Hello everyone,
There are always many posts here asking about ISP programmers for the atmel 89S51 or 89S52 mcu's. Most commonly available are the FREE programmers that use the parallel port of your PC.
These programmers are not reliable, or do not work consistently on some parallel ports. If you happened to get stuck with a motherboard on your PC like mine, you would be lucky to get the programmer to read the signature bytes especially with windows XP or higher. These days computers are no longer equipped with a parallel port. I have been using this programmer for a few years now reliably even with a USB to serial adapter cable.
I use the 89S series mcu's quite a bit because they are inexpensive and easy to program (no fuses, or other problems). I wanted an easy to use programmer that would allow me to program the 89S mcu's in circuit without removing it every time.
I did not want to go through all the trouble to write a windows application, so I thought I would just use an existing one and modify the code in the programmer to do ISP operations instead of high voltage parallel programming as in the 89S51/89C52. I chose this one:
**broken link removed**
The ezdl4.exe has nothing to do with me and does not need to be changed to work with this programmer.
The circuit I chose was the same circuit as an avr910 programmer except that an 8051 device is used for the programmer. (the reset circuit will be different and the crystal will be 11.0592MHz) I chose this because I already have an avr910 programmer board therfore I would not have to go through the trouble of making another board.
Have a look at the schematic below. You can use any 8051 mcu for the programmer as long as you adhere to the pinout, and it must hold at least 4K in size. The circuit can take power from your target, or supply power to the target, if the power from the programmer (as with the avr910 programmer) is connected to your target circuit.
Now the only problem is: Somehow you have to get the code into an 8051 MCU. If you do not have a programmer, this will be a problem. Once that is done you will have a very reliable programmer.
Everything is included in the zip file. Please read the readme.txt for instructions.
Any suggestions are welcome. Please post them here.
ctownsend