Hi ,
i have been using Mr. Asim Khan's programmer ( http://chaokhun.kmitl.ac.th/~kswichit...gm30a.html )for programming Atmel AT89Sxxxx devices in DIP package.
now i've designed a Simple Board Based on the AT89S52 TQFP package and i couldn't even read back the Signature !.
I have tried 24 ,11.0592 ,4 Mhz crystals with no luck , the software reports 'byte1 = 00 , byte2 = 00 , byte3 = 00' for the signature read :( .
if i persist i could get 1E for the first byte or C0 or some other values i have got the real signature very very rarely (1/200) which is 1E 52 06.
the cable from the pc to the programmer board is about 1 meter long flat cable.
programmer board contains a HCT541 buffer and another 1 meter flat cable connects the programmer to the ISP socket on my PCB.

seems that the chip don't talks back to the PC, i checked with the Scope but i see some transitions on the MISO line (Voltage levels seem correct on the scope), unfortunately my Scope cannot store the signal so i don't know what is being conversated between the two devices.

did i missed something here? are the TQPF packages capable of ISP ?

Here is the pcb layout :

and refer to this link for the schematic (it was a bit big so i did posted the link) :
schematic
Best Regards :
Farshid J.H.