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Application note AN-E005
“How to Implement ICP Using ELAN EM78PXXX
General Purpose OTP MCUs”
Technical Description, Release 1.0
© Copyright 2003 Elan Microelectronics Corporation, No. 12, innovation 1st. Rd. Science-Based Industrial Park, Hsinchu City,
Taiwan.
The use of this document is limited to:
1. Distribution within your organization.
2. Distribution to potential customers or partners.
This authorization is given on condition that any extract of these documents made by you shall retain all proprietary notice,
including this copyright notice.
The contents of this specification are subject to change without notice. Elan Microelectronics assumes no responsibility for
errors that may appear in this specification and makes no commitment to update, or to keep current, the information contained
in this specification. The products described herein are not intended for use in life support appliances, devices, or systems.
Use of Elan Microelectronics products in such applications is not supported and is prohibited.
NO PART OF THIS SPECIFICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS
WITHOUT THE EXPRESS WRITTEN PERMISSION OF ELAN MICROELECTRONICS.
Note that any product, process or technology described in the document may be subject of other intellectual property rights
reserved by Elan Microelectronics Corporation or a third party. No right to use such Intellectual Property Right is granted
hereunder.
Trademarks
Elan Microelectronics Corporation and the Elan logo are registered trademarks and service marks or trade names whether
registered or not, which may attach to certain words or signs used herein. The absence of such mention, however, in no way
implies that there is no protection.
Elan Microelectronics Corporation may make improvements or changes in the products or the program described in this
document at any time without notice.
This page and all content enclosed are © Copyright Elan Microelectronics, Hsinchu City, Taiwan.
REVISION HISTORY
Version
Date
Author
Description
1.0
24.06.2004
Mark Svoboda
Released
AN-E005-V1.0-page 2
Preliminary
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TABLE OF CONTENTS
1.0 INTRODUCTION
4
2.0 “RE-PROGRAMMING” AN OTP MICROCONTROLLER
4
3.0 ABOUT ELAN’S EM78P156
4
4.0 HOW TO IMPLEMENT ICP WITH EM78P156
4
5.0 APPLICATION CIRCUIT
5
6.0 PROGRAMMER
5
7.0 PROGRAMMING ENVIRONMENT
5
8.0 REPROGRAMMING WITH ELAN OTP MCU EM78P156
6
9.0 CONCLUSION
6
APPENDIX A:
PROGRAM EXAMPLE
7
APPENDIX B:
EXAMPLE ICP CIRCUIT
8
AN-E005-V1.0-page 3
Preliminary
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1.0 INTRODUCTION
In-circuit programming ICP is a technique that allows a programmable
device, a microcontroller for example, to be programmed after the
device has been placed or soldered in the circuit board. ICP is a great
way to reduce the cost of field firmware upgrades as well as reduce
time to market for your product. This solution also allows
manufacturers to quickly match microcontroller firmware variations
running on the same PCB with actual market demand via last-minute
programming.
This application note describes a simple way to program Elan’s family
of 8-bit general purpose microcontrollers while the IC is mounted in the
application PCB. For purposes of description, this application note
describes ICP for Elan’s popular EM78P156 1K ROM OTP
microcontroller while mounted in the PCB. The same technique may
also be used for Elan’s EM78P153, EM78P156N, EM78P257,
EM78P447(N), EM78P458, EM78P459, EM78P418N, EM78P419N,
and EM78P809N microcontrollers, all of which have very similar OTP
programming structures.
2.0 “RE-PROGRAMMING” AN OTP
MICROCONTROLLER
Although by definition OTP microcontrollers can only be programmed
one time, this ICP application note also describes a method by which
an OTP device can be re-programmed multiple times depending on the
size of the firmware as compared to the microcontroller OTP ROM
size.
3.0 ABOUT ELAN’S EM78P156
The EM78P156 is an 8-bit, high-speed RISC microcontroller with 57
instructions for general-purpose applications. It has 1K of OTP
program ROM, 48 bytes RAM, and 12 I/O pins. Operating voltage is
2.3 – 5.5V. It comes in 4 package variations, DIP, SOP, and SSOP
with 2 different pinning configurations:
Figure 1: EM78P156 package variation
The EM78P156 is pin and function compatible with Microchip PIC
16C54/55/56 (see Elan application note “Replacing Microchip’s PIC
16C54/55/56/57 with Elan Microelectronic’s EM78P156/P447”).
