PSEN stays at 5V!

[ascopie]

Hello,

I'm trying for the first time to program the P89C664 with flash magic (i manually control the PSEN and Reset line). I tried several times but it doesn't work, moreover, when connecting the PSEN line with a resistor of 2 k to ground, the PSEN pin stays at 4,7 V ? Is anybody familiar with that?

Also i've send the 'U' command using 'hyperterminal' but the

[ascopie]

OK, it works ! all problems are solved .....

[Andy Ayre]

Can you post what you found and what the solution was? It might benefit future readers of this forum. Thanks!

[ascopie]

hi,

i don't know what the problem exactly was, but i've made a new testboard and now it works, even now PSEN stays at 4,7 V but it works fine,
(I can program the P89C664 and in Hyperterminal it reply's to an "U"  in program mode off course)

The only thing that could have caused the problem is maybe the RXD and TXD wires that were too long.  
Just read the AN461, built the circuit like it says, and it will work just fine.
Note that P2.6 en P2.7 must be "high" of "floating"...

greetz