Reset problem with P89C51RC2

Started by sandre, December 03, 2004, 04:45:17 AM

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here is my problem : the program I wrote starts only at power-on reset, when I press the reset button the microcontroller allways seems to boot on ISP and not on my program.

The target is a P89C51RC2 burned with WinISP (Philips), Status byte = 0x00 and Boot vector = 0xFC.

Does someone know the solution to solve my problem ? Thank you.


have you confused reset with !reset, someone else did.


Andy Ayre

The state of PSEN is used like a switch at reset to determine whether the device goes into ISP mode or not. Check the voltage on that pin.

This forum no longer supports WinISP, so you might want to switch to Flash Magic (less bugs).

Note that WinISP does not properly support the 89C51RC2xx. It only supports the 89C51RC2Hxx.

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Thank you very much ! In fact the PSEN pin in pulled-down by a 12ohms resistor. I will remove it.