Ds 21986 a

© 2006 Microchip Technology Inc. DS21986A
Passive Keyless Entry (PKE)
Reference Design
User’s Manual

DS21986A-page ii © 2006 Microchip Technology Inc.
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• 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
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PKE REFERENCE DESIGN
USER’S MANUAL
© 2006 Microchip Technology Inc. DS21986A-page iii
Table of Contents
Preface ........................................................................................................................... 1
Chapter 1. System Overview
1.1 Overview ........................................................................................................ 6
1.2 Operational Overview ..................................................................................... 7
1.3 Features ......................................................................................................... 7
1.3.1 LF Initiator ................................................................................................... 7
1.3.2 Key Fob ....................................................................................................... 7
1.3.3 RF Receiver ................................................................................................ 8
1.4 Reference Documents .................................................................................... 8
Chapter 2. Low-Frequency Initiator Module
2.1 Introduction ................................................................................................... 10
2.2 Hardware ...................................................................................................... 10
2.2.1 Microcontroller ........................................................................................... 10
2.2.2 Configurable Inputs ................................................................................... 10
2.2.3 LF Transmitter ........................................................................................... 10
2.2.4 Network Interfaces .................................................................................... 10
2.2.5 Power ........................................................................................................ 10
2.3 Software ....................................................................................................... 12
Chapter 3. PKE Transmitter-Transponder
3.1 Introduction ................................................................................................... 14
3.2 Hardware ...................................................................................................... 14
3.2.1 Transmitter ................................................................................................ 15
3.3 Software ....................................................................................................... 17
3.3.1 Dual Encoder Operation ............................................................................ 20
3.3.2 Code Hopping Code Word Data Format ................................................... 20
3.3.3 EEPROM Organization ............................................................................. 23
Chapter 4. Remote Keyless Entry Receiver-Decoder Module
4.1 Introduction ................................................................................................... 26
4.2 Hardware ...................................................................................................... 26
4.2.1 UHF Receiver ............................................................................................ 26
4.2.2 Microcontroller ........................................................................................... 26
4.2.3 Network Interface ...................................................................................... 27
4.2.4 Power Supply ............................................................................................ 27
4.2.5 Connectors ................................................................................................ 28
4.3 Software ....................................................................................................... 30
4.3.1 Modules Overview ..................................................................................... 30
Worldwide Sales and Service .................................................................................... 33

PKE Reference Design User’s Manual
DS21986A-page iv © 2006 Microchip Technology Inc.
NOTES:

USER’S MANUAL
© 2006 Microchip Technology Inc. DS21986A-page 1
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.

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 code
Filenames and paths
#define START
c: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

DS21986A-page 3 © 2006 Microchip Technology Inc.
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.

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:

USER’S MANUAL
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
LF
Initiator
Trigger
KEY
FOB
3-Axis
RF
Transmitter
Encoder
RKE
Receiver
AFE
RF
Receiver
Decoder
Drivers
Buttons
On-Vehicle
LIN Lock
Actuator
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 Code
Hopping 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:

