 2014 Microchip Technology Inc.

DS40001762A-page 11

MCS3122

4.5.4

SEED WORD FORMAT

The seed word is used when pairing the transmitter to

a receiver using a secure learn methodology. The seed

code word format is shown is Figure 4-3. While the

MCS3122 Flash data contains user-configurable 64-bit

seed data, the encoder will send 128-bit seed code.

The 128-bit seed code is constructed using the

user-configured seed code for the lower 64 bits of the

seed. The upper 64 bits are added by MCS3122 as 8

bytes with a 0x12 value.

FIGURE 4-3:

Serial Number

64-Bit Padded Seed Upper Value

(2)

64-Bit Configurable Seed Lower Value

32 bits

Fixed Portion

128 bit Seed

Authorization

Code

32 bits

Auth. Portion

Note 1:

MCS3122 can set a different serial number for the seed packet. This is typically set to 0xFFFFFFFF.

2:

The padded value is 0x1212121212121212.

3:

The data is sent LSB first (in this figure from right to left.