
MRF89XA
2.11.1 SPI CONFIG
Write Register - To write a value into a Configuration
register, the timing diagram illustrated in Figure 2-12
should be followed by the host microcontroller. The
new value of the register is effective from the rising
edge of CSCON.
FIGURE 2-12:
WRITE REGISTER SEQUENCE
Note:
When writing more than one register suc-
cessively, it is not compulsory to toggle
CSCON back high between two write
sequences. The bytes are alternatively
considered as address and value. In this
instance, all new values will become
effective on rising edge of CSCON.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
CSCON (In)
SCK (In)
New value at
address A1
SDI (In)
start
rw
A(4)
A(3)
A(2)
A(1) A(0)
stop
D(7)
D(6)
D(5)
D(4)
D(3)
D(2)
D(1)
D(0)
Address = A1
Current value at
address A1*
SDO (Out)
HZ
x
x
x
x
x
x
x
x
D(7)
D(6)
D(5)
D(4)
D(3)
D(2)
D(1)
D(0)
HZ
(input)
* when writing the new value at address A1, the current content of A1 can be read by the μC.
(In)/(Out) refers to MRF89XA side
(input)
Read Register - To read the value of a Configuration
register, the timing diagram illustrated in Figure 2-13
should be followed by the host microcontroller.
FIGURE 2-13:
READ REGISTER SEQUENCE
Note:
When reading more than one register suc-
cessively, it is not compulsory to toggle
CSCON back high between two read
sequences. The bytes are alternatively
considered as address and value.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
CSCON (In)
SCK (In)
SDI(In)
start
rw
A(4)
A(3)
A(2)
A(1)
A(0)
stop
xx
xx
x
x
xx
Address = A1
Current value at
address A1
SDO (Out)
HZ
(input)
x
x
x
x
x
x
x
x
D(7)
D(6)
D(5)
D(4)
D(3)
D(2)
D(1)
D(0)
HZ
(input)
DS70622C-page 24
Preliminary
? 2010–2011 Microchip Technology Inc.