) 45 Page - Texas Instruments

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