
Data Sheet
49
Rev. 1.0, 2005-06-02
OctalLIU
TM
PEF 22508 E
Functional Description
Figure 12 and Figure 13 show the read and the write operation respectively. The start of a read or write operation
is marked by the falling edge of the chip select signal CS whereas the end of the operations is marked by the rising
edge of CS. Because of CS the SPI interface has no slave address.
The first bit of the serial data in (SDI) is 1 for a read operation and 0 for a write operation. The first four bits of
the 15-bit address are not valid for the OctalLIU
TM.
In read operation the OctalLIU
TM delivers the 8 bit wide content of the addressed register at the serial data out
(SDO).
In general SPI data are driven with the negative edge of the serial clock (SCLK) and sampled with the positive
edge of SCLK. Figure 50 shows the timing of the SPI interface and Table 57 the appropriate timing parameter
values.
Figure 12
SPI Read Operation
Figure 13
SPI Write Operation
3.5.3
Interrupt Interface
Special events in the OctalLIU
TM are indicated by means of an interrupt output INT, which requests the external
micro controller to read status information from the OctalLIU
TM, or to transfer data from/to the OctalLIUTM. The
electrical characteristics (open drain or push-pull) is programmed defined by the register bits IPC.IC(1:0), see IPC.
The OctalLIU
TM has a single interrupt output pin INT with programmable characteristics (open drain or push-pull,
defined by registers IPC) too.
Since only one INT request output is provided, the cause of an interrupt must be determined by the external micro
controller by reading the OctalLIU
TM’s interrupt status registers (GIS, ISR(1:4), ISR6 and ISR7). The interrupt on
pin INT and the interrupt status bits are reset by reading the interrupt status registers. The interrupt status registers
ISR are of type “clear on read“ (“rsc”).
The structure of the interrupt status registers is shown in Figure 14.
Octal_FALC_SPI_read
CS
SCLK
xx
x
A10
A0
D7
D0
11bit address
8bit data
SDI
dont care
highimpedance
SDO
Octal_FALC_SPI_write
CS
SCLK
xx
x
A10
A0 D7
D0
11 bit address
8bit data
SDI
highimpedance
SDO