24LC01B-MT MicrochipTechnology, 24LC01B-MT Datasheet - Page 6

• Manufacturer Part Number: 24LC01B-MT
• Description: 1K/2KI2CSerialEEPROMsinISOMicromodules
• Manufacturer: MicrochipTechnology

24LC01B/02B Modules
6.0
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 6-1 for flow diagram.
FIGURE 6-1:
DS21222A-page 6
ACKNOWLEDGE POLLING
Initiate Write Cycle
Send Control Byte
Write Command
ACKNOWLEDGE POLLING
FLOW
with R/W = 0
Acknowledge
Condition to
Send Stop
(ACK = 0)?
Did Device
Send Start
Operation
Send
Next
YES
NO
7.0
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.
7.1
The 24LC01B/02B contains an address counter that
maintains the address of the last word accessed, inter-
nally incremented by one. Therefore, if the previous
access (either a read or write operation) was to address
n, the next current address read operation would
access data from address n + 1. Upon receipt of the
slave address with R/W bit set to one, the 24LC01B/
02B issues an acknowledge and transmits the 8-bit
data word. The master will not acknowledge the transfer
but does generate a stop condition and the 24LC01B/
02B discontinues transmission (Figure 7-1).
7.2
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
24LC01B/02B as part of a write operation. After the
word address is sent, the master generates a start con-
dition following the acknowledge. This terminates the
write operation, but not before the internal address
pointer is set. Then, the master issues the control byte
again but with the R/W bit set to a one. The 24LC01B/
02B will then issue an acknowledge and transmits the
8-bit data word. The master will not acknowledge the
transfer but does generate a stop condition and the
24LC01B/02B discontinues transmission (Figure 7-1).
7.3
Sequential reads are initiated in the same way as a ran-
dom read except that after the 24LC01B/02B transmits
the first data byte, the master issues an acknowledge
as opposed to a stop condition in a random read. This
directs the 24LC01B/02B to transmit the next sequen-
tially addressed 8-bit word (Figure 7-2).
To provide sequential reads the 24LC01B/02B contains
an internal address pointer which is incremented by
one at the completion of each operation. This address
pointer allows the entire memory contents to be serially
read during one operation.
7.4
The 24LC01B/02B employs a V
circuit which disables the internal erase/write logic if the
V
The SCL and SDA inputs have Schmitt trigger and filter
circuits which suppress noise spikes to assure proper
device operation even on a noisy bus.
CC
is below 1.5 volts at nominal conditions.
READ OPERATION
Current Address Read
Random Read
Sequential Read
Noise Protection
1997 Microchip Technology Inc.
CC
threshold detector