4.0 HOW TO IMPLEMENT ICP WITH
EM78P156
There are three main components of an ICP system: application circuit,
programmer, and programming environment.
AN-E005-V1.0-page 4
Preliminary
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5.0 APPLICATION CIRCUIT
See Appendix B: Example ICP circuit
For OTP programming, 6 dual-function pins of the microcontroller are
required for programming. They are:
Table 1: PIN assignment of EM78P156ELP/ELM
Pin Name
Pin
(programming mode #
/ operating mode)
I/O
Another important issue is supply voltage. The OTP
programming specification states that the MCU should be
programmed at 5V. If the application circuit’s operating
voltage is not 5V, the VDD pin should be isolated, and a 5V
supply applied to VDD.
Function during
programming mode
6.0 PROGRAMMER
ACLK / OSCO
15
I
DATAIN / P50
17
I/O
DINCK / P51
18
I
PGMB / OSCI
16
I
OEB / P67
13
I
VPP / RESET
4
I
CLK for address
increase
ROM series Input/Output
pin
The second consideration is the OTP programmer and its
drive capabilities. DWTR is ELAN’s standard OTP
programmer which has been designed to program the MCU
in a socket mounted on the programmer. It has not been
designed to drive signals over long connectors. It is therefore
recommended that the cable length between the
programmer and application circuit should not be longer than
20 centimeters. If the cable length is too long, the
programming might be fail due to signal attenuation.
CLK for DATAIN pin
Program enable control
pin, active low.
Output enable control for
DATAIN, active low for
output.
13 Volt for OTP
programming.
The application circuit must be designed to allow all the OTP
programming signals to be connected directly to the EM78P156. Fig. 1
shows an example circuit for implementing ICP with the EM78P156.
When designing an application circuit with ICP, several issues must be
considered:
Note: for manufacturers wanting to develop their own OTP
programming
hardware,
Elan’s
OTP
programming
specifications are available free of charge under NonDisclosure Agreement (NDA).
7.0 PROGRAMMING ENVIRONMENT
Isolation of all the programming signal pins from the
surrounding circuit.
Minimum and maximum operating voltage for VDD.
Different programming environments require different types
of programmer, and programming interface. You may
rd
choose Elan’s DWTR OTP programmer, a 3 party gang
writer, or develop your own ICP hardware.
In a typical application circuit, each pin of the MCU might be connected
to several other active and/or passive components. Any component
still connected to programming pins during programming could cause
an OTP programming error. For example, capacitive loading on a
programming signal pin could negatively affect the programming
signal’s required rise time. Resistive loading would reduce necessary
programming signal voltages. Therefore, the first step to implement the
ICP circuit is isolation of all the programming pins.
ICP application circuits may need customised connectors to
the programmer and to the application PCB, and the cable
distance between programmer and application circuit may
also affect the driver’s ability to provide the correct signals
and required current. The cables also need to be shielded to
prevent programming signals being corrupted by external
noise.
ƒ
ƒ
Fig. 1 shows the ICP circuit example. The critical factor in the ICP
circuit is how to isolate the 6 programming-related pins without
affecting the functionality of the application circuit. EM78P156 needs
six pins for OTP programming. All these programming pins need to be
isolated during programming. When the EM78P156 is programmed,
the /RESET/VPP pin must be supplied with an external 13V DC level.
The VPP pin of EM78P156 also functions as the reset pin during
normal operation, and is normally connected to an external RC circuit.
Therefore it is recommended to use a diode to isolate the VPP pin.
After take into consideration the application circuit, the
programmer, and the programmer environment, virtually
anyone can make a workable, high quality ICP application
circuit.
The CD4066 is a low-cost bi-directional solid-state electronic switch.
The circuit below is configured such that a high voltage (13V) applied
to VPP during OTP programming will cause the CD4066, via a
transistor inverter (2N3904), to disconnect the 6 other pins which are
used for OTP programming. After programming, to insure that the
application circuit functions normally, the resistor values must be
chosen such that the 2N3904 is switched off during normal operation
of the circuit. When designing your application, you should also
consider the ON state resistance of the CD4066 switch, which can
depend on the supply voltage.
Note that electrical isolation of pins may also be achieved by
mechanical jumpers, or mechanical switches. This method involves
manual intervention before and after ICP programming.
