Re: Cleanest Ada way to do this?

[hungupharps@gmail.com]

On Sunday, June 22, 2014 5:17:49 PM UTC-7, Simon Clubley wrote:
> 
> There will probably only be one 32 bit port in use for the LCD and only
> 
> a small subset of the bits will probably be in use (at least for driving
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> the LCD if it's the type of LCD I think it is).
> 
> 
> 
> It looks like Mike is implementing the traditional character LCD driver.
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> Intermixed with the display data will probably be command data including
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> things like cursor addressing and there will probably be additional I/O
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> lines for things like Read/Write select and data/command mode.
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> 
> 
> However, to reduce the amount of I/O pins you need to wire up, you can
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> command the LCD module to switch from 8-bit mode to 4-bit mode so you
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> end up sending each command or data character as two nibbles and that
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> looks like what Mike has done here.
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> 
> 
> My first pass at a design for this would be a 32-bit record type with
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> the bitfields laid out to correspond with the actual wiring of the I/O
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> port, so he has separate bitfields for both the R/W and data/command
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> lines as well as a 4-bit wide field for the above data lines.

Yes, it's that type of LCD.  4 data lines, an E signal and a RS (register select) signal.  Hard-wire the R/W line to GND.

Ignoring the control signals (they will just be writes to separate atomic set or reset registers, to avoid a RMW cycle), what might this code look like?  I've got a bitfield representing the LCD data lines and I'm trying then to write bits from a Character into it.