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Serial programmers?

Discussion in 'Electronic Basics' started by Lessie, Mar 27, 2005.

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  1. Lessie

    Lessie Guest

    I was just wondering how serial programmers work, i.e.
    we need two lines, one for clock, and one for data.
    Which serial line is used to send the clock to the
    device? I assume the data uses RD/TD
  2. Wim Lewis

    Wim Lewis Guest

    Most serial programmers use the serial port as if it were just a
    very strange parallel port. The modem control and flow control
    lines (DTR, DSR, RTS, CTS, RI, CD) can be set and read individually,
    and that's enough bits of I/O there to program something. They might not
    even use RxD / TxD.

    Another advantage of the serial port is that you can usually draw enough
    current from it to power the chip while you're programming it.
  3. The serial programming interfaces I have seen do not use the serial port
    on the computer. They use the parallell port.

    Look at this serial programming interface for atmel microprocessors;

    The hardware consists of a few wires, more than 2 though, from the
    parallell port to the microprocessor.

    To me "a serial programmer" means that it uses serial technology into the
    device, but it doesn't mean that a standard serial interface as in serial
    ports are used.

  4. After seeing Win Lewis answer I can add, yes sometimes the serial port is
    used too, but it often gets more complicated, like in these adapters for
    the same devices:

    The bottom line is, the "serial" in serial programmers is not saying
    anything about what ports you use on the computer, it is about how data
    is programmed into the device. And the communication does not follow
    the regular serial interface protocol.
  5. Lessie

    Lessie Guest

    Sorry, I forgot to mention what I was talking about, I meant pic
    programmers (microchip) which connect from the serial port
    of the pc.
    Here is my problem. If I have visyal basic I can use
    MSComm object to read and send characters to the serial
    line. The problem, as far as I can see, is the clock, as there
    is no extra send/receive line
    Any ideas as to how to do that with win2000 and vb6 ?

  6. A serial programmer for PICs can be found at

    petrus bitbyter
  7. It isn't. Details of the programmer are on

    petrus bitbyter
  8. Lessie

    Lessie Guest

    A serial programmer for PICs can be found at
    thanks, maybe this is what I need, can you be more specific
    with the link, as it seems to be an entry point of a random
  9. Rich Grise

    Rich Grise Guest

    If you're using "the serial port" and sending and receiving characters
    with a comm DLL, then no "clock" is needed - the receiving device
    figures out the 1's and 0's based on the start bit, n data bits, and
    stop bit, and all of the bits are sent at some previously-agreed-on

    So we might be talking apples and oranges here. It sounds like you
    have a whole development kit, which talks to the computer with a
    comm line.

    The others seen to think you're referring to the chip itself,
    which might or might not be using a UART. To bitbang serial
    data to a chip that has "data" and "clock" lines, you have to
    wiggle individual bits.

    Hope This Helps!
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