Texas Instruments CC2500 User Manual

CC2500
S
WRS040
C
Page
52
of
89
29
General Purpose
/ Test Output Control Pins
The three digital output pins
GDO0
,
GDO1
and
GDO2
are general control pins configured with
IOCFG0.GDO0_CFG
,
IOCFG1.
GDO1
_CFG
and
IOCFG2.GDO2
_CFG
respectively.
Table
33
shows the different signals that can be
monitored on the
GDO
pins.
These signals can
be used as inputs
to the MCU.
GDO1
is the
same pin as the
SO
pin on the SPI interface,
thus the output prog
rammed 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 135
-
141 kHz
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 by writing to
IOCFG0.GDO0_CFG
.
An on
-
chip anal
og temperature sensor is
enabled by writing the value 128 (0x80) to the
IOCFG0.GDO0_CFG
register. The
voltage on
the
GDO0
pin is then proportional to
temperature. See Section
4.7
on pa
ge
14
for
temperature sensor specifications.
If
the
IOCFGx.GDO0_CFG
setting i
s less than
0x20
and
IOCFGx_GDOx_INV
is
0 (1),
t
he
GDO0
and
GDO
2
pins
will be hardwired to 0
(1)
and
the
GDO1
pin
will be
hardwired
to 1 (0)
in
the
SLEEP state
.
These signals will be
hardwired until the
CHIP_RDYn
signal goes
low.
If
the
IOCFGx.GDO0_CFG
setting i
s 0x20 or
higher the
GDO
pins will work as programmed
al
so in SLEEP state. As an example,
GDO1
is
high impedance in all states if
IOCFG1.GDO0_CFG
=
0x2E.

Texas Instruments CC2500 Specifications

General

Brand	Texas Instruments
Model	CC2500
Category	Transceiver
Language	English