e01c086.PDF

MICRO PROCESSOR

ISAC (3)

part 3: the software development environment

By Prof. Dr. B. vom Berg, P. Groppe and M. Müller-Aulmann

In this third instalment in the series on the intelligent sensor/actuator con-

troller (or ISAC) we look at the software development environment for the

Analog Devices MicroConverter. Following on from the description of

the device in part 1 and the construction of a prototyping system in part 2

we are now in a position to write our ﬁrst program for the ISAC cube.

The Analog Devices MicroConverter can, in

principle, be programmed using any of the

familiar programming languages, including

Assembler51, Basic52, Pascal51, C51 and so

on. The result of the translation carried out by

the assembler or compiler is simply an Intel

Hex file, which must be downloaded, either

serially or in parallel, into the MicroCon-

verter’s Flash memory.

However, Analog Devices offers a com-

plete software development environment

optimised for use with the MicroConverter

family, freely downloadable from the Internet:

the ‘MicroConverter QuickStart Development

System V3.0’ [1]. This allows programs to be

developed in assembler or in C.

Also, a complete ‘QuickStart Development

Kit’ can be ordered from Analog Devices: this

contains, in addition to the development soft-

ware, an ADuC812 evaluation board (in Euro-

card format) with mains power supply, data

transfer cable and two ADuC812 chips. If you

plan to use the hardware described in the last

instalment of this series (ISAC cube plus pro-

totyping board), then alongside the software

development environment you can ﬁnd much

other information (data sheets, application

notes and so on), all freely downloadable from

the Internet. Table 1 and Table 2 give an

overview of the available software tools.

Assembly Source

Files

ASM51

8051 Assembler

ASM51

8051 Assembler

WSD

Windows Serial

Downloader

WASP

ADC Performance

Evaluation Tool

ADSIM

Windows Simulator

DEBUGV2

Windows Debugger

QuickStart

Development

System

User Target

Hardware Platform

010048 - 3 - 11

Figure 1. Developing MicroConverter programs in assembler.

– Develop and test programs in a

high-level language, i.e. in

BASIC52, Pascal51 or C51, of

which the last is now regarded

as the professionals’ choice in

industry.

The Intel Hex ﬁle generated with the

aid of the 8051 assembler can now

be loaded into a simulator

(adsim812) running under Windows.

This allows the complete behaviour

of the MicroConverter to be simu-

lated on the PC at assembler level,

including all the on-chip peripherals

(A/D, D/A converters and so on),

without the need to connect the

actual target hardware. Powerful

debugging facilities, such as setting

breakpoints, single-step execution,

Assembler51

The Assembler51 route is illustrated

in Figure 1 . Using an ordinary text

editor the assembler source file is

prepared in 8051 assembler code.

When developing programs for the Micro-

Converter there are two fundamentally dif-

ferent ways to proceed:

– Develop and test programs using the low-

level Assembler51 programming language.

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MICRO PROCESSOR

(sensors, an LC display, keyboard etc.), then

the ADuC Debugger can be used. This con-

nects directly to the development PC using

the ADuC812’s serial interface. The debug

results are taken directly from the actual

hardware, and the debugging commands are

sent directly to, and carried out by, the actual

hardware. Again, all the various test facilities

are of course available here: single-step exe-

cution, breakpoints, register loading and so

on. This tool is thus a hardware-based debug-

ger ( Figure 3 ).

In very many cases using the simulator

and the debugger will uncover all bugs and

problems in a program.

In summary, Assembler51, the software-

based simulator, and the hardware-based

debugger offer the user an ideal introduction

to assembler programming for the MicroCon-

verter family from both a hardware and soft-

ware point of view.

Figure 2. The software-based ADuC812 simulator.

C51

To develop MicroConverter programs in the

C51 high-level language Analog Devices have

made available a ‘trial’ version of the µVision

integrated development environment (IDE)

produced by Keil, limited to a maximum pro-

gram size of 2 kbyte. Keil is one of the world’s

leading producers of IDEs for all derivatives

of the 8051 microcontroller family [3]. The

µVision user has the great beneﬁt of gaining

familiarity with a very powerful professional

development tool, with, however, the small

concomitant disadvantage that gaining this

familiarity takes a little effort ( Figure 4 ).

