ISP problem with RD2

[suyash kulkarni]

To all

I had been using P89C51RD2HBN (1st generation RD2) device. Recently I had upgrade my product to P89C51RD2BN (2nd generation) Now I am facing following problem.

In my product for firmware update I use following procedure. After receiving command through RS232. The CPU enables boot-rom bit and then jumps to FC00 location. Then by using WinISP (2.28) we program the device, After hardware reset it start executing my application code. For Older RD2 this was working fine, but for new device after updating code-using WinISP and after hardware reset it is not executing my application code.

I had also tryed Falsh magic but it give same problem

If any body know the solution then please help

suyash kulkarni

[Andy Ayre]

I don't know of anything specific that could be causing your problem, but these devices do feature a watchdog. My recommendation is that you use the watchdog whenever possible to reset the device into the bootrom rather than performing a jump to FC00H. This guarantees that all the SFRs and internal registers and hardware of the device is properly reset.

Set Status Byte
Ensure Boot Vector is set to FCH (which it should be if you have never changed it)
Turn on watchdog
Wait forever