1997 Apr 02 8
Philips Semiconductors Product specification
128 × 8-bit EEPROM with I
2
C-bus interface
PCA8581; PCA8581C
To transmit eight bytes in sequential order, begin with the lowest address bits 0 0 0. The data is written after a stop is
detected. The data is only written if complete bytes have been received and acknowledged. Writing takes a time t
WR
(6 to 10 ms) during which the device will not respond to its slave address. Note that to write the next row, a new write
operation is required (start, slave address, row address, data and stop).
An unlimited number of data bytes can be read in one operation. The address is automatically incremented. If a read
without setting the word address is performed after a write operation, the address pointer may point at a byte in the row
after the previously written row. This occurs if, during writing, the three lowest address bits (column) rolled over.
Fig.9 Master reads after setting word address (WRITE word address; READ data).
handbook, full pagewidth
S 0ASLAVE ADDRESS WORD ADDRESS A ASLAVE ADDRESS
acknowledgement
from slave
acknowledgement
from slave
acknowledgement
from slave
R/W
X
don't
care
acknowledgement
from master
ADATA
auto increment
memory word address
MLB891
P
no acknowledgement
from master
1DATA
auto increment
memory word address
last byte
R/W
S1
n bytes
at this moment master -
transmitter becomes
master - receiver and
PCA8581(C) slave - receiver
becomes slave - transmitter
Fig.10 Master reads slave immediately after first byte (READ mode).
handbook, full pagewidth
S
1A
SLAVE ADDRESS DATA
A1DATA
acknowledgement
from slave
acknowledgement
from slave
acknowledgement
from slave
R/W
auto increment
word address
MBD824
auto increment
word address
n bytes last bytes
P
