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EM4450A5WW11E Datasheet(PDF) 8 Page - EM Microelectronic - MARIN SA |
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EM4450A5WW11E Datasheet(HTML) 8 Page - EM Microelectronic - MARIN SA |
8 / 16 page EM4450 EM4550 Copyright 2003, EM Microelectronic-Marin SA 8 www.emmicroelectronic.com 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. Write Password When a Write Password command is received, the chip next expects information on the actual valid password. The chip sends back an ACK pattern if the password is correct. Then the chip expects the new password consisting of 32 bits + parity bit to be stored in the EEPROM. The chip will respond with an ACK pattern for a correct reception of data upon reception of the new password, and then will send another acknowledge pattern (ACK) to announce that the data is stored in the EEPROM. The Read after Write function has no effect on this command. If the password is wrong or the transmission is faulty, the chip will : send a NAK pattern; return to the Standard Read Mode; and, the password will remain the same. (Refer to Write Word for password data structure). Fig. 14 Write Word The Write mode allows modification of the EEPROM contents word by word. To modify address 1 (Protection word) and address 2 (Control word), it is mandatory to first send a Login command in order to Log in (like in a computer). The new written values will take effect only after performing a Reset command. It is strongly recommended to check the result of modifying the contents of these addresses effecting the function of the chip. Address 0 (Password) cannot be modified with this command but can be changed with the Write Password command. Addresses 3 to 31 are programmable according to the defined protections. If the Password Check bit is off (bit 16 of control word) and the word is not write inhibited, the selected word can be freely modified without password. If the Password Check bit is on and the word is not write inhibited, the selected word can be modified with a previous Login. In any case, if the word is write inhibited, the protection word has to be changed before programming can occur. Write to Address Check Password bit (bit 16 / Control word) Write Inhibit (Protection word) Write Operation 0 X X Only with Write Password command 1 – 2 X OFF Login always required 1 – 2 X ON Write configuration LOCKED 3 – 31 OFF OFF Freely programmable 3 – 31 ON OFF Login required 3 – 31 X ON Change protection word first The Write Word command is followed by the address and data. The address consists of a 9 bit block containing 8 data bits and 1 even parity bit. Only 6 bits from the data section are used for the word addressing, and the first three bits sent must be "0". The data consists of 4 times 9 bit blocks, each block consisting of 8 data bits and 1 associated even parity bit and one additional block consisting of 8 column parity bits and "0" as stop bit (Refer to fig. 7) D31 D30 D29 D28 D27 D26 D25 D24 P3 D23 D22 D21 D20 D19 D18 D17 D16 P2 D15 D14 D13 D12 .......................... D02 D01 D00 P0 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 "0" 0 0 A5 A4 A3 A2 A1 A0 Padd Address Data First bit received Note : A5 in write mode always "0" (addresses Laser ROM) Fig. 15 WORD n LIW RM WRITE PW ACTUAL PW ACK LIW LIW FWR t pp output input ACK LIW RM NEW PW ACK t wa t wee TRANSCEIVER RF FIELD "ON" |
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