about isp and psen

[shine]

l can enter isp mode and program the chip successfully when I add the RC at the one PSEN.
but there are more than one chip in my system.if more than one PSEN use the same RC .Flash magic do not work.Who can tell me why ?please

[erikm]

because the other chips which will run activate /PSEN in the normal fashion.

Why not install NoTouch and get rid of the mess.

Erik

[shine]

thank your reply very much .
Maybe to install NoTouch is the best way  .
l just wonder the cause.
PSEN is the output port.
in other words it can not get any logic signal  input
is that right?

[erikm]

l just wonder the cause.

why do you wonder, I already answered

because the other chips which will run activate /PSEN in the normal fashion.

[erikm]

if more than one PSEN use the same RC

bad idea
 
because the other chips which will run activate /PSEN in the normal fashion.

probably you have !psen disabled (AUXR1)on all chips but one.

Erik