HCS201 datasheet(5/28 Pages) MICROCHIP

5 / 28 page

DS41098C-page 5

HCS201

2.0

ENCODER OPERATION

As shown in the typical application circuits (Figure 2-1),

the HCS201 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 given in Table 2-1.

FIGURE 2-1:

TYPICAL CIRCUITS

TABLE 2-1:

PIN DESCRIPTIONS

The HCS201 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.

VDD

Tx out

VDDB

STEP

VDD

DATA

VSS

Two button remote control

Tx out

STEP

VDD

DATA

VSS

Four button remote control

B3 B2 B1 B0

Note:

Up to 7 functions can be implemented by pressing

more than one button simultaneously or by using a

suitable diode array.

STEP

VDD

DATA

VSS

VDDB

VDD

Tx out

Three button remote control with Step up regulator

VDD

2.0-6.0V

External components sample values:

R = 5.1 K

Ω

L = 390 uH

Q = 2N3904

C = 1.0 uF

D = ZHCS400CT (40V 0.4A Zetex)

(see Section 5.6 for a description of the Step Up circuit)

Name

Number

Pin Description

Switch input 0

Switch input 1

Switch input 2 / Clock pin for

Programming mode

VDDB

Battery input pin, supplies power

to the step up control circuitry

VSS

Ground reference connection

DATA

Pulse Width Modulation (PWM)

output pin / Data pin for

Programming mode

STEP

Step up regulator switch control

VDD

Positive supply voltage

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