How to reprogram ISP mode entry

[SARAVANAN]

Hi,

        I have got an 89V51RD2BN dev board and unfortunately I programmed the ISP mode entry to run user code, thinking that I can reprogram it to run boot loader later. But now I couldnt enter ISP mode and no autobaud happens. So is there any way I can return back other than a parallel programmer??? Thanks

[Andy Ayre]

After reset there is about a 400ms window in which to send a 'U' to the RxD pin. If the device detect the 'U' then it enters the bootloader.

Andy

[SARAVANAN]

Thanks for the reply

will try it out.

Thanks again