passive keyless entry (pke) reference design user's manual

© 2006 Microchip Technology Inc. DS21986A

Passive Keyless Entry (PKE)Reference Design

User’s Manual

Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of ourproducts. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such actsallow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding deviceapplications and the like is provided only for your convenienceand may be superseded by updates. It is your responsibility toensure that your application meets with your specifications.MICROCHIP MAKES NO REPRESENTATIONS OR WAR-RANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,WRITTEN OR ORAL, STATUTORY OR OTHERWISE,RELATED TO THE INFORMATION, INCLUDING BUT NOTLIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,MERCHANTABILITY OR FITNESS FOR PURPOSE.Microchip disclaims all liability arising from this information andits use. Use of Microchip devices in life support and/or safetyapplications is entirely at the buyer’s risk, and the buyer agreesto defend, indemnify and hold harmless Microchip from any andall damages, claims, suits, or expenses resulting from suchuse. No licenses are conveyed, implicitly or otherwise, underany Microchip intellectual property rights.

DS21986A-page ii

Trademarks

The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, PowerSmart, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.

AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Linear Active Thermistor, MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, Real ICE, rfLAB, rfPICDEM, 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.

© 2006, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.

Printed on recycled paper.

© 2006 Microchip Technology Inc.

Microchip received ISO/TS-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona and Mountain View, California in October 2003. The Company’s quality system processes and procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified.

PKE REFERENCE DESIGNUSER’S MANUAL

Table of Contents

Preface ........................................................................................................................... 1

Chapter 1. System Overview1.1 Overview ........................................................................................................ 61.2 Operational Overview ..................................................................................... 71.3 Features ......................................................................................................... 7

1.3.1 LF Initiator ................................................................................................... 71.3.2 Key Fob ....................................................................................................... 71.3.3 RF Receiver ................................................................................................ 8

1.4 Reference Documents .................................................................................... 8

Chapter 2. Low-Frequency Initiator Module2.1 Introduction ................................................................................................... 102.2 Hardware ...................................................................................................... 10

2.2.1 Microcontroller ........................................................................................... 102.2.2 Configurable Inputs ................................................................................... 102.2.3 LF Transmitter ........................................................................................... 102.2.4 Network Interfaces .................................................................................... 102.2.5 Power ........................................................................................................ 10

2.3 Software ....................................................................................................... 12

Chapter 3. PKE Transmitter-Transponder3.1 Introduction ................................................................................................... 143.2 Hardware ...................................................................................................... 14

3.2.1 Transmitter ................................................................................................ 15

3.3 Software ....................................................................................................... 173.3.1 Dual Encoder Operation ............................................................................ 203.3.2 Code Hopping Code Word Data Format ................................................... 203.3.3 EEPROM Organization ............................................................................. 23

Chapter 4. Remote Keyless Entry Receiver-Decoder Module4.1 Introduction ................................................................................................... 264.2 Hardware ...................................................................................................... 26

4.2.1 UHF Receiver ............................................................................................ 264.2.2 Microcontroller ........................................................................................... 264.2.3 Network Interface ...................................................................................... 274.2.4 Power Supply ............................................................................................ 274.2.5 Connectors ................................................................................................ 28

4.3 Software ....................................................................................................... 304.3.1 Modules Overview ..................................................................................... 30

Worldwide Sales and Service .................................................................................... 33

© 2006 Microchip Technology Inc. DS21986A-page iii

PKE Reference Design User’s Manual

NOTES:

DS21986A-page iv © 2006 Microchip Technology Inc.


Preface

INTRODUCTION

This chapter contains general information that will be useful to know before using the PKE Reference Design. Items discussed in this chapter include:

• Document Layout• Conventions Used in this Guide• Recommended Reading• The Microchip Web Site• Customer Support

DOCUMENT LAYOUT

This document describes a Passive Keyless Entry (PKE) system upgrade to an existing Remote Keyless Entry (RKE) application. The manual layout is as follows:

• Chapter 1. “System Overview” – Describes the PKE system upgrade to an existing Remote Keyless Entry (RKE) application overview.

• Chapter 2. “Low-Frequency Initiator Module” – Describes the Low-Frequency Magnetic Transmitter.

• Chapter 3. “PKE Transmitter-Transponder” – Describes the Remote Keyless Entry unit as a solution for Passive and RKE Keyless Entry applications.

• Chapter 4. “Remote Keyless Entry Receiver-Decoder Module” – Describes the Remote Keyless Entry Receiver-Decoder module as a target board for RKE and PKE message transmissions.

NOTICE TO CUSTOMERS

All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available.

Documents are identified with a “DS” number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is “DSXXXXXA”, where “XXXXX” is the document number and “A” is the revision level of the document.

For the most up-to-date information on development tools, see the MPLAB® IDE on-line help. Select the Help menu, and then Topics to open a list of available on-line help files.

© 2006 Microchip Technology Inc. DS21986A-page 1

Preface

CONVENTIONS USED IN THIS GUIDE

This manual uses the following documentation conventions:

DOCUMENTATION CONVENTIONS

RECOMMENDED READING

It is recommended that you become familiar with the documents listed below, prior to using the PKE Reference Design Kit.

PICkit™ 2 Microcontroller Programmer User’s Guide (DS51553)

Consult this document for instructions on how to use the PICkit 2 Microcontroller Programmer hardware and software.

