U3280M Datasheet, PDF (8/18 Pages) ATMEL Corporation – TRANSPONDER INTERFACE FOR MICROCONTROLLER

Write Operations
Acknowledge Polling
Write One Data Byte
Write Two Data Bytes
Write Control Byte Only
Write Control Bytes
The EEPROM allows for 8-bit and 16-bit write operations. A write access starts with the
START condition followed by writing a write control byte and one or two data bytes from
the master. It is completed with the STOP condition from the master after the acknowl-
edge cycle.
When the EEPROM receives the control byte, it loads the addressed memory cell into a
16-bit read/write buffer. The following data bytes overwrite the buffer. The internal
EEPROM programming cycle is started by a STOP condition after the first or second
data byte. During the programming cycle, the addressed EEPROM cells are cleared and
the contents of the buffer is written back to the EEPROM cells. The complete erase-
write cycle takes about 10 ms.
If the EEPROM is busy with an internal write cycle, all inputs are disabled and the
EEPROM will not acknowledge until the write cycle is finished. This can be used to
determine when the write cycle is complete. The master must perform acknowledge
polling by sending a START condition followed by the control byte. If the device is still
busy with the write cycle, it will not return an acknowledge and the master has to gener-
ate a STOP condition or perform further acknowledge polling sequences.
If the cycle is complete, the device returns an acknowledge and the master can proceed
with the next read or write cycle.
START
Control byte A Data byte 1 A STOP
START Control byte A Data byte 1 A Data byte 2 A STOP
START Control byte
A →acknowledge
A STOP
Write Low Byte First
MSB
LSB
A4
A3
A2
A1
A0
C1
C0
R/NW
Row address
0
1
0
Byte Order
LB(R)
HB(R)
Write High Byte First
MSB
LSB
A4
A3
A2
A1
A0
C1
C0
R/NW
Row address
1
0
0
Byte Order
HB(R)
LB(R)
HB: high byte; LB: low byte; R: row address
8 U3280M
4688B–RFID–12/04