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Information in this knowledgebase article applies to:

  • MCBx51 Boards


The AT89C51RD2 (or T89C51RD2) devices will not connect to the download program using the Atmel FLIP/BatchISP programs.


The device has been programmed previously. Programming these devices automatically disables the ISP functionality.


Use the following steps to download your device with Atmel's FLIP utility:

  1. Set DIP switches 2, 3 and 10 to OFF.
  2. Install a jumper per Application Note 156 on pins 2-3.
  3. Temporarily add a 2.2K ohm resistor between the PSEN pin and ground (GND).
  4. Connect the DB9 serial cable from your PC to the INT connector on the MCBx51 board.
  5. Apply power to the board.
  6. Disconnect the 2.2K ohm resistor between the PSEN pin and ground (GND).
  7. Start the FLIP program.
  8. Select your device from the Device menu.
  9. From the Settings menu, select Communications, then RS232.
  10. Set the COM port, and then baud rate to 9600.
  11. Click Connect at this point, and FLIP should connect and display the device type and other information.
  12. Download your application to the device.

If the above sequence does not work, the bootloader code in flash was overwritten. To restore your device so you can program it, using a parallel device programmer:

  1. Erase the device. This sets the Boot Status Byte (BSB) which allows ISP operation.
  2. Set the Boot Vector Byte (BVB) to 0xFC00.
  3. Load the bootloader code using the attached hex file.
  4. Perform the above steps for downloading your device with Atmel's FLIP utility.




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Last Reviewed: Thursday, October 30, 2008

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