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CC11x1-Q1
SWRS076B – 11-07-22-013 - APRIL 2009 – REVISED APRIL 2010
3.7
Microcontroller Interface and Pin Configuration
In a typical system, CC11x1-Q1 interfaces to a microcontroller. This microcontroller must be able to:
•
Program CC11x1-Q1 into different modes
•
Read and write buffered data
•
Read back status information via the 4-wire SPI-bus configuration interface (SI, SO, SCLK and CS).
3.7.1 Configuration Interface
The microcontroller uses four I/O pins for the SPI configuration interface (SI, SO, SCLK and CS). The SPI
is described in
Section
3.7.2 General Control and Status Pins
The CC11x1-Q1 has two dedicated configurable pins (GDO0 and GDO2) 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
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 becomes a generic pin. When CS is
low, the pin functions 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
With default PTEST register setting (0x7F) the temperature sensor output is available only when the
frequency synthesizer is enabled (e.g., the MANCAL, FSTXON, RX, 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).
3.7.3 Optional Radio-Control Feature
The CC11x1-Q1 has an optional way of controlling the radio by reusing SI, SCLK, and CS from the SPI
interface. This allows simple three-pin control of the major states of the radio: SLEEP, IDLE, RX, and TX.
This optional functionality is enabled with the MCSM0.PIN_CTRL_EN configuration bit.
State changes are commanded as follows: When CS is high, the SI and SCLK is set to the desired state
according to
Table
generated internally according to the pin configuration. It is only possible to change state with this
functionality. That means that, for instance, RX is not restarted if SI and SCLK are set to RX and CS
toggles. When CS is low, the SI and SCLK has normal SPI functionality.
All pin control command strobes are executed immediately, except the SPWD strobe, which is delayed
until CS goes high.
CS
1
↓
↓
↓
↓
0
28
Detailed Description
3.6.
Section 3.25
for more details on the signals that can be programmed. GDO1
Section
2.12.
3-4. When CS goes low, the state of SI and SCLK is latched and a command strobe is
Table 3-4. Optional Pin Control Coding
SCLK
SI
X
X
Chip unaffected by SCLK/SI
0
0
Generates SPWD strobe
0
1
Generates STX strobe
1
0
Generates SIDLE strobe
1
1
Generates SRX strobe
SPI mode
SPI mode
SPI mode (wakes up into IDLE if in SLEEP/XOFF)
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