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RS232 advice — Parallax Forums

RS232 advice

TCTC Posts: 1,019
edited 2014-01-23 05:25 in General Discussion
Hello all, I received a Noritake Itron sample CU24063 -Y100 display yesterday. I love the thing. But it is set up for RS232 serial. The data sheet says, Low input = -15 to 0.5, and High input = 3 to +15.

I dont think I would have any problems hooking it to the outputs of a stamp, or a prop. But I figured it could not hurt to have a circuit to convert to RS232 just for it. But the thing I am having trouble deciding on is I only need TXD, and CTS.

What do you think would be my best option? or ideas?

Thanks
TC

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2014-01-23 04:50
    There is no harm in trying the Stamp with the display without a serial converter chip. It sounds like the display is built for "real" rs-232 signal levels and will probably work either through the Stamp's programming port (16) or any other pin with SEROUT.

    Even though the rs-232 standard has an undefined area near zero volts, most modern rs-232 compliant devices will successfully interpret 0v as a Low (logic 1) and +5 as a High (logic 0).

    If want to go the converter-chip route, I'd suggest a Max 233 which does not need external capacitors.

    Let us know how you make out.

    Cheers,
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2014-01-23 05:13
    TC wrote: »
    Hello all, I received a Noritake Itron sample CU24063 -Y100 display yesterday. I love the thing. But it is set up for RS232 serial. The data sheet says, Low input = -15 to 0.5, and High input = 3 to +15.

    I dont think I would have any problems hooking it to the outputs of a stamp, or a prop. But I figured it could not hurt to have a circuit to convert to RS232 just for it. But the thing I am having trouble deciding on is I only need TXD, and CTS.

    What do you think would be my best option? or ideas?

    Thanks
    TC

    Datasheet Electrical Characteristics indicates logic levels are acceptable, even 3.3V levels, which is what I expect and quite probably they aren't using any kind of RS232 chip at all, maybe just a protected logic input. The SBUSY signal is IMO optional but it is only 0..5V level so if you feed it into the Prop then just use a series 10K resistor or so.
  • TCTC Posts: 1,019
    edited 2014-01-23 05:13
    stamptrol wrote: »
    There is no harm in trying the Stamp with the display without a serial converter chip. It sounds like the display is built for "real" rs-232 signal levels and will probably work either through the Stamp's programming port (16) or any other pin with SEROUT.

    Even though the rs-232 standard has an undefined area near zero volts, most modern rs-232 compliant devices will successfully interpret 0v as a Low (logic 1) and +5 as a High (logic 0).

    If want to go the converter-chip route, I'd suggest a Max 233 which does not need external capacitors.

    Let us know how you make out.

    Cheers,

    Do you think it would work with the Propeller?

    I took a closer look at the data sheet, and it says the display is CMOS compatible. Just the data would have to be inverted. I don't know much about CMOS, TTL, etc...
  • TCTC Posts: 1,019
    edited 2014-01-23 05:25
    Peter Jakacki wrote: »
    Datasheet Electrical Characteristics indicates logic levels are acceptable, even 3.3V levels, which is what I expect and quite probably they aren't using any kind of RS232 chip at all, maybe just a protected logic input. The SBUSY signal is IMO optional but it is only 0..5V level so if you feed it into the Prop then just use a series 10K resistor or so.

    Wonderful. That was my assumption, but I figure it could not hurt to find out. Thanks
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