P89c51 Boot/ISP Code

[Russ]

Support,

I have two designs with the Philip 89c51 Microcontroller which
supports ISP (In-System Programming).  I have been unable to
make the ISP function work properly.  I believe this is due
to the BOOT/ISP code being erased in my 89c51 micro-controllers.

Do you have or know where I can acquire the proper code to
reprogram my micro controllers so that I can utilize the
ISP feature.

Thank You
Russ Sanders
EACSI

[Andy Ayre]

It is not possible to erase the Bootloader in Philips devices except for the LPC932, however it is possible to program or erase the Boot Vector to an incorrect value, which will stop the device from finding the bootloader. If this is the case then the only solution is to use a parallel programmer to program the Boot Vector back to the default value. If you do not have a parallel programmer then there is no way of recovering the device.

However, not being able to get the device back into ISP mode may be due to a number of things. Incorrect voltages on the necessary pins at reset, defective or static damaged device, incorrect baudrate, I even see people have faulty PC COM Ports.

I suggest that you go to the Flash Magic web page and download the application note on ISP problems. It will take you through a number of steps to try and determine what the problem is. If all else fails, it gives you the procedure to Email me a Flash Magic generated debug file, allowing me to see what is going on with the serial comms.