HCS300-IP Microchip Technology, HCS300-IP Datasheet - Page 4

• Manufacturer Part Number: HCS300-IP
• Description: KEE LOQ Code Hopping Encoder
• Manufacturer: Microchip Technology

HCS300
2.0
As shown in the typical application circuits (Figure 2-1),
the HCS300 is a simple device to use. It requires only
the addition of buttons and RF circuitry for use as the
transmitter in your security application. A description of
each pin is described in Table 2-1.
FIGURE 2-1:
DS21137D-page 4
B4 B3 B2 B1 B0
B0
B1
Note: Up to 15 functions can be implemented by
DEVICE OPERATION
V
DD
pressing more than one button simulta-
neously or by using a suitable diode array.
5 button remote control (Note)
2 button remote control
TYPICAL CIRCUITS
S0
S1
S2
S3
S0
S1
S2
S3
PWM
V
V
LED
SS
DD
PWM
V
V
LED
SS
DD
V
DD
Tx out
Tx out
Preliminary
TABLE 2-1:
The high security level of the HCS300 is based on the
patented K
encryption algorithm based on a block length of 32 bits
and a key length of 64 bits is used. The algorithm
obscures the information in such a way that even if the
transmission information (before coding) differs by only
one bit from the information in the previous transmis-
sion, the next coded transmission will be totally differ-
ent. Statistically, if only one bit in the 32-bit string of
information changes, approximately 50 percent of the
coded transmission will change. The HCS300 will wake
up upon detecting a switch closure and then delay
approximately 10 ms for switch debounce (Figure 2-2).
The synchronized information, fixed information, and
switch information will be encrypted to form the hopping
code. The encrypted or hopping code portion of the
transmission will change every time a button is
pressed, even if the same button is pushed again.
Keeping a button pressed for a long time will result in
the same code word being transmitted until the button
is released or timeout occurs. A code that has been
transmitted will not occur again for more than 64K
transmissions. This will provide more than 18 years of
typical use before a code is repeated based on 10 oper-
ations per day. Overflow information programmed into
the encoder can be used by the decoder to extend the
number of unique transmissions to more than 192K.
If in the transmit process it is detected that a new but-
ton(s) has been pressed, a reset will immediately be
forced and the code word will not be completed. Please
note that buttons removed will not have any effect on
the code word unless no buttons remain pressed in
which case the ccurrent code word will be completed
and the power down will occur.
Name
PWM
LED
V
V
S0
S1
S2
S3
DD
SS
Number
EE
Pin
1
2
3
4
5
6
7
8
L
OQ
PIN DESCRIPTIONS
technology. A block cipher type of
Switch input 0
Switch input 1
Switch input 2/Can also be clock
pin when in programming mode
Switch input 3/Clock pin when in
programming mode
Ground reference connection
Pulse width modulation (PWM)
output pin/Data pin for
programming mode
Cathode connection for directly
driving LED during transmission
Positive supply voltage
connection
1996 Microchip Technology Inc.
Description