What's the purpose of this IC in this programmer?

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#1
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Hello guys..

first ,would you please take a look about this two different programmers shown with attachments and then continue reading .

I've worked with programmer in the file programmer3 for a period of time but I didn't pay attention to the IC 74HC245(Octal bus tranceiver; 3-state) until I found the programmer in the file programmer1...

What's the purpose of the IC 74HC245??? :oops: :oops:

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I'd start reading the parallel programmer tutorial:

https://www.avrfreaks.net/index.p...

It answers most of this kind of question and highlights the pitfalls of using these half baked kind of programmers and why certain operation/protection is necessary.

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I used that simple SP12 programmer for years, it worked very well. I didn't bother with the buffered version and left off the RC circuit.

Leon

Leon Heller G1HSM

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Quote:

I used that simple SP12 programmer for years, it worked very well. I didn't bother with the buffered version and left off the RC circuit.

you mean that 74HC245 is just a buffer not more????

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searching for that part from google tells you what? that it's a 32-bit processor?

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Hello....

I've read a part of the parallel programmer tutorial ,and What I understood is that the 74HC244 (74HC245 used here) is just a buffer to protect the parallel port from the outgoing signal from the uC to the printport of the motherboard when the the printport is OFF and the uC is ON >>Is that right??

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It's mainly performing a buffering function to ensure clean signals. I've never had any problems without one.

Leon

Leon Heller G1HSM

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Quote:

It's mainly performing a buffering function to ensure clean signals. I've never had any problems without one.

Plons wrote that tutorial as a problem/answer issue..
So the programmer may work without this additional tip(Buffer) but it may harms the printer port ..

Anyway I like this way of writing because It teaches you and make you pay attention for some problems may occur with newbies (like me) , so thank you very very much Plons/Nard for this wonderful tutorial ...

and thank you clawson and Leon for helping me..

Isam