Subject:
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Re: LCD Addressing - & - Expanded Mode
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 4 May 1998 18:52:52 GMT
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Original-From:
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Chuck McManis <cmcmanis@freegate.=SayNoToSpam=com>
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Reply-To:
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cmcmanis@freegate.&StopSpammers&com
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Viewed:
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1556 times
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From the driver code I recently sent out:
* LCD Connections on the Handyboard
* PORTB bit 0 - R/W
* PORTB bit 1 - RS (Register Select, 0 = instruction)
* PORTC 8 bits of Data
* PORTA bit 4 - E clock
Mike Davis wrote:
> Does this mean that the LCD is NOT memory mapped?
That is correct, the LCD is NOT memory mapped, it is connected
directly to the pins on the 68HC11 that become ports A, B, and C
in "single chip" mode.
> Do I first have to write to Port B then write to Port A, to clock
> it.
That is correct.
Something like:
Write B
Write C (this is your data)
Write the clock high
NOP
Write the clock low
(The NOP is to insure the timing requirements of the LCD are met,
you can leave it out but it can screw up when the LCD is cold)
> This must mean that I have to go into and out of expanded mode to
> use both the LCD and the SRAM? That's kinda wierd.
Not exactly, it means the SRAM is unavailable to you when you are
in single chip mode, however there is at least 256 bytes of RAM
addressed at address 0 that is available (its inside the
processor). It's not "kinda" weird, it is very, very weird.
> Anything else you can point me to as far as addressing the LCD and
> accessing SRAM via assembly code?
Other than the source I sent out? Not really. Note that you can't
address SRAM easily in single chip mode. I suspect it is possible
but it is much easier to copy stuff from SRAM into the first 256
bytes before you switch into single chip mode.
--Chuck
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Message has 3 Replies:
 | | Re: LCD Addressing - & - Expanded Mode
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| Wierd: Anyway I have some kind of problem with the handyboard. All steps up to the testing of the LCD went fine. When I plugged in the LCD and turned it on, it lights up (one line) bright not dim. I tried to download the pcode_hb.s19 with config set (...) (27 years ago, 4-May-98, to lugnet.robotics.handyboard)
| | | Re: LCD Addressing - & - Expanded Mode
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| I found the driver you sent earlier. Thanks. BTW, I found out that my LCD is good but I still have a problem. It appears that I cannot change my CONFIG reg. Maybe because it is an 811E2; don't know. Should be able to however. Since the program was (...) (27 years ago, 4-May-98, to lugnet.robotics.handyboard)
| | | Re: LCD Addressing
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| Mike, Chuck McManis may have answered your request, but in case you still want sample code I am attaching an example code that prints to the HandyBoard display. (The code forms part of the Handy Board buffalo I had developed). I had trouble getting (...) (27 years ago, 5-May-98, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: LCD Addressing - & - Expanded Mode
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| So, this still doesn't help me figure out how to address the LCD. It has A8 and A9 connected along with a CLK from Port A. Does this mean that the LCD is NOT memory mapped? Do I first have to write to Port B then write to Port A, to clock it. This (...) (27 years ago, 4-May-98, to lugnet.robotics.handyboard)
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