Rf22, Controller interface, Serial peripheral interface (spi) – Rainbow Electronics RF22 User Manual
Page 8: Figure2. tx timing. figure3. rx timing, Figure4. spi timing, Table10. serial interface timing parameters, Sdi nsel sclk, Symbol parameter min (nsec) diagram t, Clock high time 40 t, Clock low time 40 t
RF22
Version: 0.1 Date: 12/23/2008
Tel: +86-755-82973805 Fax: +86-755-82973550 E-mail: [email protected] http://www.hoperf.com
8
TX Packet
XTAL Settling
Time
0T
L
L
P
L
A
C
LL
P
S
T
L
L
P
~1ms
P
M
A
R
A
P
E
R
P
P
U
P
M
A
R
A
P
Y
A
L
E
D
D
O
M
X
T
N
W
O
D
P
M
A
R
A
P
C
onf
ig
ur
abl
e 0~
70u
s, D
ef
aul
t=20u
s
45
us,
may be sk
ipe
d
C
onf
igur
ab
le
0~
31
0us,
Rec
ommen
ded 10
0us
6
us,
F
ixe
d
C
onf
ig
ur
abl
e 5~
20u
s, R
eco
mmende
d
5
us
1.5
B
it
s@D
R
RX Packet
XTAL Settling
Time
0T
LL
P
L
A
C
L
L
P
ST
L
L
P
~1ms
C
onfigur
able 0~70
us,
Default=20
us
45
us, ma
y be sk
ip
ed
Con
figura
ble 0
~
310u
s, Rec
ommended 100us
Figure2. TX Timing. Figure3. RX Timing
3. Controller Interface
3.1. Serial Peripheral Interface (SPI)
The RF22 communicates with the host MCU over a 3 wire SPI interface: SCLK, SDI, and nSEL. The host MCU can
also read data from internal registers on the SDO output pin. A SPI transaction is a 16-bit sequence which consists of a
Read-Write (R/W) select bit, followed by a 7-bit address field (ADDR), and an 8-bit data field (DATA), as demonstrated
in Figure 4. The 7-bit address field supports reading from or writing to one of the 128, 8-bit control registers. The R/W
select bit determines whether the SPI transaction is a write or read transaction. If R/W = 1, it signifies a WRITE
transaction, while R/W = 0 signifies a READ transaction. The contents (ADDR or DATA) are latched into the RF22
every eight clock cycles. The timing parameters for the SPI interface are shown in Table 10. The SCLK rate is flexible
with a maximum rate of 10 MHz.
Address
Data
RW
A5
A3
RW A7
A6
xx
xx
A4
D0
A2 A1 A0 D7 D6 D5 D4 D3 D2 D1
LSB
MSB
SDI
nSEL
SCLK
Figure4. SPI Timing
Table10. Serial Interface Timing Parameters
Symbol
Parameter
Min (nsec)
Diagram
t
CH
Clock high time
40
t
CL
Clock low time
40
t
DS
Data setup time
20
t
DH
Data hold time
20
t
DD
Output data delay time
20
t
EN
Output enable time
20
t
DE
Output disable time
50
t
SS
Select setup time
20
t
SH
Select hold time
50
t
SW
Select high period
80
SW
t
DE
t
SH
t
N
E
t
SS
t
DD
t
DH
t
DS
t
CH
t
CL
t
nSEL
SCLK
SDI
SDO