USER’S MANUAL
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
PWM
PWM
V
CC
V
CC
V
CC
V
CC
+12
V
DC
V
CC
V
CC
+12
V
DC
V
CC
+12
V
DC
400V
P3476-ND
R6
15K
R6
15K
R10
120
R10
120
L2
DO5022P
L2
DO5022P
D3
1N5819
D3
1N5819
C7
0.1
uF
C7
0.1
Y1
20.0
MHz
Y1
20.0
R5
1K
R5
1K
D5
1N5819
D5
1N5819
D8
10MQ100N
D8
10MQ100N
D7
10MQ100N
D7
10MQ100N
D2
1N5819
D2
1N5819
CANH
7
GND
2
CANL
6
V
CC
3
TXD
1
RXD
4
REF
5
RS
8
U2
MCP2551
U2
MCP2551
C8
10
nF
C8
10
LED2
YEL
LED2
YEL
D4
1N5819
D4
1N5819
J1
J1
R8
4.7K
R8
4.7K
C4
20
pF
C4
20
C5
1.0
uF
C5
1.0
C9
0.200LS
C9
0.200LS
D6
1N4148
D6
1N4148
1
3
5
2
4
6
J4
CON6A
J4
CON6A
C3
20
pF
C3
20
C10
0.200LS
C10
0.200LS
MCLR
1
V
CC
2
GND
3
RB7
4
RB6
5
RB3
6
J2
RJ11
J2
RJ11
IN
1
OUT
3
GND
2
VR1
LM2937ET-5.0
VR1
LM2937ET-5.0
C6
1.0
uF
C6
1.0
1
TP1
TP1
R7
30K
R7
30K
R2
25K
R2
25K
R1
1K
R1
1K
1
3
5
2
4
6
J3
CON6A
J3
CON6A
MCLR/V
PP
1
OSC1/CLKIN
9
OSC2/CLKOUT
10
RA0/AN0
2
RA1/AN1
3
RA2/AN2/V
REF
-
4
RA3/AN3/V
REF
+
5
RA4/T0CLI
6
RA5/AN4/SS/LVDIN
7
RB0/INT0
21
RB1/INT1
22
RB2/CANTX
23
RB3/CANRX
24
RB4
25
RB5
26
RB6
27
RB7
28
RC0/T1OSO/T1CKI
11
RC1/T1OSI
12
RC2/CCP1
13
RC3/SCK/SCL
14
RC4/SDI/SDA
15
RC5/SDO
16
RC6/TX/CK
17
RC7/RX/DT
18
U1
PIC18F2680
U1
PIC18F2680
C1
10
μF
C1
10
R4
25K
R4
25K
3
V
D
D
6 V
D
D
2
GND
4
GND
5
OUT
IN
1
U4
TC4422
U4
TC4422
D1
10MQ100N
D1
10MQ100N
D9
1N4750
D9
1N4750
L1
10-00189
L1
10-00189
LIN
6
RX
1
TX
4
CS/WAKE
2
GND
5
V
BAT
7
V
D
D
3
FAULT/SLPS
8
MCP201
U3
MCP201
U3
R3
15K
R3
15K
LED1
GRN
LED1
GRN
C2
10
μF
C2
10
R9
1K
R9
1K
High
Voltage
These
two
input
circuits
are
set-up
for
+12-to-GND
signals.
To
input
a
+5-to-0
signal,
remove
R3
or
R6,
replace
R2
or
R4
with
1K,
and
either
put
a
10K
resistor
across
D2-D4
OR
enable
internal
pull-ups
in
the
microcontroller.

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 ms
Guard Time
LOGIC ‘0’
LOGIC ‘1’
Bit
Period

NOTES:

USER’S MANUAL
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.
1
2
3
4
5
6
MCLR
VCC
ICSPDAT
no connection
VSS
ICSPCLK

PKE Transmitter-Transponder
FIGURE 3-2: SCHEMATIC – RF RECEIVER/DECODER USING THE PIC16F639
CSn
ICSPCLK
LFDATA
ICSPDAT
LCCOM
LX
LY
PWM
SCLK/ALERT
LZ
V
CC
V
CC
V
CC
V
CC
V
CC
V
BAT
V
BAT
V
CC
V
CC
Unlock
Lock
Shift
Hazard
Boot
Active
Challenge
Do
not
assemble
parts
within
dotted
boxes
for
RKE-only
application.
Replace
PIC16F639
with
PIC16F636.
240
pF
+
24
pF
220
R3
220
R3
220
pF
CZ1
220
CZ1
3V/6V
BT1
3V/6V
BT1
C12
1.0
uF
C12
1.0
SW2
SW2
7.1
mH
LY1
7.1
LY1
10M
R9
10M
R9
C6
100
nF
C6
100
R16
100k
R16
100k
NE94433
Q1
NE94433
Q1
D8
1N4148WS
D8
1N4148WS
9.0
mH
LX2
9.0
LX2
R12
1K
R12
1K
100
nF
C4
100
C4
SW5
SW5
5.1V
D2
5.1V
D2
4
GND
8
GND
2
IN
1
nc
3
nc
5
nc
7
nc
6
OUT
433.92
U2
433.92
MHz
SAW
U2
470
R20
470
R20
264
pF
CX1
264
CX1
1.0
uF
C5
1.0
C5
12
pF
C3
12
C3
LED-RED
D4
LED-RED
D4
0
R8
0
R8
LED-GRN
D5
LED-GRN
D5
47K
R2
47K
R2
1.0
uF
C11
1.0
C11
SW1
SW1
470
R19
470
R19
47
R1
47
R1
SW3
SW3
SW4
SW4
7.1
mH
LZ1
7.1
LZ1
MA2S784
D1
MA2S784
D1
220
pF
CY1
220
CY1
+
1
+
3
+
5
+
2
+
4
+
6
J1
J1
Antenna
L1
Antenna
L1
470
pF
C1
470
C1
RA0/C1IN+
19
RA1/C1IN-
18
RA2/C1OUT/INT
17
RA3/MCLR
4
RA4/OSC2
3
RA5/OSC1
2
V
DDT
8
LCX
11
LCY
10
LCZ
9
LCCOM
12
RC0/C2IN+
16
RC1/C2IN-
15
RC2
14
RC3
7
RC4/C2OUT
6
RC5
5
V
SST
13
V
CC
1
GND
20
U3
PIC16F639
U3
PIC16F639
2.0
pF
C2
2.0
C2

