CC2420
SWRS041B Page 28 of 89
0
0
A5
A4
A3
A2
A0
A1
D
W
15 D
W
14 D
W
13 D
W
12 D
W
11 D
W
10 D
W
9
D
W
8
D
W
7
D
W
6
D
W
5
D
W
4
D
W
3
D
W
2
D
W
1
D
W
0
S7
S6
S5
S4
S3
S2
S0
S1
0
1
A5
A4
A3
A2
A0
A1
D
R
15
D
R
14 D
R
13 D
R
12 D
R
11 D
R
10
D
R
9
D
R
8
D
R
7
D
R
6
D
R
5
D
R
4
D
R
3
D
R
2
D
R
1
D
R
0
S7
S6
S5
S4
S3
S2
S0
S1
Read from register / RXFIFO:
Write to register / RXFIFO:
X
X
X
X
X
D
R
15
SCLK
CSn
SI
SO
SI
SO
t
sp
t
ch
t
sd
t
hd
t
ns
t
cl
1
A6
A5
A4
A3
A2
A0
A1
B1
B0
0
X
X
X
X
X
D
W
7
D
W
6
D
W
5
D
W
4
D
W
3
D
W
2
D
W
1
D
W
0
S7
S6
S5
S4
S3
S2
S0
S1
1
A6
A5
A4
A3
A2
A0
A1
D
R
7
D
R
6
D
R
5
D
R
4
D
R
3
D
R
2
D
R
1
D
R
0
S7
S6
S5
S4
S3
S2
S0
S1
Read one byte from RAM: (multiple reads also possible)
Read and write one byte to RAM: (multiple read / writes also possible)
X
X
X
X
X
D
R
7
B1
B0
1
X
X
X
X
X
X
X
SI
SO
SI
SO
D
R
7
D
R
6
D
R
5
D
R
4
D
R
3
D
R
2
D
R
1
D
R
0
D
R
7
0
0
A5
A4
A3
A2
A0
A1
D
W
7
D
W
6
D
W
5
D
W
4
D
W
3
D
W
2
D
W
1
D
W
0
D
W
7
D
W
6
D
W
5
D
W
4
D
W
3
D
W
2
D
W
1
D
W
0
S7
S6
S5
S4
S3
S2
S0
S1
Write to TXFIFO:
X
X
X
SI
SO
S7
S6
S5
S4
S3
S2
S0
S1
S7
S6
S5
S4
S3
S2
S0
S1
S7
Figure 9. SPI timing diagram
Parameter
Symbol
Min
Max
Units
Conditions
SCLK
, clock
frequency
F
SCLK
10
MHz
SCLK
low
pulse
duration
t
cl
25
ns
The minimum time
SCLK
must be low.
SCLK
high
pulse
duration
t
ch
25
ns
The minimum time
SCLK
must be high.
CSn
setup
time
t
sp
25
ns
The minimum time
CSn
must be low before the first
positive
edge of
SCLK
.
CSn
hold time
t
ns
25
ns
The minimum time
CSn
must be held low after the
last
negative
edge of
SCLK
.
SI
setup time
t
sd
25
ns
The minimum time data on
SI
must be ready
before the
positive
edge of
SCLK
.
SI
hold time
t
hd
25
ns
The minimum time data must be held at
SI
, after
the
positive
edge of
SCLK
.
Rise time
t
rise
100
ns
The maximum rise time for
SCLK
and
CSn
Fall time
t
fall
100
ns
The maximum fall time for
SCLK
and
CSn
Note: The set-up- and hold-times refer to 50% of VDD.
Table 4. SPI timing specification
13.3 Status
byte
During transfer of the register access byte,
command strobes, the first RAM address
byte and data transfer to the TXFIFO, the
CC2420
status byte is returned on the
SO
pin. The status byte contains 6 status bits
which are described in Table 5.
Issuing a
SNOP
(no operation) command
strobe may be used to read the status
byte. It may also be read during access to
chip functions such as register or FIFO
access.