
2001 Oct 02
20
Philips Semiconductors
Product specication
Universal LCD driver for low multiplex rates
PCF8576
After acknowledgement, one or more command bytes (m)
follow which define the status of the addressed PCF8576s.
The last command byte is tagged with a cleared most
significant bit, the continuation bit C. The command bytes
are also acknowledged by all addressed PCF8576s on the
bus.
After the last command byte, a series of display data bytes
(n) may follow. These display bytes are stored in the
display RAM at the address specified by the data pointer
and the subaddress counter. Both data pointer and
subaddress counter are automatically updated and the
data is directed to the intended PCF8576 device. The
acknowledgement after each byte is made only by the (A0,
A1 and A2) addressed PCF8576. After the last display
byte, the I2C-bus master issues a STOP condition (P).
7.8
Command decoder
The command decoder identifies command bytes that
arrive on the I2C-bus. All available commands carry a
continuation bit C in their most significant bit position
(Fig.17). When this bit is set, it indicates that the next byte
of the transfer to arrive will also represent a command. If
this bit is reset, it indicates the last command byte of the
transfer. Further bytes will be regarded as display data.
The five commands available to the PCF8576 are defined
in Table 4.
Fig.12 Bit transfer.
MBA607
data line
stable;
data valid
change
of data
allowed
SDA
SCL
Fig.13 Definition of START and STOP conditions.
handbook, full pagewidth
MBC622
SDA
SCL
P
STOP condition
SDA
SCL
S
START condition