hcs200 Microchip Technology Inc., hcs200 Datasheet - Page 5

• Manufacturer Part Number: hcs200
• Description: K L Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

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:
Name
PWM
V
V
Note:
2002 Microchip Technology Inc.
S0
S1
S2
SS
DD
Note
B0
B1
B3 B2 B1 B0
ENCODER OPERATION
Number
1: Up to 7 functions can be implemented by pressing
2: Resistor (R) is recommended for current limiting.
When V
tive loads, a resistor with a minimum value
of 50
This prevents clamping of PWM at 9.0V in
the event of PWM overshoot.
Pin
1
2
3
5
6
8
+12V
more than one button simultaneously or by using a
suitable diode array.
R (Note
4 button remote control (Note
2 button remote control
PIN DESCRIPTIONS
S0
S1
S2
NC
DD
should be used in line with V
Switch input 0
Switch input 1
Switch input 2/Clock pin when in
Programming mode
Ground reference
Pulse Width Modulation (PWM)
output pin/Data pin for Program-
ming mode
Positive supply voltage
2
)
S0
NC
S1
S2
TYPICAL CIRCUITS
> 9.0V and driving low capaci-
PWM
Vss
V
NC
R (Note
+12V
PWM
DD
V
Vss
NC
Description
DD
2
)
Tx out
1
)
Tx out
DD
.
The HCS200 will wake-up upon detecting a button
press and delay approximately 10 ms for button
debounce (Figure 2-2). The synchronization counter,
discrimination value and button information will be
encrypted to form the hopping code. The hopping code
portion will change every transmission, even if the
same button is pushed again. A code word that has
been transmitted will not repeat for more than 64K
transmissions. This provides more than 18 years of use
before a code is repeated; based on 10 operations per
day. Overflow information sent from the encoder can be
used 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
occur and the current 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 code word will be completed
and the power-down will occur.
FIGURE 2-2:
Yes
RESET and Debounce Delay
Load Transmit Register
(A button has been pressed)
Word Transmission
Update Sync Info
Complete Code
Sample Inputs
Encrypt With
ENCODER OPERATION
Power-Up
Crypt Key
Released
Transmit
Buttons
(10 ms)
Buttons
Added
Stop
All
?
?
Yes
No
HCS200
DS40138C-page 5
No