AMHRRQ3-433 Telecontrolli Data Sheet (DS.0015-1.pdf)

AMHRR3-433 Telecontrolli Data Sheet (DS.0016-9.pdf)

PIC12F635/PIC16F636/639 Data Sheet (DS41232)

Data sheet for the PIC12F635/PIC16F636/639 8/14-pin Flash-based, 8-bit CMOS microcontrollers with nanoWatt technology.

PIC16F688 Data Sheet (DS41203)

Data sheet for the PIC16F688 14-pin Flash-based 8-bit CMOS microcontrollers with nanoWatt technology.

Description Represents Examples

Code (Courier font):

Plain characters Sample codeFilenames and paths

#define STARTc:\autoexec.bat

Angle brackets: < > Variables <label>, <exp>

Square brackets [ ] Optional arguments MPASMWIN [main.asm]

Curly brackets and pipe character: { | }

Choice of mutually exclusive argu-ments; An OR selection

errorlevel {0|1}

Lowercase characters in quotes

Type of data “filename”

Ellipses... Used to imply (but not show) addi-tional text that is not relevant to the example

list [“list_option..., “list_option”]

0xnnn A hexadecimal number where n is a hexadecimal digit

0xFFFF, 0x007A

Italic characters A variable argument; it can be either a type of data (in lowercase characters) or a specific example (in uppercase characters).

char isascii (char, ch);

Interface (Arial font):

Underlined, italic text with right arrow

A menu selection from the menu bar File > Save

Bold characters A window or dialog button to click OK, Cancel

Characters in angle brackets < >

A key on the keyboard <Tab>, <Ctrl-C>

Documents (Arial font):

Italic characters Referenced books MPLAB® IDE User’s Guide



MCP201 LIN Transceiver with Voltage Regulator Data Sheet (DS21730)

Data sheet for the MCP201 LIN transceiver. Gives an overview of the device including modes of operation and electrical characteristics.

Modular PICmicro® Mid-Range MCU Code Hopping Decoder Application Note AN742 (DS00742)

Application note describes a KEELOQ code hopping decoder implemented on a Microchip mid-range PICmicro microcontroller.

Using the PIC16F639 MCU for Smart Wireless Applications Application Note AN959 (DS00959)

Application note describing the PIC16F639 as a suitable microcontroller for bidirectional communications and low-frequency sensing applications.

HCS365 Data Sheet (DS41109)

Data sheet for the HCS365 KEELOQ code hopping encoder.

Low-Frequency Magnetic Transmitter Design Application Note AN232 (DS00232

Application note covering the basic aspects to consider when designing the transmitter portion of a LFMC link.

PIC18F2585/2680/4585/4680 Data Sheet (DS39625)

Data sheet for the PIC18F2585/2680/4585/4680 28/40/44-pin enhanced Flash microcontrollers with ECAN™ technology, 10-bit A/D and nanoWatt technology.

TC4421/TC4422 9A High-Speed MOSFET Drivers Data Sheet (DS21420)

Data sheet for the TC4421/TC4422 9A High-Speed MOSFET Driver. Gives an overview of the device including electrical characteristics.

DS21986A-page 3 © 2006 Microchip Technology Inc.

Preface

THE MICROCHIP WEB SITE

Microchip provides online support via our web site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information:

• Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s guides and hardware support documents, latest software releases and archived software

• General Technical Support – Frequently Asked Questions (FAQs), technical support requests, online discussion groups, Microchip consultant program member listing

• Business of Microchip – Product Selector Guide, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives

CUSTOMER SUPPORT

Users of Microchip products can receive assistance through several channels:

• Distributor or Representative• Local Sales Office• Field Application Engineer (FAE)• Technical Support• Development Systems Information Line

Customers should contact their distributor, representative or field application engineer (FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document.

Technical support is available through the web site at: http://support.microchip.com



NOTES:



Chapter 1. System Overview

1.1 OVERVIEW

This manual describes a Passive Keyless Entry (PKE) system upgrade to an existing Remote Keyless Entry (RKE) application.

The key fob design contains a PIC16F639 with a integrated three-axis Analog Front-End (AFE).

The Low-Frequency Initiator is implemented in a PIC18F2680.

This design has been optimized to integrate into an existing model platform without substantial modification. Operational flexibility is the key to the overall concept with many scalable features that are end-of-line programmable by customer, dealer or factory.

FIGURE 1-1: PKE BLOCK DIAGRAM

LFInitiator

Trigger

KEYFOB

3-Axis

RF

Transmitter

Encoder

RKEReceiver

AFE

RFReceiver

Decoder

Drivers

Buttons

On-Vehicle

LIN LockActuator

125 kHz

434 MHz



1.2 OPERATIONAL OVERVIEW

When the Low-Frequency (LF) Initiator detects a trigger input, a coded 125 kHz message is transmitted. Any transponder within range of this signal receives this message and validates the coded data field. If the Initiator is recognized, a RF (433.92 MHz) KEELOQ® encoded message is transmitted. A standard RKE receiver decodes this packet and, if recognized, the appropriate action is taken.

To reduce current consumption, the LF Initiator does not poll for transponders continuously. A trigger event wakes the initiator from Sleep or Power-down (see Figure 1-1). The trigger input can be any type or source such as:

• Commanded over one of the networks• Infra-red under door handle• Simple microswitch activated by the door handle mechanism• Capacitive proximity detector sensing a change in a field by a hand approaching

the handle

The application described herein uses a microswitch input for simplicity. As delivered, the LF initiator will continuously poll for the transponder. This is to facilitate orientation and range evaluation.

