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CC112X/CC1175
SWRU295C
Page 7 of 108
3
Microcontroller Interface
3.1
Configuration
In a typical system,
CC112X
will interface to an MCU. This MCU must be able to communicate with the
CC112X
over a 4-wire SPI interface to be able to:
Configure the
CC112X
Program
CC112X
into different modes (RX, TX, SLEEP, IDLE, etc)
Read and write buffered data (RX FIFO and TX FIFO)
Read status information
3.1.1
4-wire Serial Configuration and Data Interface
CC112X
is configured via a simple 4-wire SPI-compatible interface (SI, SO, SCLK, and CSn) where
CC112X
is the slave. This interface is also used to read and write buffered data. All transfers on the SPI
interface are done most significant bit first.
All transactions on the SPI interface start with a header byte containing a R/W
¯ bit, a burst access bit
(B), and a 6-bit address (A
5
- A
0
). A status byte is sent on the SO pin each time a header byte is
transmitted on the SI pin (see Section 3.1.2 for more details on the chip status byte).
The CSn pin must be kept low during transfers on the SPI bus. The timing for the address and data
transfers on the SPI interface is shown in Figure 3 with reference to Table 1.
0
B
A
5
A
4
A
3
A
2
A
1
A
0
D
W7
D
W6
D
W5
D
W4
D
W3
D
W2
D
W1
D
W0
X
X
S
7
t
sp
S
5
S
4
S
3
S
2
S
1
S
0
S
7
S
6
S
5
S
4
S
3
S
2
S
1
S
0
Hi Z
S
0
X
Hi Z
1
B
A
5
A
4
A
3
A
2
A
1
A
0
X
X
S
7
S
6
S
5
S
4
S
3
S
2
S
1
S
0
D
R7
D
R6
D
R5
D
R4
D
R3
D
R2
D
R1
D
R0
S
0
Hi Z
0
t
ch
t
cl
t
sd
t
hd
t
ns
SCLK
CSn
SI
SO
SI
SO
Write to Register
Read from Register
Hi Z
Figure 3: Configuration Registers Write and Read Operations