R

EM4150

EM4350

Selective Read Mode cont.

The Selective Read mode command is followed by a single 32-bit word containing the new first and last addresses. Bits 0

to 7 correspond to the First Word Read and bits 8 to 15 correspond to the Last Word Read. Bits 16 to 31 have to be sent

but are not used in the chip. The parities must be sent according to the word organisation as described in fig.7. Note that

bit 31 is transmitted first.

To read the device Identification or the Serial Number, the Selective Read Command allows direct access to the Laser

programmed words. These words can also be addressed in the standard read mode by selecting the addresses

accordingly.

OUTPUT

WORD n

LIW

INPUT

RM Selective RD

ADDRESSES

LIW

FWR

LIW

ACK/NAK

LIW

Fig. 11

LW7 LW6 LW5 LW4 LW3 LW2 LW1 LW0 P1 FW7 FW6 FW5 FW4 FW3 FW2 FW1 FW0 P0 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 "0"

Addresses Bit Stream Format

First bit received

XX

XX

XX

XX

XX

XX

XX

XX

P3 XX

XX

XX

XX

XX

XX

XX

XX

P2

Fig. 12

Reset Command

The Reset Command will return from any mode to the Standard Read Mode. The next word out is the FWR.

OUTPUT

WORD n

LIW

INPUT

RM

RESET

LIW

FWR

LIW

LIW

ACK/NAK

Fig. 13

Login

The Login command is used to access protected memory areas. This command has to be used only once to perform

several password protected commands. The Power-On sequence and the Reset command will reset the password entry,

and a new Login command has to be received to perform further password protected operations.

Upon reception of a correct password, the EM4150 will respond with an acknowledge pattern (ACK) and then continue in

Standard Read Mode. If the Login is correct then password protected operations are allowed. If the password is incorrect, a

NAK pattern is issued and password protected operations will not be possible (refer to Write Word for password data

structure).

OUTPUT

WORD n

LIW

INPUT

RM

LOGIN

PASSWORD

LIW

FWR

LIW

LIW

ACK/NAK

Fig. 14

If bit 16 of the control word is disabled (Password Check ON/OFF), the Login is still mandatory to modify the Protection

Word, the Control Word, and the Password, but not to write in the EEPROM which is not write inhibited. In order to modify a

write inhibited word, the Protection word has to be modified first. The Read protected area always requires the Login to be

read. If the Write Protection Word is write protected, the write protection configuration is locked.

Copyright

6

www.emmicroelectronic.com