CC2550_13 Datasheet, PDF (18/61 Pages) Texas Instruments – Low-Cost Low-Power 2.4 GHz RF Transmitter

CC2550
The access to the PATABLE is either single
byte or burst access depending on the burst
bit. When using burst access the index counter
will count up; when reaching 7 the counter will
restart at 0. The R/W bit controls whether the
access is a write access (R/W=0) or a read
access (R/W=1).
If one byte is written to the PATABLE and this
value is to be read out then CSn must be set
high before the read access in order to set the
index counter back to zero.
Note that the content of the PATABLE is lost
when entering the SLEEP state.
See Section 21 on page 30 for output power
programming details.
Figure 8: Register Access Types
11 Microcontroller Interface and Pin Configuration
In a typical system, CC2550 will interface to a
microcontroller. This microcontroller must be
able to:
• Program CC2550 into different modes
• Write buffered data
• Read back status information via the 4-wire
SPI-bus configuration interface (SI, SO,
SCLK and CSn)
11.1 Configuration Interface
The microcontroller uses four I/O pins for the
SPI configuration interface (SI, SO, SCLK and
CSn). The SPI is described in Section 14 on
page 14.
11.2 General Control and Status Pins
The CC2550 has one dedicated configurable
pin (GDO0) and one shared pin (GDO1) that can
output internal status information useful for
control software. These pins can be used to
generate interrupts on the MCU. See Section
25 page 33 for more details of the signals that
can be programmed. GDO1 is shared with the
SO pin in the SPI interface. The default setting
for GDO1/SO is 3-state output. By selecting
any other of the programming options the
GDO1/SO pin will become a generic pin. When
CSn is low, the pin will always function as a
normal SO pin.
In the synchronous and asynchronous serial
modes, the GDO0 pin is used as a serial TX
data input pin while in transmit mode.
The GDO0 pin can also be used for an on-chip
analog temperature sensor. By measuring the
voltage on the GDO0 pin with an external ADC,
the temperature can be calculated.
Specifications for the temperature sensor are
found in Section 4.5 on page 8.
With default PTEST register setting (0x7F) the
temperature sensor output is only available
when the frequency synthesizer is enabled
(e.g. the MANCAL, FSTXON and TX states).
It is necessary to write 0xBF to the PTEST
register to use the analog temperature sensor
in the IDLE state. Before leaving the IDLE
state, the PTEST register should be restored to
its default value (0x7F).
SWRS039B
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