3.3 SOFTWARE
The 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
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?
No
Buttons?
Seed
Time?
Read Seed
Stop
Yes
Yes
No
Yes
No
No
Yes
Yes
Yes Seed
Button?
No
New
Buttons?
No
LF
No
Yes
Data?
Receive
Valid
No
Yes
Request?
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)
CRC
2 Bits
VLOW
1 Bit
Serial Number
(28 Bits)
C1 C0 S2 S1 S0 S3
BUT
4 Bits
Counter
Overflow
2 Bits
DISC
10 Bits
Synchronization
16 Bits
Counter
15 0
S1
S2 S0 S3 OVR1 OVR0
Hopping Code Portion (32 Bits)
With XSER = 0, 16-bit Counter, QUEN = 0
Status Information
(3 Bits)
BUT
4 Bits
QUE
2 Bits
CRC
2 Bits
VLOW
1 Bit
Serial Number
(32 Bits)
Q1 Q0 C1 C0
BUT
4 Bits
Counter
Overflow
2 Bits
DISC
10 Bits
Synchronization
16 Bits
Counter
15 0
S2 S1 S0 S3 OVR1 OVR0
Status Information
(5 Bits)
QUE
2 Bits
CRC
2 Bits
VLOW
1 Bit
Serial Number
(28 Bits)
Q1 Q0 C1 C0 S2 S1 S0 S3
BUT
4 Bits
DISC
8 Bits
Synchronization
20 Bits
Counter
19 0
S2 S1 S0 S3
Status Information
(5 Bits)
BUT
4 Bits
CRC
2 Bits
VLOW
1 Bit
Serial Number
(32 Bits)
C1 C0
BUT
4 Bits
DISC
8 Bits
Synchronization
20 Bits
Counter
19 0
S2 S1 S0 S3
Status Information
(3 Bits)

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.
CRC
2 Bits
VLOW
1 Bit
Serial Number 1
(28 Bits)
C1 C0 S2 S1 S0 S3
BUT
4 Bits
S1
S2 S0 S3
With XSER = 0, 16-bit Counter, QUEN = 0, S<3:0> not equal ‘0111’
Status Information
(3 Bits)
BUT
4 Bits
Serial Number 2
(16 Bits)
QUE
2 Bits
CRC
2 Bits
VLOW
1 Bit
Serial Number
(32 Bits)
Q1 Q0 C1 C0
BUT
4 Bits
S2 S1 S0 S3
Status Information
(5 Bits)
USER1
4 Bits
USER0
8 Bits
Data 71h Data 72h
Serial Number 2
(16 Bits)
USER1
4 Bits
USER0
8 Bits
Data 71h Data 72h
CRC
2 Bits
VLOW
1 Bit
Serial Number 1
(28 Bits)
C1 C0 S2 S1 S0 S3
BUT
4 Bits
S1
S2 S0 S3
With XSER = 0, 16-bit Counter, QUEN = 0, S<3:0> equal ‘0111’
Status Information
(3 Bits)
BUT
4 Bits
Serial Number 2
(32 Bits)
QUE
2 Bits
CRC
2 Bits
VLOW
1 Bit
Serial Number
(32 Bits)
Q1 Q0 C1 C0
BUT
4 Bits
S2 S1 S0 S3
With XSER = 1, 16-bit Counter, QUEN = 1, S<3:0> equal ‘0111’
Status Information
(5 Bits)
Serial Number 2
(32 Bits)

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)
Symbol
Address
(Bits)
Description(1)
KEY1 1E: 64 bits Encoder Key
SEED1 14: 60 bits Encoder Seed Value
SYNC1 00: 20 bits
00: 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 Modulation
Format
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)
Symbol
Address
(Bits)
Description(1)
KEY2 34: 64 bits Encoder Key
SEED2 2A: 60 bits Encoder Seed Value
SYNC2 08: 20 bits
08: 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 Modulation
Format
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

TABLE 3-5: DEVICE OPTIONS
Symbol
Address
(Bits)
Description(1)
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
2: Voltage thresholds are ±100 mV.

