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LCD Hookup — Parallax Forums

LCD Hookup

EMPTY_CEMPTY_C Posts: 29
edited 2013-01-13 20:49 in BASIC Stamp
Hello:

I am planning to receive a few LCDs... More precisely: http://www.purdyelectronics.com/pdf/AND721GST.pdf and http://www.farnell.com/datasheets/1485434.pdf.

How do I interface this with the BS2 and only use 3 pins (vdd, vss and RX) like the ones on the Parallax site.

Thanks for your help!!

MT

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2013-01-10 18:30
    By "3 pins" you mean +V, Gnd, and Data. That's asynchronous serial.
    Your devices use "4-bit" operation (see PDF).
    There are serial backpacks available for LCD - Stamp interface, make sure you get the asynchronous serial (not SPI/I2C)..
    Or use the parallel mode (4-bit).
  • EMPTY_CEMPTY_C Posts: 29
    edited 2013-01-10 18:53
    How do the Parallax LCDs work?... do they have a similar LCD I have selected and then interfaced it with a serial backpack?
  • Mike GreenMike Green Posts: 23,101
    edited 2013-01-10 20:32
    Parallax does have a parallel 2 x 16 LCD very much like the ones you've provided links for. All the other Parallax LCDs are serial. The ones you have all require at least 7 I/O pins (in 4-bit mode) and there is all sorts of sample code for the BASIC Stamp and the 2 x 16 parallel LCD that should be easily modified for other display sizes. The serial LCDs use a different controller chip than the parallel LCDs.

    You can't interface the parallel LCDs using only Vdd, Vss, and a single data pin. The best you could do is to use something like a 74HC595 serial to parallel shift register to provide 8 I/O pins, but use 2 I/O pins to operate (Clk and Data) plus Vdd and Vss.
  • EMPTY_CEMPTY_C Posts: 29
    edited 2013-01-13 18:40
    Mr. Green and Mr. Allen:

    Thank you all for your help!... I did come across this LCD screen also: http://www.newhavendisplay.com/specs/NHD-0220D3Z-NSW-BBW-V3.pdf. Apparently it can use i2c, SPI or TTL... would this be compatable? If so which mode would be best for the BS2? I believe that the TTL mode would use less pins.

    Thanks for your help.

    MT
  • Mike GreenMike Green Posts: 23,101
    edited 2013-01-13 20:49
    It looks like the NewHaven display would work with a BS2. SPI or TTL would be the best modes to use and TTL (serial) would be most like the Parallax LCDs ... you'd use SEROUT to communicate with it. The BS2 does not have built in I2C I/O although you can use subroutines for that. A BS2p does have built-in I2C I/O and you could easily use that with a BS2p/pe/px if you wanted. SPI would use SHIFTOUT. That would work fine with any Stamp, but would be different from the TTL serial.

    Be careful with the time it takes to do some of the control operations. The Parallax LCDs are faster. With the NewHaven LCD, you'd need some PAUSEs after the control operations. The documentation gives the times involved.
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