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9958Re: [cosmacelf] Re: Seven Segment Displays

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  • Kent Andersen
    Apr 5, 2012
      I see, I will have to try that out. Wonderful info!
      I have a large quantity of these
      www.datasheetarchive.com/LCD%201602%20display-datasheet.html# Ie the
      1602 16x2 LCD displays that I use a lot with the ATmega embedded cpu's
      Most of the difficult stuff is already done there with a library that is
      used to communicate to it. I would love to think I could use them
      instead of the TIL type displays to give some useful memory
      location/data information on them.

      If anyone is interested they are like .99 cents on ebay are nicely
      backlit and as common you can get. I bought 20 of them a while back and
      love them to death for my applications.

      Kent

      On 4/5/2012 2:14 PM, Rick Cortese wrote:
      >
      > Forewarning: Been over 30 years since I last did something original
      > with an 1802. As Lee points out, you really need a data sheet to make
      > sure how your LCD operate. The pinouts on the interfaces come in a
      > couple of flavors, 14 pin, or 2x7 pins are the most common and I
      > think somewhat standard. The the Jameco have 16 pins with the
      > additional pins for the backlight.
      >
      > If I was to try hooking one up:
      >
      > I would tie the data lines 1:1 with the 1802.
      >
      > I would tie the R/W low to keep it in write mode. They do have a ~64
      > bytes of RAM on them for redefined characters but I don't really think
      > it would be necessary to access it in read/write mode. Ditto for the
      > display memory, you can retrieve what is written to it but 2X16 is not
      > enough memory to bother with.
      >
      > The register select pin I would think about tying to the 1802 address
      > line MA0 or just use Q to be safe. I forgot what happens to memory
      > address lines during and OUTPUT instruction. <DOH!> If they stay the
      > same for the output cycle you could just read from memory location
      > XXXXXXX0 and XXXXXXX1 to set the LCD register select pins then follow
      > with the OUTPUT 1<for instance> 1802 instruction. Q line is much
      > easier, just set it for operation and be sure. As Lee said, since they
      > have the 4 bit mode you probably could use one of the data lines for
      > register select line but you may need a delay for the 4 bits for set
      > up time.
      >
      > The LCD enable pin I would tie to one of the N0-N2 outputs of the
      > 1802. I think its operation is inverted from what we have with the
      > 1802. That is it would have to be run through a 4049 or something to
      > get the polarity right. Back in the day I routed mine though a 74LS138
      > so I could have 8 output devices. IIRC a 74ls138 has inverted outputs
      > so it could replace the 4049 and give you up to 8 I/O chips/devices.
      > Of course you would want to use something like a 74C138 or 74HTC138 to
      > keep with the low power theme.
      >
      > In use you would just
      > set Q level for command byte, OUTPUT1 command byte
      > set Q level data byte, OUTPUT1 data.
      >
      > I've probably committed some grievous oversight in how I would do it.
      > IMHO, it would be a cute hack.
      >
      > ________________________________
      > From: Kent Andersen <sci@... <mailto:sci%40altazip.com>>
      > To: cosmacelf@yahoogroups.com <mailto:cosmacelf%40yahoogroups.com>
      > Sent: Wednesday, April 4, 2012 9:20 PM
      > Subject: Re: [cosmacelf] Re: Seven Segment Displays
      >
      >
      >
      > how do you use displays like that? I have a pile of those types of
      > displays that I use with arduino (Atmega) but I have never seen anyone
      > interface one of these puppies to a 1802.
      >
      > On 4/3/2012 5:31 PM, eight_bit_jdrose wrote:
      > >
      > >
      > >
      > > --- In cosmacelf@yahoogroups.com
      > <mailto:cosmacelf%40yahoogroups.com>
      > <mailto:cosmacelf%40yahoogroups.com>,
      > > Lee Hart <leeahart@...> wrote:
      > > >
      > >
      > > > > I have used the 2X16 character displays like
      > > > >
      > >
      > http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2118580_-1
      > > >
      > >
      > > Mr. Hart,
      > >
      > > That is a nice, contrasty display at a decent price.
      > >
      > > Do you know if there is a version of this display that is serial
      > instead?
      > >
      > >
      >
      > [Non-text portions of this message have been removed]
      >
      > [Non-text portions of this message have been removed]
      >
      >



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