*    EEPROM Burners and Erasers are eliminated. Erase time is eliminated.
*    ISP Devices can be soldered to the board before they are programmed, making SMT a viable option for the
            hobbyist, and for low volume production runs.
*    There is no need to have a range of programming sockets for different IC packages.
*    Your code can be updated anytime.
*    There is less chance of electrostatic damage and physical stress on the components as they no longer need to
            be removed from their sockets during code development.
*    Development cycle times are greatly reduced.
*    ISP Parts and tools are cheap.
 

V3.00 now supports the following devices: AT89S51, AT89S52, AT89S53, AT89S8252, and allows LPT2 to be used.

By simply connecting a cable between your printer port (LPT1 or LPT2) and your target system, you can download code to the AT89S device.

Your code needs to be in Intel Hex format. AEC_ISP will open the file you specify and load it into a buffer. (Note: you can specify a default file in the command line; eg: To specify TEST.HEX as the default file, start AEC_ISP by typing 'AEC_ISP TEST.HEX'.)

The connections between the PC and microcontroller are shown below. Note that the specified microcontroller pins are for the 40 pin DIL (Dual In Line) package only.

Use a standard male D25 connector to connect to the PC printer Port. For best results, use twisted pair cable (use 4 pairs), with each signal line paired with a GND line. Connect all GND lines to the same pin in the D25 connector, but only connect 1 GND line to the target hardware. Make sure the cable is no longer that 1m. Select a 5way connector that best matches your hardware.

The Target hardware must provide a 5V supply to the microcontroller, and must provide a 4 -24 MHz clock to the XTAL 1 pin (either from a crystal or some other external drive circuitry). Be aware of (and avoid) differences in ground potential between your hardware and your PC.

An effective way to control the RESET pin of the micro is shown below:
 

Some PC's can source quite a bit of power from their Printer ports. If your PC is connected to your target system but there is no power to the AT89S device, the PC will still source current to the system through P1.5 and P1.7 of the micro. To avoid this problem, use 1k5 resistors between your ISP connector and these pins - but always disconnect the cable before turning off the target hardware. Also, remember that if there is a fault on your system, you may be supplying unwanted and destructive power to the PC!

If P1.5, P1.6 or P1.7 need to have functions other than for In System Programming, make sure you are very careful about how you use them. You can use these pins as outputs without any problem - but remember that the peripheral circuitry will respond to the programming signals. If you use the surrounding circuitry to provide data to these pins (inputs), make sure it does not create conflicts during programming.

As far as using the software goes, it is self explanatory. If you want to know more about the transfer protocols, read the ATMEL data book.

AEC_ISP may be used in any way, for any purpose, at NO COST. It may be distributed by any means, provided that the original files as supplied by the author remain intact and no charge is made other than for reasonable distribution costs.

AEC_ISP may not be distributed with any commercial product without a prior license agreement with AEC Electronics Ltd.

THE INFORMATION AND CODE PROVIDED IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL AEC ELECTRONICS LTD BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF AEC ELECTRONICS LTD HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.