User`s manual

Configuration and Operation
Operation
User’s Manual M9328MX1ADS - Rev 2
MOTOROLA Configuration and Operation 21
Table 2-11 and Figure 2-10 shows the interface to software controlled periph-
eral enables. Peripherals can be enable or disable by programming the I/O
expander. This depends on the state of the associated enable switch (S1) which
can override software control. The write slave address is 0x44 and the read
address is 0x45.
The PCF8575 consists of a 16-bit quasi-bidirectional port and an I
2
C-bus inter-
face. On power up all pins are configured as inputs. A non power up reset has
no effect on the PCF8575 which communicates with the MC9328MX1 through
the I
2
C interface. For the details on the operation of PCF8575, please refer to
its data sheet. The data sheet is available on the web:
http://www.semiconductors.philips.com
Figure 2-9 Keypads and I/O Expander Interface
PCF8575
I
2
CI
2
C
INTSIM_PD
A[0..2]
I/O
Keypads
M
C9328MX1
I
2
C Slave Address 0x48
Address
assignment
resistors
U33