SAP5SD-B-G1-R datasheet(55/67 Pages) RENESAS

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SAP51 / SAP5S Datasheet

January 28, 2016

5.20. Write Protection of ID_Code_Extension_1

The ID_Code_Extension_1 register of the SAP5 can either be manufacturer configurable or user configurable. As

soon as the Lock_EE_PRG flag is set, access to the ID_Code_Extension_1 is handled as follows:

• If the flag Inhibit_Write_ID1 is set (‘1’) in the Firmware Area of the EEPROM, ID_Code_Extension_1 is

manufacturer configurable (refer to Table 4.2).

• In this case, the slave response to a Read_ID_Code_1 (RID1) request is constructed out of the data stored

on the internal EEPROM address 2 in User Area of the EEPROM.

• It does not matter which data is stored in the ID_Code_Extension_1 register in EEPROM address 1 in the

User Area. The SAP5 will always respond with the protected manufacturer programmed value.

• There is one exception to this principle. If the SAP5 is operated in Extended Address Mode, bit 3 of the

returned slave response is taken from the EEPROM address 1 register in the User Area. This is because

bit 3 functions as the A/B Slave selector bit in this case and must remain user configurable.

• To ensure consistency of the ID_Code_Extension_1 stored in the data image of Master as well as in the

EEPROM of the slave, the SAP5 will not process a Write_Extended_ID_Code_1 request if the data sent

does not match the data that is stored in the protected part of the ID_Code_Extension_1 register. It will

neither access the EEPROM nor send a slave response in this case.

• Note: As defined in the AS-Interface Complete Specification, a modification of the A/B Slave selector bit

must be performed bit selective. That means the AS-i master must read the ID_Code_Extension_1 first,

modify bit 3, and send the new 4-bit word that consists of the modified bit 3 and the unmodified bits 2 to 0

back to the slave.

• If the Inhibit_Write_ID1 flag is not set (‘0’), ID_Code_Extension_1 is completely user configurable. The data

to construct the slave response to a Read_ID_Code_1 request is completely taken from the

ID_Code_Extension_1 register on EEPROM address 1 in the User Area.

• A Write_Extended_ID_Code_1 request will always be answered and initiate an EEPROM write access

procedure in this case.

Manufacturer configuration of the ID_Code_Extension_1 register is only possible as long as the Lock_EE_PRG

flag is not yet set. In this case, the Write_Extended_ID_Code_1 request causes a write access that differs from

the procedure described on page 20. Instead of the Security_Flag procedure, the ID_Code_Extension_1 is written

to both EEPROM addresses 1 and 2 in the User Area of the EEPROM. This method of duplicate saving ensures

data consistency even in the case of an accidental interruption of the EEPROM write process during modification

of bit 3 in Extended Address Mode. Refer to Table 5.29 for an overview of the different programming and read out

options of ID_Code_Extension_1.

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