Crack NXP P87C552 Microcontroller Flash Memory

Crack NXP P87C552 Microcontroller Flash Memory needs to Using the Automatic Address Recognition feature allows a master to selectively communicate with one or more slaves by invoking the Given slave address or addresses.

All of the slaves may be contacted by using the Broadcast address. Two special Function Registers are used to define the slave’s address, SADDR, and the address mask, SADEN. SADEN is used to define which bits in the SADDR are to b used and which bits are “don’t care”.

Crack NXP P87C552 Microcontroller Flash Memory

Crack NXP P87C552 Microcontroller Flash Memory

The SADEN mask can be logically ANDed with the SADDR to create the “Given” address which the master will use for addressing each of the slaves. Use of the Given address allows multiple slaves to be recognized while excluding others. The following examples will help to show the versatility of this scheme:

Slave 0      SADDR      =      1100   0000

SADEN      =      1111 1101 Given         =       1100   00X0

In the above example SADDR is the same and the SADEN data is used to differentiate between the two slaves. Slave 0 requires a 0 in bit 0 and it ignores bit 1. Slave 1 requires a 0 in bit 1 and bit 0 is ignored. A unique address for Slave 0 would be 1100 0010 since slave 1 requires a 0 in bit 1 by readout MCU. A unique address for slave 1 would be 1100 0001 since a 1 in bit 0 will exclude slave 0. Both slaves can be selected at the same time by an address which has bit 0 = 0 (for slave 0) and bit 1 = 0 (for slave 1). Thus, both could be addressed with 1100 0000.

In a more complex system the following could be used to select slaves 1 and 2 while excluding slave 0:

Slave 0      SADDR      =      1100   0000

SADEN      =      1111 1001 Given         =       1100   0XX0

Slave 1      SADDR      =      1110   0000

SADEN      =      1111 1010 Given         =       1110   0X0X

Slave 2      SADDR      =      1110   0000

SADEN =     1111 1100 Given  =     1110   00XX

In the above example the differentiation among the 3 slaves is in the lower 3 address bits. Slave 0 requires that bit 0 = 0 and it can be uniquely addressed by 1110 0110 from Crack NXP P87C552 Microcontroller Flash Memory. Slave 1 requires that bit 1 = 0 and it can be uniquely addressed by 1110 and 0101. Slave 2 requires that bit 2 = 0 and its unique address is 1110 0011. To select Slaves 0 and 1 and exclude Slave 2 use address 1110 0100, since it is necessary t make bit 2 = 1 to exclude slave 2.