The transponder key fob can operate as a regular push button RKE fob. When a valid LF field message is sensed, the microcontroller responds as if a sixth phantom button were pushed and transmits a unique function code.

The RF Receiver/Decoder combination can include a KEELOQ Security IC. Typical decoders are the HCS500, HCS512 or HCS515. In the case of this design, a custom-programmed PICmicro® mid-range microcontroller was used.

1.3 FEATURES

1.3.1 LF Initiator

Refer to Microchip Application Note AN232, “Low-Frequency Magnetic Transmitter Design” (DS00232). Features of the LF Initiator are as follows:

• Commanded by various types of inputs• Simple momentary switch• Proximity detector• Serial-numbered challenge• CAN and LIN network support

1.3.2 Key Fob

Refer to Microchip Application Note AN959, “Using the PIC16F639 MCU for Smart Wireless Applications” (DS00959). Features of the key fob are as follows:

• Functionally compatible with Microchip’s HCS365 encoder• Supports up to five push button inputs• Two LED outputs for valid button and valid low-frequency challenge indication


System Overview

1.3.3 RF Receiver

Refer to Microchip Application Note AN742 “Modular PICmicro® Mid-Range MCU CodeHopping Decoder” (DS00742). Features of the RF Receiver are as follows:

• Supports two manufacturer’s codes• Compatible with Microchip’s HCS200, HCS201, HCS300, HCS301, HCS360 and

HCS361 encoders• Automatic baud rate detection• Automatic Normal or Secure learn detection• Six learnable transmitters

1.4 REFERENCE DOCUMENTS

RF Receiver-Decoder

1. “AMHRRQ3-433” Telecontrolli Data Sheet, “DS.0015-1.pdf”2. “AMHRR3-433” Telecontrolli Data Sheet, “DS.0016-9.pdf”3. “PIC12F635/PIC16F636/639 Data Sheet” (DS41232), Microchip Technology Inc.4. “PIC16F688 14-pin Flash-Based 8-Bit Data Sheet” (DS41203), Microchip

Technology Inc.5. “MCP201 LIN Transceiver with Voltage Regulator Data Sheet” (DS21730),

Microchip Technology Inc.6. “Modular PICmicro® Mid-Range MCU Code Hopping Decoder”, Application Note

AN742 (DS00742), Microchip Technology Inc.

RKE/PKE Key Fob

1. “PIC12F635/PIC16F636/639 Data Sheet” (DS41232), Microchip Technology Inc.2. “Using the PIC16F639 MCU for Smart Wireless Applications”, Application Note

AN959 (DS00959), Microchip Technology Inc.3. “HCS365 Data Sheet” (DS41109), Microchip Technology Inc.4. “Low-Frequency Magnetic Transmitter Design”, Application Note AN232

(DS00232), Microchip Technology Inc.

LF Initiator

1. “PIC18F2585/2680/4585/4680 Data Sheet” (DS39625), Microchip Technology Inc.

2. “TC4421/TC4422 9A High-Speed MOSFET Drivers Data Sheet” (DS21420), Microchip Technology Inc.

3. “Low-Frequency Magnetic Transmitter Design”, Application Note AN232 (DS00232), Microchip Technology Inc.



NOTES:



Chapter 2. Low-Frequency Initiator Module

2.1 INTRODUCTION

The LF transmitter is derived from the design described in Application Note AN232, ”Low-Frequency Magnetic Transmitter Design” (DS00232).

2.2 HARDWARE

2.2.1 Microcontroller

A PIC18F2680 was selected for the LF controller based on the wide range of peripherals available on the chip. The PIC18F2680 has both a CAN controller and a LIN-compatible EAUSART to interface to in-vehicle networks. The Capture/Compare/PWM module lends itself to generation of the 125 kHz square wave needed as the LF carrier.

2.2.2 Configurable Inputs

Two 12V tolerant inputs are provided for triggers. Both of these PCB circuits can be reconfigured for a variety of input types. Refer to the schematic in Figure 2-1. For example, if one of the inputs is a momentary switch to ground:

1. Substitute a 0Ω resistor for R2.2. Remove R3 and D3.3. Replace D2 with a 30K resistor.

2.2.3 LF Transmitter

A high-current MOSFET driver (TC4422) is driven by the PWM output of the microcontroller, and in turn, drives the resonant tank circuit consisting of TX coil (L1) and C2. This output circuit generates a magnetic field with a voltage of up to 320V peak-to-peak.

2.2.4 Network Interfaces

Network connectivity is provided by a MCP201 LIN transceiver and a MCP2551 CAN transceiver.

2.2.5 Power

Power can be supplied through either J1 power jack, J3 CAN plug or J4 LIN connection. Voltage should be in the range of 8-18 VDC. The automotive-grade voltage regulator is reverse-battery, transient and load-dump protected.

To reduce power consumption in key-off situations, the power-on LED may be removed.



