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OTP my stamp? — Parallax Forums

OTP my stamp?

stlericstleric Posts: 13
edited 2012-12-13 13:12 in BASIC Stamp
For no particular reason, I got to wondering: If I wrote a Stamp program (BS2, let's say) that had no way to quit, just runs in an endless loop and used pins 1 and 2 for SERIN/SEROUT would I have just turned my Stamp into a OTP device?

If so, to avoid this OTP trap I should do at least one of the following:
1. Have a way to quit the program
2. Use don't use pin 1 and 2 for SERIN/SEROUT
3. If I do use pin 1 and 2 for serial comms, then use the DEBUG/DEBUGIN
Is that right?

TIA
eric

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2012-12-13 11:40
    The only OTP trap would be to have no connection to module pins 1-3 (SOUT, SIN, ATN). Pulsing ATN low will reset the Stamp and the built-in Stamp interpreter will attempt to download a program from a PC attached to those pins. Some people have made a "OTP" board by having a 4-pin header on the board connected to pins 1-3 and ground. The header can be attached to the serial interface shown in the Stamp Manual for programming, then the header is left closed into the box.

    As long as you have access to ATN, your Stamp program can be interrupted and a new program downloaded via SOUT and SIN.
  • davejamesdavejames Posts: 4,047
    edited 2012-12-13 12:07
    ...all right, I'll bite:

    OTP? Wazzat?
  • Mike GreenMike Green Posts: 23,101
    edited 2012-12-13 12:20
    One Time Programming

    Originally PROMs were electrically programmable, but had to be erased with UV light applied through quartz windows on the top of ceramic/metal packages. This sort of package is expensive. Semiconductor companies began selling the same chips packaged in plastic as OTP parts. You could program them the usual way, but couldn't erase them through the opaque packages. Theoretically, you could erase them with x-rays, but this was not commonly used. They could be programmed once. This was used for stable production code where the cost of rare replacement was small compared to the incremental cost of the erasable package.
  • davejamesdavejames Posts: 4,047
    edited 2012-12-13 12:27
    Mike Green wrote: »
    One Time Programming

    ...thank you.

    Yup - Intel 1702s...gotta love that quartz window:
    Chip-Intel1702EPROM.jpg

    Those skinny legs made them a bear to load into burn-in trays!
    Chip-Intel1702EPROM.jpg
    640 x 480 - 22K
  • stlericstleric Posts: 13
    edited 2012-12-13 13:12
    Mike Green wrote: »
    The only OTP trap would be to have no connection to module pins 1-3 (SOUT, SIN, ATN). Pulsing ATN low will reset the Stamp and the built-in Stamp interpreter will attempt to download a program from a PC attached to those pins. Some people have made a "OTP" board by having a 4-pin header on the board connected to pins 1-3 and ground. The header can be attached to the serial interface shown in the Stamp Manual for programming, then the header is left closed into the box.

    As long as you have access to ATN, your Stamp program can be interrupted and a new program downloaded via SOUT and SIN.

    Nice.

    Thanks
    eric
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