Re: [Sdcc-user] Setting up and sending serial messages

[Jean-Paul <tch...@fr...>]

On Mon, 20 Jun 2005 19:08:05 +0200, Gernot Fink <g....@gm...> wrote:

> On Mon, 20 Jun 2005, J S wrote:
>>
>> Yea, I would've used one of those LCDs, but the
>> project I'm planning on doing is going to require
>> quite a few pins from the microcontroller that is not
>> just for LCD.  Since the 2051 only has 20 pins, it
>> makes adding other components to the microcontroller
>> with a LCD that uses half of the available pins a bit
>> difficult.  Thats why I went with the serial LCDbug.
>
> Use an 4094  8bit shiftregister to connect the Display in 4-bit mode.
> This need 3 pinns.
> You can reduce the pins with a RC for strobe.

You can use a 74HC595 as well.
You can cascade as many devices as you want with the same three pins.

>
> Or a bit expansive use a PCF8574 IIC-Portexpander. This use 2 pins.
> You get 8 bidirektional portpins. One or 2 of them are free after =20
> connecting the
> Display.
>

You get for the same price an interrupt capability on all eight pins!
Use that only if you really need in/out pins. The I2C overhead could be =20
too big for the 2 or 4K flash (89C4051).

Jean-Paul

--=20
NEVER jump into a LOOP!