FIGURE 2-1: SCHEMATIC – LOW-FREQUENCY INITIATOR

PW

M

PW

M

VC

C

VC

C

VC

C

VC

C

+1

2 V

DC

VC

C

VC

C

+12 V

DC

VC

C+

12 V

DC

400V

P3476-N

D

R6

15K

R6

15K

R1

01

20

R1

01

20

L2

DO

5022P

L2

DO

5022P

D3

1N

5819

D3

1N

5819

C7

0.1

uF

C7

0.1

Y1

20.0

MH

z

Y1

20.0

R5

1K

R5

1K

D5

1N

5819

D5

1N

5819

D8

10

MQ

10

0N

D8

10

MQ

10

0N

D7

10

MQ

10

0N

D7

10

MQ

10

0N

D2

1N

5819

D2

1N

5819

CA

NH

7

GN

D2

CA

NL

6

VC

C3

TX

D1

RX

D4

RE

F5

RS

8

U2 M

CP

25

51

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CP

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C8

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LE

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D4

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J1

J1

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KR

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C4

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C5

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C5

1.0

C9

0.2

00LS

C9

0.2

00LS

D6

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4148

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J4

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R7

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1 3 5

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J3

CO

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CO

N6

A

MC

LR

/VP

P1

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C1/C

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0/A

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1/A

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RA

2/A

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Low-Frequency Initiator Module

2.3 SOFTWARE

The LF message shown in Figure 2-2 is transmitted when the trigger event is detected. As shown, the module will wait up to 50 ms after the challenge for a response from the RF Receiver module. This notification is sent over the LIN data line. If no response is received, the module will send the same message two more times, and then enter power-down, awaiting another trigger.

FIGURE 2-2: LF CHALLENGE DATA FORMAT

The LF challenge message consists of a 125 kHz carrier modulated as follows:

1: A 4 ms ON to settle the receiving AGC.

2: 500 μs OFF.

3: 2 ms ON followed by a 2 ms OFF to enable the receiver output filter. This pattern is dependant on the configuration setting of the receiving AFE.

4: 16 Least Significant bits (LSb) of the module serial number, PWM encoded (see Figure 2-3).

5: 50 ms OFF, waiting for a valid response from the RF receiver.

The challenge code portion of the message is to ensure that only previously learned transponders are hailed. All others will remain silent. This challenge code may be expanded or reduced by changes to the firmware to address individual application requirements. For this design, 16 bits were deemed sufficient.

FIGURE 2-3: CODE WORD DATA TRANSMISSION FORMAT (PWM)

Transmission Direction LSb First

Challenge Code Portion (16 Bits)

Least Significant bits of Serial Number(16 Bits)

4 ms

125 kHz Base Frequency

UHF Response Slot Wake-Up 125 kHz Preamble

500

μs

2 ms 2 ms 50 msGuard Time

LOGIC ‘0’

LOGIC ‘1’

BitPeriod



NOTES:



Chapter 3. PKE Transmitter-Transponder

3.1 INTRODUCTION

The RKE Key Fob unit is a complete solution for PKE and RKE applications in a key fob type form factor. The board was designed to accept a PIC16F636 or a PIC16F639 microcontroller. With minor modifications, it will also support a PIC12F635.

Some features of this design are:

• Up to five push button inputs• One or two LED outputs• 433.92 MHz transmitter• 3-axis low-frequency receiver

3.2 HARDWARE

A PIC16F636, installed pin 1 justified at location U1, will support RKE applications. Since the PIC16F636 shares the same pinout as the PIC16F639 on its upper most pins, the only function lost is the on-chip low-frequency analog front-end.

For PKE applications, a PIC16F639 and the associated low-frequency receiver coils are installed.

The four buttons (S1-S4) on the transmitters are connected to the appropriate inputs on the microcontroller (S1-S4). The user may activate any combination of encoder inputs transmitting any of the 15 possible function codes. The RFEN output option is not used by the demonstration transmitter and should be disabled as this function shares its output with a button input. If RFEN is enabled, the button input will be lost. See Section 3.3 “Software”.

Button S5 is not directly associated with a specific function code bit, but rather transmits a user-defined function code stored in EEPROM data memory.

The microcontroller Flash program and EEPROM data memory may be programmed through J1. This connector is pinout compatible with PICkit™ 1 and PICkit™ 2 programmers.



TABLE 3-1: I/O CONNECTIONS

3.2.1 Transmitter

The RF oscillator uses a Surface Acoustic Wave (SAW) resonator that operates at 433.92 MHz.

The Programming Connector (J1) enables In-Circuit Serial Programming™ (ICSP™). The transmitter can therefore be re-configured or re-programmed without removing the microcontroller from the board.

FIGURE 3-1: J1 PROGRAMMING CONNECTOR

PORT Pin Function Notes

Inputs

RA0 Switch 5 ICSP™ Data

RA1 LF Data Input ICSP Clock

RA2 Switch 3

RA3 Switch 2 ICSP MCLR

RA4 Switch 1

RA5 Switch 4

Outputs

RC0 RF Active LED

RC4 LF Challenge LED

RC5 RF Data Out

Others

RC1 Internally connected on PIC16F639 not used on PIC16F636

RC2 Internally connected on PIC16F639 not used on PIC16F636

RC3 Internally and externally connected on PIC16F639 not used on PIC16F636

Note: The design and layout of this transmitter is not sufficient to ensure compliance with EC or FCC regulations.

123456

MCLR

VCC

ICSPDAT

no connection

VSS

ICSPCLK


PKE Transmitter-Transponder

FIGURE 3-2: SCHEMATIC – RF RECEIVER/DECODER USING THE PIC16F639

CS

n

ICS

PC

LK

LF

DA

TA

ICS

PD

AT

LC

CO

MLX

LY

PW

M

SC

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16

F6

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3.3 SOFTWAREThe transponder firmware is functionally based on the Microchip HCS365 KEELOQ encoder. See the “HCS365 Data Sheet” (DS41109) for more information. Additional routines have been added to initialize and interface to the internal low-frequency analog front-end of the PIC16F639.