To make the first steps easier, you can

download application note uC002 ‘Writing

an ADuC812 Application in C’ from the

MicroConverter homepage, and application

note apnt_151 ‘Using the Keil Monitor51

/µVision 2 Debugger with the Analog

Devices ADuC812 Evaluation Board’ from

the Keil Homepage ( www.keil.com ). There

data memory and so on are all

included in the set of commands.

This tool is a purely software-based

simulator and debugger, with the

whole of the ADuC812 laid out on

the PC’s screen ( Figure 2 ).

If, while simulating or debugging,

it is necessary to include the actual

target hardware, for example to

check the exact behaviour of exter-

nally-connected peripheral units

Table 1

The software development environment for the MicroConverter

Programming in a low-level language: Assembler51

MetaLink DOS-based 8051 cross assembler: asm51 (V1.2h).

Windows-based simulator for the ADuC812: adsim812.

Windows-based debugger for the ADuC812: ADuC (V2).

Programming in a high-level language: C51

Keil µVision Integrated Development Environment (IDE) (limited to 2 kbyte maxi-

mum program size).

Program downloader

Windows-based serial downloader for programming the on-chip Flash EEPROM

program memory from an Intel Hex ﬁle and for programming the Flash EEPROM

data memory on the device.

Table 2

Additional C tools for the

MicroConverter

Analysis Tools

Windows-based tool for analysis of data values obtained from the A/D converter

(including FFT analysis).

Commercial tools (trial versions):

Raisonance Rkit-51 ( www.raisonance.com )

IAR Embedded Workbench

ICC8051

Documentation

Getting Started — Introduction

User guides for the MicroConverter

Tool tutorials

Application notes / example code

Data sheets

Broad support via third-party tools

( www.iar.com )

Free tools:

Reads51 ( www.rigelcorp.com )

Small Device C Compiler – SDCC

(sdcc.sourceforge.net) for Windows and

Linux

12/2001

Elektor Electronics

MICRO PROCESSOR

you will find a very clear step-by-step expla-

nation of how to organise and compile your

first project in C51 under µVision, arriving at

a downloadable Intel Hex file as the final

result. This IDE also allows convenient sim-

ulation of your C program. Another reason

for downloading and working through these

application notes and installing µVision as

described is that we will be using C51 exclu-

sively in the following experiments in the

world of ADuC812 software.

As already indicated at the start, in addi-

tion to the tools described above any other

8051-family programming tools can be used

with the MicroConverter. A further selection of

tools for programming in the C language can

be found in Table 2 .

Serial Downloader

Now that you have created the ﬁnal Intel Hex

file (containing machine code for the

ADuC812), using either Assembler51 or C51

(or some other 8051 language), you must

transfer this program code file to the

ADuC812.

This can be done with the ADuC debug-

ger, or alternatively you can use the Win-

dows-based Serial Downloader from Analog

Devices, designed for the full range of Micro-

Converter products ( Figure 5 ).

This very important process of download-

ing the program is carried out in three key

steps ( Figure 6 ).

Figure 3. The hardware-based ADuC812 debugger.

On normal initialisation (when

power is applied or the reset but-

ton is pressed with PSEN not

being held low), this special mem-

ory area is disabled and invisible:

the ADuC812 ignores its contents

and runs the application program

from Flash EEPROM (normal oper-

ation). If, however, the ADuC812

detects a low level on PSEN when

the reset button is pressed or

released, it ignores the application

program in the Flash EEPROM

and switches instead to the secret

program memory and runs the

program stored there — the

Download or Debug routine —

thereby entering Download/Debug

mode.

Step 2. Now you can start the Serial

Downloader ( Figure 5 ). This pro-

gram automatically looks for a Micro-

Converter connected (in the first

instance) to COM1, and establishes

a connection with it. If the ADuC812

Step 1: The ADuC812 must ﬁrst be switched

into Downl oad/D ebug mode (Figure 6a). To

do this, the PSEN pin of the ADuC812 is taken

to ground vi a a 1 k W resistor (resulting in a

low level on PSEN) and then the reset button

is pressed. On the ISAC cube, hold down T2

(‘Boot’) and then press T1 (‘Reset’). Then

release T1 and then T2.

Explanation for 8051 experts:

a. On a ‘normal’ 8051 the PSEN pin is always

an output (read enable for program mem-

ory). On the MicroConverter, however,

PSEN becomes an input on reset (i.e., as the

reset button is released) and the level on the

pin is read. If PSEN is at a low logic level,

the ADuC812 switches immediately into

Download/Debug mode, which means that a

program to be downloaded can be received

over its serial port and the on-chip Flash

program memory can be programmed.

b. Each MicroConverter contains a ‘secret’

program memory in which the manufac-

turer has provided routines for serial pro-

gram download, for programming of the

Flash EEPROM, and to implement the

debugging functions as described above.