USER’S MANUAL
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.
DataIN
Radio Rec.
Microcontroller
LEARN SW
Function LEDS
Transceiver
Bus
Network
LEARN LED
VLOW 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
1
2
3
4
5
6
MCLR
VCC
ICSPDAT
no connection
VSS
ICSPCLK
+12 VDC VBAT
CHASSIS GND

FIGURE 4-5: SCHEMATIC – TRANSPONDER KEY FOB
LINbus
V
CC
V
CC
V
BB
V
CC
V
CC
V
BB
V
CC
S0
S1
S3
S2
VLOW
LEARN
ON
Can
be
replaced
with
PIC16F688
for
LIN
applications
Can
be
replaced
with
MCP202
or
-315
C4
.01
uF
C4
.01
R4
1K
R4
1K
DS4
LED
DS4
LED
R3
1K
R3
1K
+
C1
10
uF
+
C1
10
R8
1K
R8
1K
DS3
LED
DS3
LED
R1
1K
R1
1K
R6
1K
R6
1K
R2
10K
R2
10K
D1
1N4004
D1
1N4004
LIN
6
RX
1
TX
4
CS/WAKE
2
GND
5
V
BAT
7
V
D
D
3
FAULT/SLPS
8
MCP201
U3
MCP201
U3
ANT1
ANT1
S1
S1
+
1
+
3
+
5
+
2
+
4
+
6
J1
J1
R7
1K
R7
1K
D2
1N4755
43V
D2
1N4755
43V
+
C3
0.1
uF
+
C3
0.1
R10
100K
R10
100K
1
2
3
4
5
6
J2
J2
C6
220
pF
C6
220
DS2
LED
DS2
LED
1 2
E1
E1
DS6
LED
DS6
LED
DS1
LED
DS1
LED
D3
1N4750
27V
D3
1N4750
27V
R9
1K
R9
1K
LED1
Green
LED
LED1
Green
LED
C5
1.0
C5
1.0
IN
1
OUT
3
GND 2
REG1
LM2937IMP-5.0
REG1
LM2937IMP-5.0
V
C
C
1
GND
2
ANT
3
NC
4
NC
5
NC
6
GND
7
NC
8
NC
9
V
C
C
10
GND
11
V
C
C
12
TEST
13
OUT
14
V
C
C
15
U1
AMRRS3-433
U1
AMRRS3-433
1 2
E2
E2
DS5
LED
DS5
LED
RA5/OSC1
2
RA4/OSC2
3
RA3/MCLR
4
RA2/C1OUT/INT
11
RA1/CIN-
12
RA0/CIN+
13
RC0/C2IN+
10
RC4/C2OUT
6
RC5
5
RC3
7
RC1/C2IN-
9
RC2
8
U2
PIC16F636
U2
PIC16F636
+
C2
10
uF
+
C2
10
R5
1K
R5
1K
J3
J3
Not
assembled
with
PIC16F636

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:
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
CRC
2 Bits
VLOW
1Bit
Serial Number
(28 Bits)
C1 C0 S2 S1 S0 S3
BUT
4 Bits
Counter
Overflow
2 Bits
DISC
10 Bits
Synchronization
16 Bits
Counter
15 0
S1
S2 S0 S3 OVR1 OVR0
Status Information
(3 Bits)
BUT
4 Bits
CRC
2 Bits
VLOW
1Bit
Serial Number 1
(28 Bits)
C1 C0 S2 S1 S0 S3
BUT
4 Bits
S1
S2 S0 S3
Status Information
(3 Bits)
BUT
4 Bits
Serial Number 2
(16 Bits)
USER1
4 Bits
USER0
8 Bits
Data 71h Data 72h

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10/31/05

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