The transponder key fob operates as a standard 5-button RKE fob, when not being challenged by a Low-Frequency Initiator signal. The microcontroller responds as if a sixth or a phantom button were pushed, when a valid LF field message is sensed and verified.

The transponder will normally be in a low-power Sleep mode. When a switch input is taken low or a LF challenge is received, the device will wake-up and go through debounce delay of 20 ms before the switch value is latched. The device will then read the configuration options and depending on the configuration options, it will determine what the data and modulation format will be for the transmission. The transmission will consist of a stream of code words. The code words are transmitted after the button is pressed and as long as the buttons are held down or a time out occurs. The code word format can be either a code hopping format or a seed format.

The time-out time can be selected with the Time-out Select (TSEL) configuration option. This option allows the time out to be disabled or set to 0.8s, 3.2s or 25.6s. When a time out occurs, the device will go into Sleep mode to protect the battery from draining when a button gets stuck.

If during the transmit process a new button is detected, the current code word will be aborted, a new code word will be transmitted and the time-out counter will reset. If all the buttons are released, a minimum number of code words will still be completed. The minimum code words can be set to 1, 2, 4 or 8 using the minimum code words (MTX) configuration option. If the time for transmitting the minimum code words is longer than the time-out time, the device will not complete the minimum code words.

A summary table of all the options is given in Section 3.3.3 “EEPROM Organization”.

Note 1: The transponder is initially supplied pre-programmed with the KEELOQ encryption algorithm. The program memory and EEPROM data memory are read-protected.

2: The software source files supplied on the CD with this transponder have the KEELOQ encryption routines deleted. If a new hex file is assembled using these source files and programmed into the microcontroller, the original KEELOQ hopping code will be overwritten and lost.

3: Contact Microchip Technology for information about KEELOQ Security ICs and licensing options.



The software includes four assemble-time conditional options. These options are enabled by removing the semi-colon in column 1 of the code line.

Select Processor, enable only one below:#DEFINE P12F635 1 ;Sets environment for PIC12F635#DEFINE P16F636 1 ;Sets environment for PIC16F636#DEFINE P16F639 1 ;Sets environment for PIC16F639

Select PORTA buttons to be connected to ground with internal pull-ups OR, connected to VCC with internal pull-downs:

#DEFINE pullup 1 ;Set to select pull-ups on PORT A.;For pull-downs, comment out.

Since the in-circuit emulator does not support Sleep:#DEFINE ICEmul 1 ;Is set, device will not SLEEP, but will

;loop forever

Select option not to Encrypt:#DEFINE NoEncryption 1



FIGURE 3-3: FLOWCHART – DEVICE OPERATION

Start

Sample

Increment

Seed

Time Out?

Encrypt

No

No

Yes

Get Config

TX?

Counter

Transmit

MTX?

NoButtons?

SeedTime?

Read Seed

Stop

Yes

Yes

No

Yes

No

No

Yes

YesYes SeedButton?

No

NewButtons?

No

LF

No

YesData?

Receive

Valid

No

YesRequest?

Buttons

Challenge



3.3.1 Dual Encoder Operation

The transponder contains two transmitter Configuration Words, serial numbers, encoder keys, discrimination values, counters and seed values. This means that the transponder can be used as two independent encoders. The code word is calculated using one of two possible encoder configurations. Most options for code word and modulation formats can be different from Encoder 1 and Encoder 2, but LED and RF transmitter options have to be the same. The Shift input pin is used to select between the encoder configurations. A low on the Shift pin will select Encoder 1 and a high will select Encoder 2.

3.3.2 Code Hopping Code Word Data Format

A code hopping code word consists of 32 bits of code hopping data, 32 bits of fixed code and between 3 and 5 bits of status information. Various code word formats are shown in Figure 3-4 for KEELOQ encoder compatible transmissions.



FIGURE 3-4: CODE WORD DATA FORMAT

Fixed Code Portion (32 Bits)

CRC2 Bits

VLOW1 Bit

Serial Number(28 Bits)

C1 C0 S2 S1 S0 S3

BUT4 Bits

CounterOverflow

2 BitsDISC

10 Bits

Synchronization

16 BitsCounter

15 0

S1S2 S0 S3 OVR1 OVR0


Hopping Code Portion (32 Bits)

With XSER = 0, 16-bit Counter, QUEN = 0

Status Information(3 Bits)

BUT4 Bits


QUE2 Bits

CRC2 Bits

VLOW1 Bit


Q1 Q0 C1 C0

BUT4 Bits

CounterOverflow

2 BitsDISC

10 Bits

Synchronization

16 BitsCounter

15 0

S2 S1 S0 S3 OVR1 OVR0





QUE2 Bits

CRC2 Bits

VLOW1 Bit


Q1 Q0 C1 C0 S2 S1 S0 S3

BUT4 Bits

DISC8 Bits

Synchronization

20 BitsCounter

19 0

S2 S1 S0 S3




BUT4 Bits


CRC2 Bits

VLOW1 Bit


C1 C0

BUT4 Bits

DISC8 Bits

Synchronization

20 BitsCounter

19 0

S2 S1 S0 S3






FIGURE 3-5: CODE WORD DATA FORMAT, NO ENCRYPTION

TABLE 3-2: FUNCTION CODES

Button Function

S0 F[xx1x]

S1 F[x1xx]

S2 F[1xxx]

S3 F[xxx1]

S4 User Programmable

LF Challenge User Programmable

Note 1: The function code is repeated in the encrypted and unencrypted data of a transmission.


