On Tue, 14 Mar 2000, John Mitchell wrote:
> On Mon, 13 Mar 2000, Micah Dowty wrote:
> > On Mon, 13 Mar 2000, Freeman,DI,David,NZD3 R wrote:
> > > HI,
> > >
> > > I very much like the look of this device.
> so do I!
> > > 3. How have you made the keyboard?
> > No, the one in the prototype is a surplus Dauphin keyboard from
> > www.all-electronics.com, the LCD was also purchased surplus from there.
> > The LCD works ok, but the fact that it requires +/- 5v is annoying.
> > Anybody know of better places to get a keyboard and LCD?
> Another suggestion: use a charge pump to generate the +/- 5v. You
> probably have a Maxim MAX232 for your serial connection anyway, right?
> It has *two* buffers - use one for serial, the other for the LCD.
Maxim seems to make a lot of chips that can 'automagically' convert
I am using a maxim chip for my 3.3v supply (I have a picture of the
supply on homesoftware.com), and I will also be using one for the LCD
power supply. The 3.3v supply is impressive, it will run even on a pair of
AA batteries discharded to 0.6v per cell! My serial port driver is not a
MAX232- to the best of my knowledge the MAX232 is only for 5v. I use a
MAX3241. It is a newer chip designed for laptops and palmtops. It has
power saving features, 400khz per transmitter guaranteed data rate, 3
transmitters, and 5 receivers.
> max232 info (there's bunches of other chips, that just the one
> I've heard of most often.)
> sells the MAX232 with the required four caps for $2US
> - j
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