Programmable Logic Devices

Discussion in 'Embedded Systems and Microcontrollers' started by adrian.dmc, Dec 31, 2007.

  1. adrian.dmc

    Thread Starter Active Member

    Feb 22, 2007
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    Is there a easy way to program a PAL device like the PAL16L8 at home? I read the datasheet by there's no useful information about that, I also search the net (a bit) and I don't found a thing. Can anyone help me?

    Thx...
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    The programming algorithms are published by the manufacturers as a separate document. Most commercial programmers work with a file format called a JEDEC file after the group that invented it.

    In many cases the programming requires complex waveform drivers for one or more of the pins. I think your chances of coming up with a simple programmer are slim. If you could find one, a Data I/O 29B with some interchangeable heads, on eBay would be a good find.
     
  3. adrian.dmc

    Thread Starter Active Member

    Feb 22, 2007
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    And there's no other way of making one chip make what 3 or 4 chips make, but more simple?
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    Not in an MSI package of up to 40 pins or so. Of course there are huge gate arrays from Xilinx, Altera and others that seem to be where the semiconductor makers have focused their attention.

    Come to think of it PALS started to disappear from the scene about the same time that surface mount assembly took off. On a small package you just can't afford the extra pins for a programming interface the way you can on a 200-400 pin monster gate array. It's a shame really.
     
  5. mrmeval

    Distinguished Member

    Jun 30, 2006
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  6. adrian.dmc

    Thread Starter Active Member

    Feb 22, 2007
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    The solution presented was good if I didn't want to use FFs. But for now it is the simpler method. Probably will have to rethink the design to shrink the sequential part and then the combinational part will be done by the ROM.

    While searching the net I find out that there are other types of devices that perform the same think: like GALs, CPLDs, FPGAs; are they simpler to program?
     
  7. Papabravo

    Expert

    Feb 24, 2006
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    They are basically all the same thing. Different companies had to come up with new an unique marketing names for their devices. Some of the more comples devices get their internal programming from an external serial EEPROM device, just to add an additional level of complexity.

    A device in a thru-hole DIP package can be placed in a prograamer, then place in a socket on a board. With surface mount parts you have to put them on the board blank and then program them through some means. Clearly an OTP (one time programmable) part would be inconvenient for this application.

    Like I said I don't think there is a real good solution for this connundrum.
     
  8. adrian.dmc

    Thread Starter Active Member

    Feb 22, 2007
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    Finally I found what I need to do what I wanted in a very simple way, unfortunately a parallel port or a USB to parallel cable is need, I need the second one and because of that I have a question: a parallel port outputs uses special voltages that cannot be supplied by a USB to parallel cable?
    Where can I get a free program to generate JEDEC files?

    For those who want to do the same (program simple PLDs in a simple way) see: http://www.geocities.com/mwinterhoff/galblast.htm
     
  9. Papabravo

    Expert

    Feb 24, 2006
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    I think you are confusing a parallel port and a serial port. The parallel port uses +5V and Ground.

    The serial port users RS-232 levels which are typically +12VDC and -12VDC. Of course the RS-232 specification allows the positive voltage to be anywhere from +3VDC to +25VDC and the negative level to be between -3VDC and -25VDC.

    -3VDC to +3VDC is no mans land. You can move through there but you can't stay there.
     
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