Elektor_ ATMEL_AVR_Micro_Programmer_2001.pdf

MICRO PROCESSOR

Atmel AVR Micro

for 89Cx051 with up to 4k of program memory

Design by A. Oyrer

This programmer is suitable for programming the three popular 20-pin

Atmel processors, the 89C1051, 89C2051 and the new 89C4051 with

4 k of program memory.

There is a new arrival in the Atmel family of

powerful yet inexpensive MCS51-compatible

microcontrollers with ﬂash memory (PEROM):

the 89C4051 boasts 4 kBytes of program

memory. Besides the program memory capac-

ity all members of the family have

the following features:

– 128 bytes RAM

– 15 I/O port bits

– 2 16-bit timer/counters

– Interrupt architecture with two

priorities and ﬁve vectors

– Programmable full-duplex serial

port

– Precision analogue comparator

Elektor Electronics

9/2001

Programmer

MICRO PROCESSOR

– Integrated clock/oscillator circuit

Flash memory pr ogr amming modes

Modus

The AT89Cx051 family operates at

a clock frequency between 0 (sta-

tic) and 24 MHz and features two

software-selectable power-saving

modes: Idle (CPU only stopped)

and Power down (RAM contents

are preserved, but all functions are

disabled).

RST/VPP P3.2/PROG

P3.3 P3.4 P3.5 P3.7

Write program data 12 V

1.2 ms negative-going pulse L

Read program data

Write lockbit 1

12 V

1.2 ms negative-going pulse H

Write lockbit 2

12 V

1.2 ms negative-going pulse H

Erase memory

12 V

10 ms negative-going pulse

Read signature bits

Programming the ﬂash

The programming characteristics of

the flash memory are of course cru-

cial to the design of a programmer.

When the Atmel microcontroller

leaves the factory the program mem-

ory array is filled with FFs and is

ready to be written, byte by byte.

Once the array is programmed, a

byte that has been written can only

be rewritten after first erasing the

entire memory. The AT89Cx051

includes a PEROM address counter ,

which is reset to 00H on a positive-

going edge of RST and incremented

on each clock pulse on XTAL1.

The logical values on port pins P3.1

to P3.7 determine the programming

mode, as shown in Table 1 .

In order to write a program into

the PEROM, Atmel recommends the

following programming algorithm .

PORT 1

DATA IN

DATA OUT

P3.2

(PROG)

10 µ s

1 ... 110

RST

(V PP )

V PP

LOGIC1

LOGIC0

1 µ s

P3.4

(ENABLE)

50ns

P3.1

(RDY/BSY)

XTAL1

(INCREMENT

ADDRESS)

BUSY

READY

2 00n s

2ms

1 µ s

010005 - 12

Figure 1.Timing diagram for a write/read cycle.

7. To read data, the voltage on RST

is taken down to a normal logic

high level and port pins P3.3 are

set to the appropriate levels. The

byte stored in the current address

appears on port P1.

begin a new cycle before the end of the pre-

vious one, pin P3.1 is taken low (BUSY) for a

maximum of 2 ms, while writing is taking

place. Only when P3.1 returns high (READY)

can a new write cycle be initiated.

As can be seen from the timing diagram,

veriﬁcation of the write process can be car-

ried out either byte by byte during the BUSY

period during write (compare) or all in one go,

as long as the lock bits have not been set

(read). The latter is carried out as follows:

1. Power up by applying the supply

voltage to VCC and GND, and

hold RST/VPP and XTAL1 to

ground.

8. When the byte has been written

or read, the address counter is

incremented by a rising edge on

XTAL1. The new byte is put on

P1.

2. Take RST/VPP and P3.2 high.

3. Set port pins P3.3 through P3.7

according to the table.

1. Take RST from low to high to reset the

internal address counter to 000H.

9. Steps 5 to 8 are repeated until the

whole memory is programmed or

until the end of the programming

data is reached.

To write and read programming data

the next steps are as follows:

2. Set up the appropriate control signals on

pins P3.3 through P3.7 and the data byte

appears on P1.

4. Apply the first byte to be pro-

grammed (into memory address

00H) to pins P1.0 through P1.7.

10.To finish the programming

process, set XTAL1 and RST low

and remove the supply voltage

from VCC and GND.

3. Apply a pulse to XTAL1 to increment the

address counter by one place, and the

next data byte appears on P1.

5. Take RST to 12 V to being the pro-

gramming process.

6. Apply a negative-going pulse,

with a duration of between 1 and

100 µs, to P3.2 in order to write

the byte into the PEROM array or

into the lock bits. The write cycle

completes automatically after

about 1.2 ms.

