B.1. Initiation LFSR Function

The initiation key is sent to the Plug and Play cards in the Wait for Key state by insuring that the LFSR is in its initial state, then performing 32 writes to the ADDRESS port. The 32 writes must be exactly equal to the 32 values the LFSR will generate starting from 0x6A.

The LFSR will reset to its initial state (0x6A) any time the Plug and Play card is in the Wait for Key state and receives a write to the ADDRESS port that does not match the value currently in the LFSR. To insure that the LFSR is in the initial state, perform two write operations of value 0x00 to the ADDRESS port before sending the initiation key.

To perform the initiation key, first write the initial value of 0x6A to the ADDRESS port. Compute the next 31 values of the LFSR by first determining the shift input for the next cycle which is LFSR[1] XOR LFSR[0]. Next shift the LFSR right one bit and assign bit 7 to the shift input determined above. Write this value to the ADDRESS port and repeat.

The exact sequence for the initiation key in hexadecimal notation is:

6A,B5,DA,ED,F6,FB,7D,BE,
DF,6F,37,1B,0D,86,C3,61
B0,58,2C,16,8B,45,A2,D1,
E8,74,3A,9D,CE,E7,73,39