Figure 4. The µVision IDE.

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12/2001

MICRO PROCESSOR

is connected to a different COM

interface, the appropriate interface

can be chosen using the ‘Conﬁgura-

tion’ menu. Here also you can set

other parameters for the download.

Initially, leave the settings at their

default values. Next click on ‘Down-

load’ and select, in the usual Win-

dows way, the Intel Hex file to be

downloaded from the appropriate

directory. Downloading should then

proceed automatically and without

problems.

certainly enough: if you rewrite your

program 20 times a day, you can

carry on for a full 500 days! Things

are different, however, with the 640-

byte Flash EEPROM data memory,

where any desired data can be writ-

ten as often as required. In some

cases it is possible to reach or even

overstep the critical limit of 10,000

erase/write cycles very quickly,

especially when, for example, you

store frequently changing measured

values in these memory locations. In

such cases it is better to opt for

external expansion data memory in

the form of a RAM (how this can be

done will of course be explained

later). But even here Analog Devices

is developing its MicroConverter

product line further: later derivatives

(see Table 2 in the ﬁrst instalment of

this series) have a data retention of

up to 100 years(!) and are specified

for at least 100,000

Figure 5. The Serial Downloader.

Step 3. After the download proce-

dure is complete the Serial Down-

loader can be dismissed to the task

bar. Press the reset button (T1) on

the cube, and start your program

running on the ADuC812

( Figure 6b ). Recall that, since you

were not holding down T2, PSEN

will not be held low and the

ADuC812 does not execute from its

hidden internal program memory.

developing an enhanced version of the devel-

opment tools for the MicroConverter, and so

it is worth keeping an eye on the MicroCon-

verter homepage ( www.analog.com/

microconverter ), to obtain the most up-to-

date information.

erase/write

(010048-3)

cycles.

Literature and websites:

[1] MicroConverter Internet homepage:

www.analog.com/microconverter

[2] Analog Devices on the Internet:

www.analog.com

[3] Keil µVision IDE: www.keil.com

Each fresh download proceeds

always from step 1 again: hold

down T2, press T1, release T1,

release T1, start the Serial Down-

loader, and so on.

Emulators

Finally we should note that there are

emulators available for the Micro-

Converter. MetaLink

( www.metaice.com ) produces a clas-

sical emulator for the ADuC812: that

is, one which replaces the Micro-

Converter in its socket in the target

system.

Accutron ( www.accutron.com )

produces the ACE ‘single pin emula-

tor’, which supports all derivatives

in the MicroConverter family and

which includes C source-level

debugging. The emulator is con-

nected to the target system via the

EA pin. Like the PSEN pin, this pin

has many uses, which are described

in the data sheet and in the Micro-

Converter ‘User’s Manual’. In regard

to MicroConverter derivatives with

16- and 24-bit analogue-to-digital

converters in particular, this type of

connection with the target system is

of course very simple and has many

advantages. This puts a powerful

development tool at the disposal of

the professional user.

Once you have learnt how to use

the full range of tools to turn your

ISAC cube programming ideas into

reality, we can proceed in the next

instalment to a few suggestions for

interesting applications written in

C51. Meanwhile, Analog Devices is

Best before date

The Flash EEPROM on the ADuC812

is a non-volatile memory, which

means that it retains its contents

even in the absence of a power sup-

ply — but not forever. Also, there is

a limit to how many times fresh pro-

grams can be downloaded.

Analog Devices provides the fol-

lowing information on this point in

the ADuC812 data sheet:

ADuC812

RESET

PSEN

010048 - 3 - 16a

– Data are retained in the Flash

memory (with or without power

supply) for at least 10 years; after

that there may be ‘drop-outs’

which manifest themselves as

errors in the stored data.

– The maximum number of repro-

gramming cycles (erase and

rewrite of memory locations before

errors occur in the memory) is

given as 10,000.

Figure 6a. Activation of debug/program down-

load mode.

ADuC812

RESET

PSEN

It is worth noting that in each

ADuC812 there are two separate

regions of Flash memory available.

For the program memory the

10,000 reprogramming cycles are

010048 - 3 - 16b

Figure 6b. Normal operating mode.

12/2001

Elektor Electronics

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