A complete write/read cycle is illus-

trated in Figure 1 . P ort pin P3.1,

which signals READY/BUSY , is not

shown. The data sheet gives the

duration of the programming pulse

at between 1 and 100 µs. Since a

programming cycle lasts about

1.2 ms and it is not permitted to

4. Repeat step 3 until the entire memory is

read.

The lock bits cannot be directly verified,

but they can be identified by the effect they

produce.

The entire memory, along with the lock bits,

9/2001

Elektor Electronics

MICRO PROCESSOR

JP1

+5V

C13

C14

IC3

100n

10µ

63V

BC557B

C12

100n

AD0

AD1

AD2

AD3

AD4

AD5

AD6

AD7

R14

IC3

1N4148

+5V

D 6

RST

IC1

AD0

AD1

AD2

AD3

AD4

AD5

AD6

AD7

AD0

AD1

AD2

AD3

AD4

AD5

AD6

AD7

AD3

P10/IN+

P11/IN–

RXD/P30

TXD/P31

AD2

AD1

P12

P13

P14

P15

P16

P17

INT0/P32

INT1/P33

AD0

T0/P34

T1/P35

89C2051

AD4

P37

8x 10k

74HC373

IC6

R13

1k5

+5V

LM317

BC557B

R12

1k5

22p

11,059MHz

10µ

63V

+5V

R15

R10

V+

C1+

R11

C11

IC4

10µ

63V

C1–

BS170

1µ

25V

4V7

500mW

T1OUT

T2OUT

T1IN

T2IN

R1IN

R2IN

R1OUT

R2OUT

IC5

C2+

7805

+5V

18V

MAX232

10µ

63V

10µ

63V

C2–

1N4001

V-

C10

DB9

10µ

63V

10µ

63V

10µ

63V

010005 - 11

Figure 2. Circuit diagram of the Atmel Programmer with master controller and ZIF socket for the device to be programmed.

is electrically erased when the correct com-

bination is applied to P3.3-P3.7, and P3.2 is

held low for at least 10 ms. All memory loca-

tions are then filled with ones. This chip

erase procedure is required before repro-

gramming an already-programmed memory

or in order to erase the lock bits.

The signature bytes give manufacturer

and device type information. They can be

read in the same way as the program mem-

ory locations, but with P3.5 and P3.7 held low.

Possible values are as follows:

Programmer hardware

– Program lock bits

– Erase

– Read signature

Since, apart from the size of the pro-

gram memory, all the functions and

features of the three microcontrollers

are identical, the programmer is not

complicated. It must simply read the

signature bytes at the start of any

operation to identify the type of

microcontroller.

The programmer presented here

implements all the programming

modes described:

In write mode the signature bytes

are checked to ensure that the

amount of data to be programmed

will fit in the processor. In read

mode, the data ﬁle generated can be

in Intel Hex or in binary format.

Reading the signature bytes is

optional and can if required (for

example in the case of a faulty micro-

controller) be disabled via the menu.

In this case the programmer

assumes that it is dealing with an

89C4051.

000H 1EH: manufacturer code for Atmel

001H 11H: 89C1051

21H: 89C2051

41H: 89C4051

– Write

– Read

– Compare

Elektor Electronics

9/2001

MICRO PROCESSOR

As can be seen from Figure 2 , the

programmer hardware is relatively

straightforward and consists essen-

tially of a master microcontroller,

which needs to contain just 865

bytes of program code. IC1, naturally

enough an 89C2051, carries out

everything required for program-

ming: it sets up the programming

mode requested by the user, con-

verts into parallel form the program

code sent from the PC over the

RS232 interface, sends the contents

of an already-programmed memory

(and other information) back to the

PC, and switches the voltages (0 V,

5 V and 12 V) as required by the tim-

ing diagrams. However, even with

the best will in the world, all this is

not so easy to achieve with just the

15 I/O port bits offered by the

89C2051.

Communication with the PC is

handled via port pins P3.0 and P3.1.

Data transfer is indicated by LEDs

D4 and D5 flashing. Port pin P3.3

(interrupt 1) is used as an input to

monitor the BUSY/READY signal of

the microcontroller being pro-

grammed (‘processor under pro-

gramming’, or PUP). The individual

programming pulses are provided by

a further port pin, P3.5, while P3.4 is

used to provide the edges on XTAL1

to increment the address counter of

the PUP.

Now, the remaining ten port pins

must provide ﬁve control signals and

eight data bits, and here some inge-

nuity is required. The whole of port

1 of IC1 is connected to its counter-

part on the PUP, but the five port

pins P1.0-P1.4 are also connected to

IC3, an 8-bit latch type 74HC373.

The microcontroller ﬁrst applies the

control signals to the five latch

inputs. The latch enable input (pin

11) is taken high and so the latches

are transparent: control signal out-

puts AD1, AD2, AD3 go directly to

the PUP (as can be seen from

Table 1, P3.5 and P3.7 always have

the same value), AD0 turns on the

+5 V supply to the microcontroller

via T1 (indicated by LED D6), and

AD4 controls the application of the

programming voltage to RST/VPP.

