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| 型号： | HCS473SLSQTP |
| 厂商： | Microchip Technology Inc. |
| 英文描述： | Code Hopping Encoder and Transponder |
| 中文描述： | 跳码编码器和转发器 |
| 文件页数： | 41/68页 |
| 文件大小： | 1629K |
| 代理商： | HCS473SLSQTP |
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2002 Microchip Technology Inc.
Preliminary
DS40035C-page 39
HCS473
5.0
INTEGRATING THE HCS473
INTO A SYSTEM
Use of the HCS473 in a system requires a compatible
decoder. This decoder is typically a microcontroller with
a low frequency coil antenna and radio frequency
receiver. Example firmware routines that accept and
decrypt K
EE
L
OQ
transmissions can be found in Applica-
tion Notes and the K
EE
L
OQ
license disk.
5.1
Training the Receiver
In order for a transmitter to be used with a decoder, the
transmitter must first be ‘learned’. When a decoder
learns a transmitter, it is suggested that the decoder
stores the serial number and current synchronization
value in EEPROM. Some learning strategies have
been patented and care must be taken not to infringe
on them. The decoder must keep track of these values
for every transmitter that is learned (see Figure 5-1).
The maximum number of transmitters that can be
learned is limited only by the available EEPROM
memory. The decoder must also store the manufac-
turer’s code in order to learn a transmitter. This value
will not change in a typical system, so it is usually
stored as part of the microcontroller ROM code. Storing
the manufacturer’s code as part of the ROM code
improves security by keeping it off the external bus to
the EEPROM.
FIGURE 5-1:
TYPICAL LEARN
SEQUENCE
5.2
Decoder Operation
In a typical decoder operation (Figure 5-2), the key
generation on the decoder side is performed by taking
the serial number from a transmission and combining
that with the manufacturer’s code to create the same
secret key that was used by the transmitter. Once the
secret key is obtained, the rest of the transmission can
be decrypted. The decoder waits for a transmission
and immediately can check the serial number to
determine if it is a learned transmitter. If it is, the
encrypted portion of the transmission is decrypted
using the stored key. It uses the discrimination bits to
determine if the decryption was valid. If everything up
to this point is valid, the synchronization value
is evaluated.
Enter Learn
Mode
Wait for Reception
of a Valid Code & Seed
Generate Key
Use Generated Key
to Decrypt
Compare Discrimination
Value with Fixed Value
Equal
Wait for Reception
of Second Valid Code
(Optional)
Counters
Sequential
Exit
Learn
Unsuccessful
No
No
Yes
Yes
Learn Successful Store:
Serial Number
Encoder Key
Synchronization Counter
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相关代理商/技术参数 |
参数描述 |
|---|---|
| HCS473-SLSQTP | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Code Hopping Encoder and Transponder |
| HCS473T/SL | 功能描述:编码器、解码器、复用器和解复用器 w/ Passive Entry RoHS:否 制造商:Micrel 产品:Multiplexers 逻辑系列:CMOS 位数: 线路数量（输入/输出）:2 / 12 传播延迟时间:350 ps, 400 ps 电源电压-最大:2.625 V, 3.6 V 电源电压-最小:2.375 V, 3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Tray |
| HCS473T-I/SL | 功能描述:编码器、解码器、复用器和解复用器 w/ Passive Entry RoHS:否 制造商:Micrel 产品:Multiplexers 逻辑系列:CMOS 位数: 线路数量（输入/输出）:2 / 12 传播延迟时间:350 ps, 400 ps 电源电压-最大:2.625 V, 3.6 V 电源电压-最小:2.375 V, 3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Tray |
| HCS4870C | 制造商:Power-One 功能描述:POWER SUPPLY |
| HCS500 | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Memory Programming Specification |
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