CRC2 Bits

VLOW1 Bit

Serial Number 1(28 Bits)

C1 C0 S2 S1 S0 S3

BUT4 Bits

S1S2 S0 S3


With XSER = 0, 16-bit Counter, QUEN = 0, S<3:0> not equal ‘0111’


BUT4 Bits



QUE2 Bits

CRC2 Bits

VLOW1 Bit


Q1 Q0 C1 C0

BUT4 Bits

S2 S1 S0 S3



USER14 Bits

USER08 Bits

Data 71h Data 72h

Serial Number 2(16 Bits)USER1

4 BitsUSER08 Bits

Data 71h Data 72h


CRC2 Bits

VLOW1 Bit


C1 C0 S2 S1 S0 S3

BUT4 Bits

S1S2 S0 S3

With XSER = 0, 16-bit Counter, QUEN = 0, S<3:0> equal ‘0111’


BUT4 Bits



QUE2 Bits

CRC2 Bits

VLOW1 Bit


Q1 Q0 C1 C0

BUT4 Bits

S2 S1 S0 S3

With XSER = 1, 16-bit Counter, QUEN = 1, S<3:0> equal ‘0111’





3.3.3 EEPROM Organization

A summary of the transponder EEPROM organization is shown in Tables 3-3, 3-4 and 3-5. The address column shows the starting address of the option and its length, or bit position. Options larger than 8 bits are stored with the MSb at the given address, and enough consecutive 8-bit blocks are reserved for the entire option size. Options such as SEED, which has a length that is not an exact multiple of 8 bits, are stored right justified in the reserved space such that additional smaller options, like SDBT, may be stored in the same address as the MSb.

TABLE 3-3: ENCODER 1 (SHIFT = 0)

SymbolAddress

(Bits)Description(1)

KEY1 1E: 64 bits Encoder Key

SEED1 14: 60 bits Encoder Seed Value

SYNC1 00: 20 bits00: 18 bits

Encoder Synchronization Counter (CNTSEL=1)Encoder Synchronization Counter (CTNSEL = 0) plus overflow

SER1 10: 32 bits Encoder Serial Number

DISC1 1C: 10 bits Encoder Discrimination value

MSEL1 1C: ---- 3--2 Transmission ModulationFormat

Value Format

00b PWM

01b Manchester

10b VPWM

11b PPM

HSEL1 1C: ---4 ---- Header Select 4 TE = 0 10 TE = 1

XSER1 1C: --5- ---- Extended Serial Number 28 bits = 0 32 bits = 1

QUEN1 1C: -6-- ---- Queue Counter Enable Disable = 0 Enable = 1

STEN1 1C: 7--- ---- Start/Stop Pulse Enable Disable = 0 Enable = 1

LEDBL1 3F: -6-- ---- Low-Voltage LED Blink Never = 0 Once = 1

LEDOS1 3F: 7--- ---- LED On-Time Select(1) 50 ms = 0 100 ms = 1

SDLM1 3C: ---- ---0 Limited Seed Disable = 0 Enable = 1

SDEN1 3C: ---- --1- Seed Enable Disable = 0 Enable = 1

SDMD1 00: 7--- ---- Seed Mode User = 0 Production = 1

SDBT1 14: 7654 ---- Seed Button Code

SDTM1 3C: ---- 32-- Time Before Seed Code Word(1)

Value Time (s)

00b 0.0

01b 0.8

10b 1.6

11b 3.2

BSEL1 3C: --54 ---- Transmission Baud Rate Select(1)

Value TE (μs)

00b 100

01b 200

10b 400

11b 800

GSEL1 3C: 76-- ---- Guard Time Select(1) Value Time (ms)

00b 0.0

01b 6.4

10b 51.2

11b 102.4

Note 1: All Timing values vary ±10%.



TABLE 3-4: ENCODER 2 (SHIFT = 1)

SymbolAddress


KEY2 34: 64 bits Encoder Key

SEED2 2A: 60 bits Encoder Seed Value

SYNC2 08: 20 bits08: 18 bits

Encoder Synchronization Counter (CNTSEL = 1)Encoder Synchronization Counter (CTNSEL = 0) plus overflow

SER2 26: 32 bits Encoder Serial Number

DISC2 32: 10 bits Encoder Discrimination value

MSEL2 32: ---- 3--2 Transmission ModulationFormat

Value Format

00b PWM

01b Manchester

10b VPWM

11b PPM

HSEL2 32: ---4 ---- Header Select 4 TE = 0 10 TE = 1

XSER2 32: --5- ---- Extended Serial Number 28 bits = 0 32 bits = 1

QUEN2 32: -6-- ---- Queue Counter Enable Disable = 0 Enable = 1

STEN2 32: 7--- ---- Start/Stop Pulse Enable Disable = 0 Enable = 1

LEDBL2 3D: -6-- ---- Low-Voltage LED Blink Never = 0 Once = 1

LEDOS2 3D: 7--- ---- LED On-Time Select(1) 50 ms = 0 100 ms = 1

SDLM2 3E: ---- ---0 Limited Seed Disable = 0 Enable = 1

SDEN2 3E: ---- --1- Seed Enable Disable = 0 Enable = 1

SDMD2 08: 7--- ---- Seed Mode User = 0 Production = 1

SDBT2 2A: 7654 ---- Seed Button Code

SDTM2 3E: ---- 32-- Time Before Seed Code Word(1)

Value Time (s)

00b 0.0

01b 0.8

10b 1.6

11b 3.2

BSEL2 3E: --54 ---- Transmission Baud Rate Select(1)

Value TE (μs)

00b 100

01b 200

10b 400

11b 800

GSEL2 3E: 76-- ---- Guard Time Select(1) Value Time (ms)

00b 0.0

01b 6.4

10b 51.2

11b 102.4

Note 1: All Timing values vary ±10%.



