CAT1021, CAT1022, CAT1023
ACKNOWLEDGE
WRITE OPERATIONS
After a successful data transfer, each receiving
device is required to generate an acknowledge. The
acknowledging device pulls down the SDA line
during the ninth clock cycle, signaling that it received
the 8 bits of data.
Byte Write
In the Byte Write mode, the Master device sends the
START condition and the slave address information
(with the R/W bit set to zero) to the Slave device. After
¯¯
the Slave generates an acknowledge, the Master sends
a 8-bit address that is to be written into the address
pointers of the device. After receiving another acknow-
ledge from the Slave, the Master device transmits the
data to be written into the addressed memory location.
The device acknowledges once more and the Master
generates the STOP condition. At this time, the device
begins an internal programming cycle to non-volatile
memory. While the cycle is in progress, the device will
not respond to any request from the Master device.
All devices respond with an acknowledge after
receiving a START condition and its slave address.
If the device has been selected along with a write
operation, it responds with an acknowledge after
receiving each 8-bit byte.
When a device begins a READ mode it transmits 8
bits of data, releases the SDA line and monitors the
line for an acknowledge. Once it receives this
acknowledge, the device will continue to transmit
data. If no acknowledge is sent by the Master, the
device terminates data transmission and waits for a
STOP condition.
Figure 5. Start/Stop Timing
SDA
SCL
START BIT
STOP BIT
Figure 6. Acknowledge Timing
SCL FROM
MASTER
1
8
9
DATA OUTPUT
FROM TRANSMITTER
DATA OUTPUT
FROM RECEIVER
START
ACKNOWLEDGE
Figure 7: Slave Address Bits
Default Configuration
1
0
1
0
0
0
0
R/W
Doc. No. 3009 Rev. L
10
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CATALYST [ CATALYST SEMICONDUCTOR ]
