HCS512_11 Datasheet, PDF (9/34 Pages) Microchip Technology – KEELOQ® Code Hopping Decoder system and high security

5.0 INTEGRATING THE HCS512
INTO A SYSTEM
The HCS512 can act as a stand-alone decoder or be
interfaced to a microcontroller. Typical stand-alone
applications include garage door openers and elec-
tronic door locks. In stand-alone applications, the
HCS512 will handle learning, reception, decryption,
and validation of the received code; and generate the
appropriate output. For a garage door opener, the
HCS512 input will be connected to an RF receiver, and
the output, to a relay driver to connect a motor control-
ler.
Typical systems where the HCS512 will be connected
to a microcontroller include vehicle and home security
systems. The HCS512 input will be connected to an RF
receiver and the function outputs to the microcontroller.
The HCS512 will handle all the decoding functions and
the microcontroller, all the system functions. The Serial
Output mode with a 1- or 2-wire interface can be used
if the microcontroller is I/O limited.
HCS512
6.0 DECODER PROGRAMMING
The PG306001 production programmer will allow easy
setup and programming of the configuration byte and
the manufacturer’s code.
6.1 Configuration Byte
The configuration byte is used to set system configura-
tion for the decoder. The LRN bits determine which
algorithm (Decrypt or XOR) is used for the key genera-
tion. SC_LRN determines whether normal learn (key
derived from serial number) or secure learn (key
derived from seed value) is used.
TABLE 6-1: CONFIGURATION BYTE
Bit Name
Description
0 LRN0
Learn algorithm select
1 LRN1
Not used
2 SC_LRN Secure Learn enable (1 = enabled)
3 SLEEP
SLEEP enable (1 = enabled)
4 RES1
Not used
5 RES2
Not used
6 RES3
Not used
7 RES4
Not used
TABLE 6-2:
LRN0
0
1
LEARN METHOD LRN0, LRN1
DEFINITIONS
Description
Decrypt algorithm
XOR algorithm
© 2011 Microchip Technology Inc.
DS40151E-page 9