TABLE 3-5: DEVICE OPTIONS

SymbolAddress


WAKE 3F: ---- --10 Wake-up(1) Value Value

00b No Wake-up

01b 75 ms 50%

10b 50 ms 33.3%

11b 100 ms 16.6%

CNTSEL 3F: ---- -2-- Counter Select 16 bits = 0 20 bits = 1

VLOWL 3F: ---- 3--- Low-Voltage Latch Enable Disable = 0 Enable = 1

VLOWSEL 3F: ---4 ---- Low-Voltage Trip Point Select(2)

2.2 V = 0 3.2V = 1

PLLSEL 3F: --5- ---- PLL Interface Select ASK = 0 FSK = 1

MTX 3D: ---- --10 Minimum Code Words Value Value

00b 1

01b 2

10b 4

11b 8

SLEEP 3D: ---- 3--- Sleep Output Enable Disable = 0 Enable = 1

WAIT 3D: ---- -2-- Wait for Step-Up Regulator Disable = 0 Enable = 1

TSEL 3D: --54 ---- Time-out Select(1) Value Time(s)

00b Disabled

01b 0.8

10b 3.2

11b 25.6

S4CODE 40: --54 32-- Switch 4 Button Code

S5CODE 41: --54 32-- Switch 5 Button Code

PKECODE 42: --54 32-- PKE Challenge Received Code

Note 1: All Timing values vary ±10%.2: Voltage thresholds are ±100 mV.



Chapter 4. Remote Keyless Entry Receiver-Decoder Module

4.1 INTRODUCTION

The Remote Keyless Entry Receiver-Decoder module serves as a target board for RKE and PKE transmissions. Visual indications of function codes, as well as, an in-vehicle network interface are included.

This module consists of a UHF receiver, microcontroller, power supply, LED indicators and a network physical interface.

FIGURE 4-1: RKE RECEIVER/DECODER

4.2 HARDWARE

4.2.1 UHF Receiver

The RF input is an AM super-regenerative compact hybrid module, which is used to capture undecoded data from an AM Transmitter. This module has very high frequency stability over a wide operating temperature and is tolerant of mechanical vibrations or manual handling. A laser-trimmed, on-board inductor removes the need for any adjustable components. Either 433.92 MHz or 315 MHz may be supplied with the board. A CMOS/TTL output supports data rates up to 2000 Hz. This input to the receiver module is connected to the microcontroller PORTA bit 2 INT pin. For more information on the receiver module, see the Telecontrolli Data Sheets “DS.0015-1.pdf” and “DS.0016-9.pdf” available on the PKE Reference Design CD-ROM (DS51575).

4.2.2 Microcontroller

a) The microcontroller can be any one of the 14-pin PICmicro® microcontroller family members, but it is usually a PIC16F636 or a PIC16F688. The PIC16F636 has on-chip KEELOQ encoder/decoder hardware, while the PIC16F688 has an Enhanced Addressable USART (EAUSART) that supports the Local Interconnect Network (LIN) and SAE J2602 protocol. In addition to the RF data input described above, the following table shows the I/O port connections.

DataINRadio Rec.

Microcontroller

LEARN SW

Function LEDS

TransceiverBus

Network

LEARN LEDVLOW LED



TABLE 4-1: I/O CONNECTIONS

The microcontroller Flash program and EEPROM data memory may be programmed through J2. This connector is pinout compatible with PICkit™ 1 and PICkit™ 2 programmers.

See the “PIC12F635/16F636/639 Data Sheet” (DS41232) or the “PIC16F688 Data Sheet” (DS41203) for additional information.

4.2.3 Network Interface

This section of the board may not be populated, depending upon the end application. If this section needs to be assembled, a complete bill of materials is available.

A MCP201 (or MCP202) LIN-bus transceiver is used for the physical slave bus driver to connect to a LIN or J2602-compatible network. A Zener diode protects the LIN bus pin from transient voltages. The capacitor between the LIN-bus pin and ground should have its value adjusted for the particular network topology. A large pull-up resistor on the FAULT/SLPS pin ensures that the device resets to a standard slope control profile.

See the “MCP201 LIN Transceiver with Voltage Regulator Data Sheet” (DS21730) for more information.

4.2.4 Power Supply

Power can be supplied to the board by way of either a J3 (5.5 mm x 2.5 mm) power jack or through J1 (AMP 770969). Voltage should be in the range of 8-18 VDC. The automo-tive-grade voltage regulator is reverse-battery, transient and load-dump protected.

To reduce power consumption in key-off situations, the power-on LED may be removed.

