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 12:26:07 GMT
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Original-From:
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Mike Davis <ipscone@halcyon.=ihatespam=com>
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Viewed:
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1578 times
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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
to 0C. It appeared to download but:
I did not get any sound AND the LCD does not change AND I get an
error stating, "Invalid CONFIG reg (0xFF) try again". If I read this
error correctly, it is suggesting that the configuration reg could
not be changed.
I have checked the orientation and soldering of each chip and the
LCD connector. All is fine. I have also written a small ASSM test
program and verified that it downloads and executes.
I am using an equivelant LCD (DCM16249) listed on handyboard web.
I am using a 68HC811E2 but this should not be a problem since the
EEPROM is disabled.
Any clues as to what the problem might be?
Chuck,
You said you sent out some driver code (LCD I assume). Is is an
assem driver? Where is it?
> Date: Mon, 04 May 1998 11:52:52 -0700
> From: Chuck McManis <cmcmanis@freegate.com>
> Reply-to: cmcmanis@freegate.com
> Organization: FreeGate Corporation
> To: Mike Davis <ipscone@halcyon.com>
> Cc: handyboard@media.mit.edu
> Subject: Re: LCD Addressing - & - Expanded Mode
> > 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 is in Reply To:
 | | Re: LCD Addressing - & - Expanded Mode
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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 (...) That is correct, the LCD is NOT memory (...) (27 years ago, 4-May-98, to lugnet.robotics.handyboard)
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