8051 PROBLEM WITH ISP PROGRAMMER

[silvio]

mcs 51 isp programmer circuit

i meen everywhere the bufer is HCT i have hc is that problem

HCT has TTL input compatible levels and it's suitable for PC parallel port suplied at +5v.
HC has CMOS level, works for the above parallel port but you can have problems using laptop parallel ports.

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Hardware
It is necessary to use the HCT type IC in order to make sure the programmer should also work with the 3V type parallel port

when i uplod ff-s buffer, no problem , but when i read, in chip was some values .... diferent from ff

It reading sigtnature perfect, reading flash perfect

Every new AT89S52 comes from the factory with the flash cell memory in FF.
If you have the programming buffer filled with FF and perform a read of a brand new chip it's obvious you can read it succesfully, without errors.
That happens even if your software reads a pin 10 of LPT port - nACK (status register) as always 1, regardless of the value of AT89S52 flash memory.
If your buffer is filled now with your hex code and you read always FF from AT89S52 due to "unknown" reasons, well it's natural to receive errors.
And that doesn't means it reads perfect the flash.
I ask you to come back with an answer regarding three bytes signature, exactly shown by the software program not read from datasheet.

 

[syrax]

philips 8051 signature bytes

Now the signature is OK
I wrote the chip before /with AEC/
I can read Flash /verify after that /
LPT/on my old notebook/ is wtih 5V pins
Is the possible problem in the chip, i will try with empty chips
The problem is only with erasing and programing
and the end of chip i have something like thet:
0fff0fff0fff0fff0fff
0fff0fff0fff0fff0fff.....
may be the chip is damaged

 

[mUNISH]

isp programmer for 8051

I had made Asim Khan's ISP programmer some 4 months ago. I built the schematic exactly as stated, but it didn't work as expected. Sometimes it just reads the uC i.e. it does show the device signature correct, but doesn't program it. And sometimes not even that. It just shows a dialog box that ". I had nobody to go to for fixing it for quite a long time

I have an IBM ThinkPad. So once I suspected the LPT port to be the culprit. Is there a difference between the (voltage levels) of LPT of a laptop and that of a regular desktop, and do they require buffering in case of Laptops? I was forced to think so because somewhere I had read that the cause of using 74HCT541 (and not 74LS541) is that they should work with 3V type parallel ports !

I tried to use 74LS541 with my laptop's parallel port, but now it doesn't even show the signature...

SOMEBUDDY HELP ME !!!

 

[hulahula]

isp flash programmer 3.7

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