Atmel AT89S8252 In-Circuit Programmer

• Download the program (runs under Win95 & 98), and unzip into a permanent directory.   Place a shortcut on the desktop to atmelpgm.exe.
• See the circuit diagram for detailed programmer hardware information.
  

Hardware Info

• The programmer has a 40-pin ZIF socket for programming parts out of circuit.  To operate in this mode, use a parallel cable to connect LPT1 on the PC to the DB25 on the programmer; the LED on the programmer should glow dimly.  Attach the external power supply to the programmer; the green LED now should be bright.  Pin 1 of the Atmel AT89S8252 should be positioned at the top of the ZIF socket (nearer to the LED).
• To program a part in-circuit, the design must have included a 6x2 programming header with the appropriate configuration.  See the following two circuits for examples of how to wire this header:  (circuit #1, circuit#2).  When ready to program:
  - attach the programmer to LPT1
  - turn circuit power off
  - attach the special DB9-to-6x2-AMP-header cable between the programmer and the programming header
  - turn on circuit power

Software Info

• Click on the arrow button to load an Intel-hex or binary file.  The A51.exe 8051-assembler generates an Intel-hex output (.obj).  The in-circuit software will generate binary (.bin) files both upon loading an Intel-hex file and when saving the contents of an AT89S8252 flash.  The Reload button reloads the displayed file.  Click on Contents to view the data contained in the file.  The number of bytes in the file will be displayed above the filename.
• Click on Program to load and verify the code contained in the specified file.  Make sure the part is loaded in the ZIF socket or the programming header is attached, and make sure power is applied (external supply if ZIF socket used, and circuit power if programming header is used).
• Click on Erase to empty the contents of the microcontroller.  Click on Read to read out the microcontroller flash.  Once flash contents have been loaded into the PC memory, a "LOADED" flag will appear.  At this point, click on Contents to view the flash data or Save to store the flash data as a binary file.  The number of bytes in the flash will appear above the Read button.
• The Compare button checks if the data in the displayed file matches the data read from the flash.  Data in the flash located after the last address in the file has no impact on a comparison.

NOTE:  when reading the flash, the programming software stops when it sees a string of 50 bytes in a row with the same value.  In the event that a program contains 50 consecutive equal values, a read of the flash WILL TERMINATE PREMATURELY.   This would happen, for example, in programs with large address separations between code chunks.  Programming the flash is not affected by the 50-byte rule; only a read operation may be impacted.