HCS200-ISN MICROCHIP [Microchip Technology], HCS200-ISN Datasheet - Page 4

• Manufacturer Part Number: HCS200-ISN
• Description: KEELOQ CODE HOPPING ENCODER
• Manufacturer: MICROCHIP [Microchip Technology]

HCS200
2.0
As shown in Figure 2-1, the HCS200 is a simple device
to use. It requires only the addition of buttons and RF
circuitry for use as the transmitter in your security appli-
cation. A description of each pin is described in
Table 2-1.
FIGURE 2-1:
TABLE 2-1:
DS40138A-page 4
Name
PWM
(Note 2) R
V
V
Note:
S0
S1
S2
Note 1:
DD
SS
B0
B1
B3 B2 B1 B0
2:
DEVICE OPERATION
Number
When V
loads, a resistor with a minimum value of 50
should be used in line with V
clamping of PWM at 9.0V in the event of PWM
overshoot.
Pin
Up to 7 functions can be implemented by pressing
more than one button simultaneously or by using a
suitable diode array.
Resistor (R) is recommended for current limiting.
1
2
3
5
6
8
+12V
4 button remote control (Note)
(Note 2) R
2 button remote control
TYPICAL CIRCUITS
PIN DESCRIPTIONS
DD
S0
S1
S2
NC
programming mode
Ground reference connection
output pin/Data pin for program-
ming mode
Positive supply voltage connec-
tion
Switch input 0
Switch input 1
Switch input 2/Clock pin when in
Pulse width modulation (PWM)
S0
NC
S1
S2
> 9.0V and driving low capacitive
PWM
V
Vss
NC
DD
+12V
PWM
V
Vss
NC
Description
DD
DD
Tx out
. This prevents
Tx out
Preliminary
The high security level of the HCS200 is based on the pat-
ented K
length of 32 bits and a key length of 64 bits is used. The algo-
rithm 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 transmission, the next
coded transmission will be totally different. Statistically, if only
one bit in the 32-bit string of information changes, approxi-
mately 50 percent of the coded transmission will change. The
HCS200 will wake up upon detecting a switch closure and
then delay approximately 10 ms for switch debounce
(Figure 2-2). The synchronization information, fixed informa-
tion, and switch information will be encrypted to form the hop-
ping code. The encrypted or hopping code portion of the
transmission will change every time, even if the same button
is pushed again. 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 operations per day. Overflow information sent
from 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 button(s) has
been pre
code word will not be completed. Please note that but-
tons removed will no
unless no buttons remain pressed in which case the code
word will be completed and the power down will occur.
FIGURE 2-2:
EE
ssed, a reset will immediately be forced and the
L
OQ
Yes
technology. A block cipher based on a block
Reset and Debounce Delay
Load Transmit Register
(A button has been pressed)
ENCODER OPERATION
Word Transmission
Update Sync Info
Encryption Key
Complete Code
t have any effect on the code word
Sample Inputs
Encrypt With
Power Up
Released
Transmit
Buttons
(10 ms)
Buttons
Stop
Added
1996 Microchip Technology Inc.
All
?
?
Yes
No
No