Once these values are set up, the

latch enable input is taken low

again, and the values are stored.

The Atmel programmer uses an

adjustable voltage regulator to pro-

vide the voltage on RST/VPP. For

reading, when 5 V is required, FET

T2 conducts and the two resistors R6

and R8 are effectively in parallel. If

12 V is required, the FET is turned

off and only R8 is in circuit. The

BS170 is switched by a separate port pin of

IC1, P3.7.

In order that the voltage on VPP/RST is at

ground potential after the programming or

reading process (and so the PUP can safely

be removed from its socket) the LM317 is ﬁrst

switched to 5 V. Then AD4 (from the latch) is

set, to make the potential at the junction of

R10 and D3 equal to 5 V. This turns off tran-

sistor T3 and R11 pulls RST/VPP to ground.

This accounts for all the port pins of the

89Cx051.

Software

The companion diskette for this project, order

code 010005-11 , which is available from

Readers’ Services, includes an assembler pro-

gram called Atmelpr.asm for the master

microcontroller, as well as the microcontroller

object code in the form of a Atmelpr.hex ﬁle.

Ready-programmed microcontrollers are also

available (order code 010005-41 ). This soft-

ware is complemented by

Programmer_eng.exe ,

a program written in Delphi which controls all

the operations of the Atmel programmer such

as reading, writing, and erasing. The Delphi

source code source_eng.zip is also available.

The printed circuit board layout is avail-

able for free download from our Internet site

www.elektor-electronics.co.uk . There is no

download for the above mentioned software

because of contractual agreements with the

authors.

Serial port COM2 is used by default. When

the program starts up a window appears,

divided into two ( Figure 3 ). On the left the

operations are selected from a menu while on

the right the operations are confirmed, for

example as follows:

reading signature byte ok

programming lock bit 1 ok

error: ﬁle too large!

and so on.

Figure 3. Control panel for the PC program Programmer_eng.exe.

If Read is selected, all other operations are

disabled and a window appears to allow the

user to choose the name of the file in which

the contents of the processor’s memory are to

be written out. If the ﬁle extension is given as

hex , then an Intel Hex file is automatically

generated; if bin is speciﬁed, a binary ﬁle is

read.

The Select file button allows the user to

choose the name of the ﬁle that will be writ-

ten. Here also hex and bin are possible.

The ﬁle size is shown below the microcon-

troller type. Below that a bar indicates

progress of the individual actions. In the area

9/2001

Elektor Electronics

MICRO PROCESSOR

010005-1

C13

COMPONENTS LIST

IC5

IC6

C11

Resistors:

R1 = 8k

R2 = 100 Ω

R3 = 8-way 10k

C9 C10

Ω

SIL array

C14

R4,R5 = 1k Ω

R6 = 1210

C12

Ω

R7 = 274 Ω

R8 = 2260

JP1

R12

R13

Ω

R9,R10 = 10k Ω

R11 = 4k

R12,R13,R14 = 1k Ω 5

R15 = 2k

C2 C3

Ω

IC4

IC1

IC3

Capacitors:

C1,C4-C10 = 10

F 63V radial

C2,C3 = 22pF

C11 = 1

C7 C8

F 25V radial

C12,C13,C14 = 100nF

Semiconductors:

D1 = 1N4148

D2 = 1N4001

D3 = zener diode 4V7, 500 mW

D4,D5,D6 = LED, green, high effi-

ciency

T1,T3 = BC557B

T2 = BS170

IC1 = AT89C2051-12PC (order

code 010005-41 )*

IC2 (K3) = 24-way zero-insertion

force (ZIF) socket

IC3 = 74HC373

IC4 = MAX232

IC5 = 7805

IC6 = LM317T

Miscellaneous:

JP1 = jumper

K1 = 9-way Sub-D socket

(female), PCB mount, angled pins

K2 = mains adaptor socket

X1 = 11.0592MHz quartz crystal

Enclosure, size 137x

95x

⋅

* (see Readers Services page or

www.elektor-electronics.co.uk )

010005

at the bottom the ﬁlename and path

are shown.

In the menu under Read signature

byte the user can choose whether

the signature bytes are initially read

or not. This option should always be

activated unless the programmer is

unable to read the signature bytes.

The information in the signature

bytes is shown below the microcon-

Figure 4. Layout and component mounting plan for the double-sided printed circuit board.

Elektor Electronics

9/2001

Ω

25 mm

(e.g., Pactec type WM46)

PCB, order code 010005-1 *

Disk, project software, order code

010005-11 *

⋅

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