Hi everybody,

i have a problem to program AT89S8252 through ISP serial interface.

I know there is a very similar thread (http://www.8052.com/forum/read.phtml?id=77724) with such a problem, but there was used an LPT PC programmer interface. I went through that thread, tried the solutions written ther but neither helped.

So to get to the problem. I built a ISP serial programmer. I was inspired with the article:
http://www.siliconchip.com.au/cms/A_304...ticle.html
My programmer schematic is same as in the article. You can find it on http://www.8052.com/users/battika/

I tested this programmer on MCU AT90S232 than ATMEGA32L. I used AvrProg software from AVR studio. Sometimes the programming suceed sometimes failed. My main aim was to program AT89S8252 but it failed all the time.

When I removed the 100 ohm resistor R4 from SCK the programming get stable with MCU's AT90S232, ATMEGA32L, but still it didn't work with AT89S8252.

I tried to remove all 100 ohm resistor, but nothing helped. I use 16Mhz chrystal and 33pf condensators for the AT89S8252. All the MISO, SCK, RST, MOSI lines are directly connected to the MCU. I checked the enable serial programmign flag is enabled, but nothing helped.

I tried AVRDude software instead of AVRProg (also supports AT89S8252), but it could not recognize the MCU. Unfotunately I don't have oscylloscop to check the MOSI and MISO lines.
If you have any idea's how to solve this problem I would be very happy.

Thanx in advance

Attila