APGRD001 Microchip Technology, APGRD001 Datasheet

APGRD001

Manufacturer Part Number

APGRD001

Description

REF DESIGN PKE PIC16F639

Manufacturer

Microchip Technology

Type

PKE, RKEr

Datasheets

1.APGRD002.pdf (12 pages)

2.APGRD001.pdf (26 pages)

Specifications of APGRD001

Frequency

125kHz

Processor To Be Evaluated

PIC16F639

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

For Use With/related Products

PIC16F639, PIC16F636, PIC18F2680

Lead Free Status / RoHS Status

Lead free / RoHS Compliant, Lead free / RoHS Compliant

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INTRODUCTION

Hands-free Passive Keyless Entry (PKE) is quickly

becoming mainstream in automotive remote keyless

entry applications and is a common option on new

automobile models. Instead of pressing a transmitter

button to unlock or lock a car door, it is possible to gain

vehicle access simply having a valid transponder in

your possession.

Hands-free PKE applications require bidirectional

communication

transponder units. The base unit inside the vehicle

transmits a Low-Frequency (LF) command that

searches for a transponder in the field. Once located,

the transponder in the vehicle owner’s possession then

automatically responds to the base unit. The base unit

then unlocks the car doors, if a valid authentication

response is received.

In typical PKE applications, the base station unit is

designed to output the maximum power that is allowed

by electromagnetic field radiation rules that are

mandated by government agencies. When it operates

with a 9 to 12 V

attainable antenna voltage is about 300 V

of the non-propagating property of the low-frequency

(125 kHz) signal, the signal level becomes only about

a few mV

transponder approximately two meters away from the

Author:

Youbok Lee, Ph.D.

Microchip Technology Inc.

when it is received by a typical key fob

between

PKE System Design Using the PIC16F639

of power source, the maximum

the

base

station

. Because

and

base station unit. Furthermore, due to antenna

orientation properties, the input signal level at the

transponder becomes considerably weaker if the

antenna is not oriented face-to-face with the base

station antenna.

The most probable source of PKE operation failure is

due to a weak input signal level at the transponder.

Therefore, for a reliable hands-free PKE application, it

is necessary to make the input signal strong enough

(above input sensitivity level) in any condition within the

desired communication range.

In order to make the PKE system reliable, the system

designer must consider four important parameters:

The PIC16F639 is a microcontroller (MCU) with a

three-channel analog front-end. The device’s analog

front-end features are controlled by the MCU firmware.

Because of its easy-to-use features, the device can be

used for various smart low-frequency sensing and

bidirectional communication applications.

This application note provides design circuit examples

of the smart PKE transponder using the PIC16F639

MCU. The MCU firmware examples for the circuits

shown in this application note are also available. The

given circuit and MCU firmware examples can be easily

modified for users specific applications.

Output power of the base station command,

Input sensitivity of the transponder,

Antenna directionality, and

Battery life of the transponder.

AN1024

DS01024B-page 1

Related parts for APGRD001

APGRD001 Summary of contents

Page 1

... PP transponder approximately two meters away from the © 2007 Microchip Technology Inc. base station unit. Furthermore, due to antenna orientation properties, the input signal level at the transponder becomes considerably weaker if the antenna is not oriented face-to-face with the base station antenna ...

Page 2

... LFDATA and ALERT pins of the AFE be connected to the PORTA pins externally, as shown in Figure 2. The digital section can wake up when one of the following three conditions occur: 1. AFE output at LFDATA pin, 2. AFE output at ALERT pin Any event by push button switches on PORTA. © 2007 Microchip Technology Inc. ...

Page 3

... FIGURE 2: EXAMPLE OF PASSIVE KEYLESS ENTRY (PKE) TRANSPONDER CONFIGURATION +3V 433.92 MHz RF Circuitry (UHF TX) D4 Battery (2-3.6V) air-core coil D2 © 2007 Microchip Technology Inc. Encrypted Codes Response (UHF) Ant Command (125 kHz) Ant. Y Ant Talk-back 125 kHz (125 kHz) LC Parallel Resonant Circuit Push Button Switch ...

Page 4

... The demodulated output is not available at the output pin since the input does not meet the programmed filter requirement. This ensures that the digital section will not wake-up due to unwanted input signals ms ms). OEH OEL with a PP © 2007 Microchip Technology Inc. ...

Page 5

... LC where L is the inductance of the loop and C is the capacitance. © 2007 Microchip Technology Inc. For a given LC resonant circuit, the received antenna voltage is approximately given by Equation 2 (refer to application note AN710, “Antenna Circuit Design for RFID Applications,” (DS00710) for details): ...

Page 6

... Transponder PCB Note 1: Keep the size of the air-core antenna (LCZ) as large as possible, given the PCB space available. 2: Keep the separation between the antennas as far apart as possible to reduce a mutual coupling between them. (LCY Input Pin) © 2007 Microchip Technology Inc. ...

Page 7

... Bit Setting (steps) © 2007 Microchip Technology Inc. Battery Back-up and Batteryless Modes In real-life applications, there is the chance that the battery can be momentarily disconnected from the circuit by accident, for example, if the unit is dropped onto a hard surface. If this should happen, the data stored in the MCU may not be recovered correctly ...

Page 8

... Users can use the circuits as references when they develop their own systems. Users can also refer to the PKE reference demonstration kit (P/N: APGRD001), which is available from Microchip. Start MCU Programs AFE Configuration Registers MCU in Sleep Mode Input Signal in? ...

Page 9

... The base station can detect the changes in the transponder antenna voltage and reconstruct the modulation data. © 2007 Microchip Technology Inc. AN1024 See the PIC12F635/PIC16F636/639 Device Data Sheet (DS41232) for more details of the LF talk-back (see “ ...

Page 10

... Contact Microchip sales for assistance if you want to use Figure 9 shows an example of the handshake between the base station and the transponder. Figure 10 shows a communication example between the transponder and base station units by using the firmware. ® L security security ICs in your design. © 2007 Microchip Technology Inc. ...

Page 11

... Technology Inc. AN959, “Using the PIC16F639 MCU for Smart Wireless Applications,” Application Note (DS00950), Microchip Technology Inc. TB088, “PIC16F639 Microcontroller Technical Brief (DS91088) Microchip Technology Inc. TB090, “MCP2030 Three - Channel Analog Front-End Device Overview,” Technical Brief Microchip Technology Inc. ...

Page 12

... AN1024 APPENDIX A: SOURCE CODE The complete source code, including any firmware applications and necessary support files, is available for download as a single archive file from the Microchip corporate web site, at: www.microchip.com DS01024B-page 12 © 2007 Microchip Technology Inc. ...

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... Microchip Technology Inc. AN1024 DS01024B-page 19 ...

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... Microchip Technology Inc. AN1024 DS01024B-page 21 ...

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... Microchip Technology Inc. AN1024 DS01024B-page 23 ...

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... Select Mode, Smart Serial, SmartTel, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. ...

Page 26

... Fax: 886-3-572-6459 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350 © 2007 Microchip Technology Inc. EUROPE Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 France - Paris Tel: 33-1-69-53-63-20 ...

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