PORT Pin Function Notes

Inputs

RA0 Jumper E2 to GND, available to user ICSP™ Data

RA2 RF Data input

RA3 LEARN push button input ICSP MCLR

Outputs

RA4 LEARN mode active LED

RA5 VLOW LED

RC0 S0 Function LED

RC1 S1 Function LED

RC2 S2 Function LED

RC3 S3 Function LED

Network Transceiver

RA1 Chip Select output ICSP Clock

RC4 TX output

RC5 RX input

Note: When programming the module, remove Jumpers 1 and 2. Replace after verification.


Remote Keyless Entry Receiver-Decoder Module

4.2.5 Connectors

FIGURE 4-2: J1 SYSTEM CONNECTOR

FIGURE 4-3: J2 PROGRAMMING CONNECTOR

FIGURE 4-4: J3 POWER CONNECTOR

1

2

3

4

5

6

no connection

no connection

no connection

+12 VDC VBAT

LIN Bidirectional BUS

Chassis GND

123456

MCLR

VCC

ICSPDAT

no connection

VSS

ICSPCLK

+12 VDC VBATCHASSIS GND



FIGURE 4-5: SCHEMATIC – TRANSPONDER KEY FOB

LIN

bu

s

VC

C

VC

C VB

B

VC

C

VC

C

VB

B

VC

C

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S1

S3

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NC5

NC6

GND7

NC8

NC9

VCC10

GND11

VCC12

TEST13

OUT14

VCC15

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33

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E2

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1R

A1

/CIN

-1

2R

A0

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10

RC

4/C

2O

UT

6

RC

55

RC

37

RC

1/C

2IN

-9

RC

28

U2

PIC

16

F6

36

U2

PIC

16

F6

36

+C

2

10

uF

+C

2

10

R5

1K

R5

1K

J3

J3

Not assem

ble

d w

ith P

IC16F

636



4.3 SOFTWARE

The firmware is derived from Microchip Application Note AN743, “Modular PICmicro® Mid-Range MCU Code Hopping Decoder” (DS00743). Originally written for a PIC16CE624, the code has been ported to the PIC16F6XX family of devices.

The program implements a KEELOQ code hopping decoder. The software has been designed as a set of almost independent modules (standard assembly include files “*.INC”). For clarity and ease of maintenance, each module covers a single simple function and can be replaced to accommodate different behavior and/or support a different set of peripherals (memories, timers, etc.).

The set of modules presented in this application note implements the following features:

• Interrupt driven Radio Receiver (PWM) routine• Uses internal EEPROM memory to learn up to 16 transmitters• Supports Normal Learn mode• Compatible with all existing KEELOQ code hopping encoders with PWM

transmission format selected, operating in “medium mode” (Te = 200 μs)• Uses internal 8 MHz oscillator (self-calibrating during receive)

4.3.1 Modules Overview

The code presented in this application note is composed of the following basic modules:

The software has been modified to include four assemble-time conditional options.

Select Processor, enable only one below:

#DEFINE P12F635 1 ;Sets environment for PIC12F635#DEFINE P16F636 1 ;Sets environment for PIC16F636

Select PORTA push buttons to be connected to ground with internal pull-ups OR, connected to VCC with internal pull-downs:

#DEFINE pullup 1 ;Set to select pull-ups on PORT A.;For pull-downs, comment out

Since the In-Circuit-Emulator can not properly handle Sleep:

#DEFINE ICEmul 1 ;Is set, device will not SLEEP, but will;loop forever

Select option not to Encrypt:

#DEFINE NoEncryption 1

File Name Function

CHECKSN.ASM Substituted for KEELOQ® decryption files

FASTDEC.INC(1) KEELOQ® decryption routine

KEYGEN.INC(1) KEELOQ® decryption key generation routines implementing Normal mode

MEM-63X.INC Encapsulates PIC16F636 EEPROM drivers

MID.ASM The actual initialization and main loop

RXI.INC Interrupt driven receiver

TABLE.INC Transmitters table memory management (linear list)

Note 1: These files are not included in the general distribution set. They are available on the KEELOQ decoder license CD-ROM (DS40038) through your local Microchip Sales Office.



FIGURE 4-6: MODULES OVERVIEW DIAGRAM

TMR0

RXI.INC

1st Buffer X

BFFULL Flag

Radio Rec

Receive Buffer CSR

MID.ASM

Main Loop

Interrupt

Learn

Out S0

Out S3

LED

VLOW

KEY64.Inc

Manufacturer Code

KEYGEN.INC

- Normal KEY GEN- Manufacturer Code Load

CheckSN.asm(1)

TABLE.INC

- Insert- Search

MEM-62X.INC

- RD Word- WR Word

EEPROM

KEELOQ® decoder(1)

FL62X.ASM

FASTDEC.INC

- Decrypt

-OR-

Note 1: Substitute for KEELOQ decoder decryption files.



FIGURE 4-7: CODE WORD DATA FORMAT

FIGURE 4-8: CODE WORD DATA FORMAT, NO ENCRYPTION


CRC2 Bits

VLOW1Bit


C1 C0 S2 S1 S0 S3

BUT4 Bits

CounterOverflow

2 BitsDISC

10 Bits

Synchronization

16 BitsCounter

15 0

S1S2 S0 S3 OVR1 OVR0





BUT4 Bits


CRC2 Bits

VLOW1Bit


C1 C0 S2 S1 S0 S3

BUT4 Bits

S1S2 S0 S3




BUT4 Bits

Serial Number 2(16 Bits)USER1

4 BitsUSER08 Bits

Data 71h Data 72h



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10/31/05