Harman Kardon AVR 146, Service Manual

Page: 154 / 172

M24C64, M24C32
Page Write
The Page Write mode allows up to 32 bytes to be
written in a single Write cycle, provided that they
are all located in the same ’row’ in the memory:
that is, the most significant memory address bits
(b12-b5 for M24C64, and b11-b5 for M24C32) are
the same. If more bytes are sent than will fit up to
the end of the row, a condition known as ‘roll-over’
occurs. This should be avoided, as data starts to
become overwritten in an implementation depen-
dent way. The bus master sends from 1 to 32 bytes of data,
each of which is acknowledged by the device if
Write Control (WC) is Low. If Write Control (WC) is
High, the contents of the addressed memory loca-
tion are not modified, and each data byte is fol-
lowed by a NoAck. After each byte is transferred,
the internal byte address counter (the 5 least sig-
nificant address bits only) is incremented. The
transfer is terminated by the bus master generat-
ing a Stop condition.
Figure 8. Write Mode Sequences with WC=0 (data write enabled)
STOP
START
BYTE WRITE DEV SEL BYTE ADDR BYTE ADDR DATA IN
WC
START
PAGE WRITE DEV SEL BYTE ADDR BYTE ADDR DATA IN 1
WC
DATA IN 2
AI01106C
PAGE WRITE
(cont'd)
WC (cont'd)
STOP
DATA IN N
ACK
R/W
ACK ACK ACK
ACK ACK ACK ACK
R/W
ACK ACK
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AVR146
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