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This application note fully describes the working of a
code hopping decoder implemented on a Microchip
PIC16C54 microcontroller. The PIC16C54 is smaller
than the PIC16C56 used in the normal decoder
(AN642) or the secure learn decoder (AN652). A sim -
plified learning scheme with all encoders sharing a
common key and a simplified counter synchronization
scheme has been used to reduce the code space
requirements. The use of a common key reduces the
security of the system. The simple decoder can learn
up to 15 encoders. This application note describes the
various KEELOQ
®
code hopping encoders that can be
used with the decoder, the decoder hardware, and the
various software modules comprising the system. The
software can be used to implement a stand alone
decoder or integrated with full function security sys -
tems. The decoder supports the Microchip HCS200,
HCS300, HCS301, HCS360, HCS361 and HCS410
KEELOQ Code Hopping Encoders.
AN663
KEELOQ Simple Code Hopping Decoder

Author: Steven Dawson KEY FEATURES
Microchip Technology Inc. PIC16C54
OVERVIEW Stand alone decoder
Compatible with Microchip HCS200, HCS300,
This application note fully describes the working of a HCS301, HCS360, HCS361 and HCS410
code hopping decoder implemented on a Microchip encoders
PIC16C54 microcontroller. The PIC16C54 is smaller Automatic bit rate detection
than the PIC16C56 used in the normal decoder Automatic encoder type detection
(AN642)

关键词： 解码器   KEELOQ