1194 datasheet(30/50 Pages) TI

30 / 50 page

CC2550

Preliminary Data Sheet (rev. 1.1)

SWRS039

Page 30 of 51

The

passive

matching/filtering

network

connected to

CC2550 should have the following

differential impedance as seen from the RF-

port (RF_P and RF_N) towards the antenna:

Zout = 80 + j74 Ω

31 General Purpose / Test Output Control Pins

The two digital output pins GDO0 and GDO1 are

general control pins. Their functions are

programmed by IOCFG0.GDO0_CFG

and

IOCFG1.GDO1_CFG respectively. Table 23

shows the different signals that can be

monitored on the GDO pins. These signals can

be used as an interrupt to the MCU. GDO1 is

the same pin as the SO pin on the SPI

interface, thus the output programmed on this

pin will only be valid when CSn is high. The

default value for GDO1 is 3-stated, which is

useful when the SPI interface is shared with

other devices.

The default value for GDO0 is a 125kHz-

146kHz clock output (XOSC frequency divided

by 192). Since the XOSC is turned on at

power-on-reset, this can be used to clock the

MCU in systems with only one crystal. When

the MCU is up and running, it can change the

clock

frequency

writing

IOCFG0.GDO0_CFG. This will not produce

any clock glitches.

An on-chip analog temperature sensor is

enabled by writing the value 128 (0x80h) to the

IOCFG0.GDO0_CFG register. The voltage on

the

GDO0

then

proportional

temperature. See section 9 on page 8 for

temperature sensor specifications.

1194 Datasheet(PDF) 30 Page - Texas Instruments

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