Author :
Wichit
Sirichote
Introduction
The
first
version
of the
Easy-Downloader
was
designed
in 1997
to be
used as
a tool
for my
students
on
building
her/his
own
microcontrollers
circuit
in the
class "
Designing
Microprocessors
System".
The
circuit
features
low-cost
and easy
use. The
latest
version
V1.1 was
designed
to be
used
with
2051 and
the
newest
4051
chips.
There is
no
separate
functions
like
other
programmer
e.g.,
blank
check,
erase,
write.
Simply
type
say,
c:\..>ez
hello ,
the hex
file "hello.hex"
will
then be
programmed
to the
chip
automatically.
If the
chip is
not
blank or
the code
is
locked,
it will
erase
first,
then
write
and
verify...
that
all.
Hardware
Figure 1
shows a
circuit
diagram
of the
Easy-Downloader.
As
shown,
the
circuit
uses a
89C2051
with
writer.hex
firmware,
74LS373
8-bit
latch,
DS275-like,
7805,
LM317
and two
transistors,
2N2222A
and
2N2907A.
The
programming
voltage
control
circuit
is the
same as
recommended
by ATMEL
application
note. It
can be
raised
from 0V,
5V and
12V by
appropriated
signal
from P3.
The
8-bit
latch,
74LS373
provides
some
signal
for
selecting
the
programming
modes. A
byte to
be
programmed
or read
back is
sent/received
through
P1.
Incrementing
address
is done
by
pulsing
a
positive
pulse to
XTAL
pin. The
circuit
may be
built
using
simple
point-to-point
soldering
with a
general
purpose
PCB(
fish's
egg like
PCB) or
making
PCB
shown
above,
the file
is
Easy-v1.pcb
Protel
PCB
version
2.76.
The
finished
board
should
be
tested
without
any
chips;
1) +5V
supply,
2)
programming
voltage
0V, 5V
and 12V
by
connecting
the pin
that
control
(P3.5
and D)
2N2222A
and
2N2907
to +5V
and/or
GND. The
adapter
output
should
be
approx.
15Vdc
100mA.
Click
here for
more
detail &
source
code |
