PCF8579 Philips Semiconductors, PCF8579 Datasheet - Page 16

• Manufacturer Part Number: PCF8579
• Description: LCD column driver for dot matrix graphic displays
• Manufacturer: Philips Semiconductors

Philips Semiconductors
8
Two 7-bit slave addresses (0111100 and 0111101) are
reserved for both the PCF8578 and PCF8579. The least
significant bit of the slave address is set by connecting
input SA0 to either logic 0 (V
Therefore, two types of PCF8578 or PCF8579 can be
distinguished on the same I
1. One PCF8578 to operate with up to 32 PCF8579s on
2. The use of two types of LCD multiplex schemes on the
In most applications the PCF8578 will have the same slave
address as the PCF8579.
The I
All communications are initiated with a start condition (S)
from the I
slave address and read/write bit. All devices with this slave
address acknowledge in parallel. All other devices ignore
the bus transfer.
In WRITE mode (indicated by setting the read/write bit
LOW) one or more commands follow the slave address
acknowlegement. The commands are also acknowledged
by all addressed devices on the bus.
The last command must clear the continuation bit C. After
the last command a series of data bytes may follow.
The acknowlegement after each byte is made only by the
(A0, A1, A2 and A3) addressed PCF8579 or PCF8578
with its implicit subaddress 0. After the last data byte has
been acknowledged, the I
condition (P).
1997 Apr 01
LCD column driver for dot matrix graphic
displays
the same I
same I
I
2
2
C-BUS PROTOCOL
C-bus protocol is shown in Fig.11.
2
C-bus master, which is followed by the desired
2
C-bus.
2
C-bus for very large applications.
2
C-bus master issues a stop
2
C-bus which allows:
SS
) or logic 1 (V
DD
).
16
In READ mode, indicated by setting the read/write bit
HIGH, data bytes may be read from the RAM following the
slave address acknowlegement. After this
acknowlegement the master transmitter becomes a
master receiver and the PCF8579 becomes a slave
transmitter. The master receiver must acknowledge the
reception of each byte in turn. The master receiver must
signal an end of data to the slave transmitter, by not
generating an acknowledge on the last byte clocked out of
the slave. The slave transmitter then leaves the data line
HIGH, enabling the master to generate a stop
condition (P).
Display bytes are written into, or read from, the RAM at the
address specified by the data pointer and subaddress
counter. Both the data pointer and subaddress counter are
automatically incremented, enabling a stream of data to be
transferred either to, or from, the intended devices.
In multiple device applications, the hardware subaddress
pins of the PCF8579s (A0 to A3) are connected to V
V
If two or more devices share the same slave address, then
each device must be allocated a unique hardware
subaddress.
DD
to represent the desired hardware subaddress code.
Product specification
PCF8579
SS
or