24LC32A-MT MicrochipTechnology, 24LC32A-MT Datasheet - Page 8

• Manufacturer Part Number: 24LC32A-MT
• Description: 32KI2CSerialEEPROMinISOMicromodule
• Manufacturer: MicrochipTechnology

24LC32A MODULE
7.0
Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput). Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle. ACK polling can
be initiated immediately. This involves the master send-
ing a start condition followed by the control byte for a
write command (R/W = 0). If the device is still busy with
the write cycle, then no ACK will be returned. If the
cycle is complete, then the device will return the ACK
and the master can then proceed with the next read or
write command. See Figure 7-1 for flow diagram.
FIGURE 7-1:
FIGURE 8-1:
DS21225A-page 8
ACKNOWLEDGE POLLING
Initiate Write Cycle
Send Control Byte
Write Command
with R/W = 0
Condition to
Acknowledge
Send Stop
SDA LINE
Send Start
BUS ACTIVITY
MASTER
BUS ACTIVITY
Did Device
(ACK = 0)?
Operation
ACKNOWLEDGE POLLING
FLOW
CURRENT ADDRESS READ
Send
Next
YES
S
T
A
R
T
S
NO
1
0
CONTROL BYTE
1
0
0 0 0
1
8.0
Read operations are initiated in the same way as write
operations with the exception that the R/W bit of the
slave address is set to one. There are three basic types
of read operations: current address read, random read,
and sequential read.
8.1
The 24LC32A contains an address counter that main-
tains the address of the last word accessed, internally
incremented by one. Therefore, if the previous access
(either a read or write operation) was to address n (n is
any legal address), the next current address read oper-
ation would access data from address n + 1. Upon
receipt of the slave address with R/W bit set to one, the
24LC32A issues an acknowledge and transmits the
eight bit data word. The master will not acknowledge
the transfer but does generate a stop condition and the
24LC32A discontinues transmission (see Figure 8-1).
8.2
Random read operations allow the master to access
any memory location in a random manner. To perform
this type of read operation, first the word address must
be set. This is done by sending the word address to the
24LC32A as part of a write operation (R/W bit set to 0).
After the word address is sent, the master generates a
start condition following the acknowledge. This termi-
nates the write operation, but not before the internal
address pointer is set. Then the master issues the con-
trol byte again but with the R/W bit set to a one. The
24LC32A will then issue an acknowledge and transmit
the eight bit data word. The master will not acknowl-
edge the transfer but does generate a stop condition
which causes the 24LC32A to discontinue transmis-
sion (see Figure 8-2).
A
C
K
READ OPERATION
Current Address Read
Random Read
DATA BYTE
1997 Microchip Technology Inc.
N
O
A
C
K
S
T
O
P
P