EM4450

EM4550

Copyright

 2003, EM Microelectronic-Marin SA

9

www.emmicroelectronic.com

After reception of the command, the address, and the data, the EM4450/4550 will check the parity, the write protection

status, the Login status, and also if the available power from the RF field is sufficient. If all the conditions are satisfied, an

acknowledge pattern (ACK) will be issued afterward and the EEPROM writing process will start. At the end of programming,

the chip will send an Acknowledge pattern (ACK). If at least one of the checks fails, the chip will issue a no acknowledge

pattern (NAK) instead of ACK and return to the Standard Read Mode. The Transceiver will keep the RF field permanently

"ON" during the whole writing process time.

The Read After Write function (bit 17 of Control word) controls the mode of operation following a write operation. When

"ON" the latest written word will be read out and output next to the ACK pattern and two Listen Windows (LIW-LIW) even if

the word is read protected. When "OFF", the ACK is followed immediately by a LIW-LIW and FWR. The last written word is

not output.

If a request from the transceiver to return in receive mode (RM) is generated during the LIW, another word can be written in.

Otherwise, the EM4450/4550 will return in the Standard Read Mode.

Fig. 16

WORD n

LIW

ACK

LIW

LIW

FWR

output

input

ACK

t

wa

t

wee

TRANSCEIVER RF FIELD "ON"

WORD n

LIW

output

input

RM WRITE WORD ADDRESS

DATA

ACK LIW

ACK

t

wa

t

wee

TRANSCEIVER RF FIELD "ON"

Write 1 word

Write severalwords

RM WRITE WORD ADDRESS

DATA

RM WRITE WORD ADDRESS

DATA

WORD n

LIW

ACK LIW LIW Last Written LIW LIW

FWR

output

input

ACK

t

wa

t

wee

TRANSCEIVER RF FIELD "ON"

Read After Write function

RM WRITE WORD ADDRESS

DATA

WORD n

LIW

NACK

LIW

LIW

FWR

output

input

t

wa

TRANSCEIVER RF FIELD "ON"

Write not allowed or wrong transmission

RM WRITE WORD ADDRESS

DATA