| The Atmel
89C2051 is a 20 pin version of the popular 8051 microcontroller. It's
got only 2k of built-in program memory, but it's Flash ROM, so you can
easily reprogram the chip without the UV erasure step. This really cool
Atmel version has all of the normal 128 bytes of ram (unlike some other
low-cost 20 pin 8051 family members) and they even left the built-in
UART built-in. It's got some other features, but best of all, it costs
only about $5(US) from
Marshall in
single piece quantities. Please keep in mind that neither I nor Oregon
State University represent Atmel or Marshall.
I have designed and
built a simple programmer for this cool part which can reprogram it
in-circuit. You place the 89C2051 in this board, and connect the
board to your project's 20 pin socket with a ribbon cable. You can
download code to the programmer, reprogram the Atmel chip, and then
place the chip back into the circuit. Since it's Flash ROM, no UV erase
step is required. You can reprogram and test your code without moving
the chip between sockets. As well, the programmer supports an
"echo-thru" mode, where the 89C2051's UART output is echoed to the
terminal controlling the 89C2051 in-circuit programmer, but only while
the 89C2051 is running in-circuit.
To get started now, the
design is quite similar to the development board example above, with the
addition of the following chips: 74HC00, CD4007, and four CD4066. The
three unused AND gates in that example are used here. Two NPN and one
PNP small-signal transistors are needed, as well as a 12 volt power
supply for the programming voltage and 4000 series logic. Only one of
the 82C55's is used, but one 82C55 is required.
BETA Version 0.004
is now available, also in
ZIP format. As
well,
BETA Version 0.003
is still available, but 0.004 is much easier to use.
Someday more reasonable
documentation and a schematic of the required hardware will appear. For
now, this
beta release schematic
is available for those who want to try to add the hardware support to an
existing development board.
Other Resources
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