Register Access through SPI
R/W specifies the type of operation:
0 = Read
1 = Write
Thus, this bit is associated with the presence of information on MOSI (when writing) or MISO (when
reading).
Figure 4 and Figure 5 show write and read operations in a typical SPI transfer. In both cases, the SPI is a
slave. A received byte is considered internally on the eighth falling edge of SCLK. Consequently, the last
received bits, which do not form a complete byte, are lost.
NOTE
A low level applied to CONFB does not affect the configuration register
contents.
SEB
CONFB
SCLK
(Input)
MOSI
(Input)
MISO
(Output)
N1 N0 A4 A3 A2 A1 A0 R/W
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
Figure 4. Write Operation in Configuration Mode (N[1:0] = 01)
SEB
CONFB
SCLK
(Input)
MOSI
(Input)
MISO
(Output)
N1 N0 A4 A3 A2 A1 A0 R/W
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
Figure 5. Read Operation in Configuration Mode (N[1:0] = 01)
10.3 Configuration Switching
This feature allows for defining two different configurations using two different banks, and for switching
them automatically during wakeup when using a strobe oscillator, or by means of the strobe pin actuation
by the MCU.
MC33596 Data Sheet, Rev. 3
Freescale Semiconductor
11