ASAHI KASEI
[AK6004A/08A]
READ Operations
There are three basic read operations: current address read, random read, and sequential read.
Read operations are initiated in the same manner as write operations, with the exception that the
R/W bit of the slave address is set to a one.
It is noted that the ninth clock cycle of the read operation is not a "don't care". To terminate a read
operation, the master must hold SDA HIGH during the ninth clock cycle and then issue a stop
condition.
CURRENT ADDRESS READ
Internally the AK6004A/08A contains an address counter that maintains the address of the last word
accessed, incremented by one. Therefore, if the last access (either a read or write) was to address
n, the next read operation would access data from address n+1.
Upon receipt of the slave address with R/W bit set to one, the AK6004A/08A issues an acknowledge
and transmits the eight bit word. The master will not acknowledge the transfer but generate a stop
condition, and therefore the AK6004A/08A discontinues transmission.
S
T
A
R
T
S
T
O
P
P
A
C
K
Bus Activity:
Master
SLAVE
ADDRESS
DATA
SDA LINE S
Bus Activity:
AK6004A/08A
CURRENT ADDRESS READ
RANDOM READ
Random read operations allow the master to access any memory location in a random manner.
Prior to issuing the slave address with the R/W bit set to one, the master must first perform a
"dummy" write operation.
The master issues the start condition, slave address and then the word address it is to read. After
the word address acknowledge, the master immediately reissues the start condition and the slave
address with the R/W bit set to one. This will be followed by an acknowledge from the
AK6004A/08A and then by the eight bit word. The master will not acknowledge the transfer but
generate the stop condition, and therefore the AK6004A/08A discontinues transmission.
S
T
A
R
T
S
T
A
R
T
S
※
Bus Activity:
Master
SLAVE
ADDRESS
WORD
ADDRESS(n)
SLAVE
ADDRESS
DATA(n)
S
T
O
P
P
SDA LINE S
Bus Activity:
AK6004A/08A
A
C
K
A7 - A0
A
C
K
A
C
K
※:
S2, S1, A8 (AK6004A) or A10, A9, A8 (AK6008A)
RANDOM READ
DAI01E-02
- 9 -
2002/11
AKM [ ASAHI KASEI MICROSYSTEMS ]
