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I follow this link: http://m955.com/wp/archives/142

I will buy:

1.printer port

2.a line has both printer port and rs232

3.a line has both rs232 and usb

Is these ok for sending computer signal from usb to rs232 to printer port to make the whole circuit work? Should I need any usb chip? If yes,how to make it?

Thank you~

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It looks like I misunderstood the question. If you want to use a parallel port programmer to program the chip, then what you list is the right list.

One thing worth noting is that depending on parallel port implementation, you might have trouble programming over USB to parallel port cables, so I'd recommend that you get a card with a parallel port or even better with a parallel port and a serial port.

Do note that you can make also make a programmer using just a serial port too, so there would be no need to get a printer port in that case.

The USB port on the picture is only used for power, so no chip would be needed. You could, if you wanted, use a chip such as one of the FTDI or Prolific chips to get both power and to allow the device to work talk to the computer over RS-232. Another benefit of using a chip is that on USB 2.0 (and earlier) ports you can use up to 500 mA of current while without the chip, you're limited to 100 mA.

As far as the circuit for a USB to serial chip is concerned, I can't help you right now. You'll need to find a chip you want to use and read its datasheet. If you have any problems after doing that, you're free to ask a question explaining what isn't clear and we'll answer.

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    \$\begingroup\$ @Paul - the schematic OP linked to clearly shows a parallel printer port. \$\endgroup\$ – stevenvh Oct 8 '11 at 10:03
  • \$\begingroup\$ @Paul R The text is actually about programming the chip and does not mention anything about communication with a printer, as far as Google Translate say. It actually looks like a parallel port programmer! \$\endgroup\$ – AndrejaKo Oct 8 '11 at 12:48
  • \$\begingroup\$ @AndrejaKo I just see these answers right now.I am confused that what kind of concept you misunderstand? \$\endgroup\$ – sam Oct 8 '11 at 14:44
  • \$\begingroup\$ @sam I changed my answer, so it looks like you missed the old one. You can find that version here. Anyway, did I get your intention correctly? Do you wan to program the chip using the equipment you listed? \$\endgroup\$ – AndrejaKo Oct 8 '11 at 16:52
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    \$\begingroup\$ @sam Yes, I mean get a PCI or PCI-E card with a parallel port. The programmers such as the one you showed are called "bit banging" programmers and they program a chip using a port which isn't actually intended to program a chip by producing required signals in software. Due to some limitations of USB, it cannot be used to generate such signals quickly enough, so programmers which use USB to RS-232 or USB to parallel port cables can be very slow. \$\endgroup\$ – AndrejaKo Oct 10 '11 at 5:51

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