AN-E005-V1.0-page 5
Preliminary
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8.0 REPROGRAMMING WITH ELAN OTP
MCU EM78P156
By definition, OTP microcontrollers are not normally reprogrammable.
However, there is a method to reprogram Elan’s OTP MCU so long as
it is not write protected after the first programming, and there is enough
blank OTP memory remaining to accommodate your desired additional
firmware.
The EM78P156 has two vectors, reset and interrupt, at locations 0x00
and 0x08 respectively. When the EM78P156 encounters reset or an
interrupt occurs, the code location in one of these two addresses is
executed. Appendix A: Example 1 shows a sample of list files. The list
on the left-hand side in example 1 is the code first programmed into
EM78P156. The list on the right-hand side of example 1 is the
additional code programmed for the second time. From example 1, if
your OTP memory already has firmware programmed into it, and has
free remaining space in the OTP memory, which is large enough to
accommodate the additional desired code, you could program the
remaining blank OTP memory with the new code, and replace the
original code with NOPs.
First consideration is that you must reserve enough free memory
addresses after the rest/interrupt vectors because the location of the
jmp commands programmed in the corresponding reset and
9.0 CONCLUSION
Anyone can create a reliable ICP programming circuit by adopting the
recommended circuit design and programming techniques previously
mentioned.
Multiple-time OTP programming can also be achieved with the
software technique described in this application note.
Elan’s technical support staff are available to answer any questions
you have about the requirements for ICP based on Elan’s OTP
microcontrollers.
AN-E005-V1.0-page 6
Preliminary
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APPENDIX A:
PROGRAM EXAMPLE
Example1: Firmware list files
First
Program
Program
Memory
Opcode
00000
1410
00008
1409
00009
0000B
0000C
0000D
0000E
0000F
0080
004F
18FF
0046
0013
00010
00010
00011
00012
00013
00014
00015
00016
00017
00018
00019
0001A
0001B
0001B
184F
0002
0080
0005
0006
0046
1840
000E
1804
000F
0010
HERE:
141B
Assembly
Instruction
ORG
JMP
ORG
JMP
ORG
INTERRUPT:
CLRA
MOV
MOV
MOV
RETI
START:
MOV
CONTW
CLRA
IOW
IOW
MOV
MOV
IOW
MOV
IOW
ENI
JMP
0X00
START
0X08
INTERRUPT
0X0B
RF,A
A,@0XFF
PORT6,A
A,@0b01001111
PORT5
PORT6
PORT6,A
A,@0b01000000
0X0E
A,@0b00000100
0X0F
HERE
Second
Program
Program
Memory
Opcode
00000
0000
00001
1421
00008
0000
00009
141C
0000B
0000C
0000
0000
0000D
0000E
0000F
00010
00011
00012
00013
00014
00015
00016
00017
00018
00019
0001A
0001B
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0001C
AN-E005-V1.0-page 7
Assembly
Instruction
ORG
NOP
ORG
JMP
ORG
NOP
ORG
JMP
ORG
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
ORG
INTERRUPT:
0X01
START
0X08
0X09
INTERRUPT
0X0B
0X1C
0001D
0001E
0001F
00020
00021
00021
00022
00023
00024
00025
004F
18FF
0046
0013
00026
0046
MOV
PORT6,A
00027
1840
MOV
A,@0b01000000
00028
00029
0002A
000E
1804
000F
IOW
MOV
IOW
0X0E
A,@0b00000100
0X0F
0002B
0010
ENI
184F
0002
0080
0005
0006
Preliminary
MOV
MOV
MOV
RETI
START:
MOV
CONTW
CLRA
IOW
IOW
0X00
RF,A
A,@0XFF
PORT6,A
A,@0b01001111
PORT5
PORT6
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APPENDIX B:
EXAMPLE ICP CIRCUIT
VDD
R
C
CD4066
EM78P156
P51
I/O1_A
I/O1_B
I/O2_A
I/O2_B
I/O3_A
I/O3_B
I/O4_A
I/O4_B
I/O5_A
I/O5_B
P50
D
OSCI
/RESET/VPP
VSS
OSCO
VDD
P67
To application circuit
VDD
Control Pin
R
R
2N3904
ICP
ICPConnector
connector
AN-E005-V1.0-page 8
Preliminary
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