Hi Ernst

If you use, a hitachi HD44780 based standard LCD, you can interface it with
only 3 i/o from the pic, and then shift the data into a shiftregister (i.e
4094) But then you will not be able to read from the LCD, however, if you
only want to write to the LCD this works fine.
I have a system running with 74HC922 and a LCD like I described.
Mail me if you want further info/help.

Best regards
Henrik Nowak
hno@post3.tele.dk

-----Oprindelig meddelelse-----
Fra:    Ernst Aardal [SMTP:ernst@AARDAL.COM]
Sendt:  10. oktober 1999 23:30
Til:    PICLIST@MITVMA.MIT.EDU
Emne:   Re: Stepper-controller

Thank you, Keith Causey!
Regarding the output, yes I will use this pulses to run a larger amplifier,
might
be a L297 and L298 or even Powermosfet and a Ericsson chipset, I have made
several of this earlier.
Then do you have any idea how to connect the keypad and LCD display.
I thought of using a 74C922, this is a 16 key encoder with 4 bit data
output
and a data available and a enable input. So this will need 6 of the pic's
i/o
then the lcd will use 6 i/o lines, this is 12 of the 16x84's 15 i/o.
But I have seen in a Basic-stamp configuration that they are using the 4
databits and the data available at the 74c922 and the RS terminal at the
lcd
common.  Any Idea about this?
Ernst

Keith Causey wrote:

> Hello Ernst, I have worked with driving stepper motors and with 16C84's
but
> not together. However, armed with the knowlege of the capabilities of the
> 16C84 and the operation of stepper motors there will be no problem
getting
> your project to perform in the manner you indicate. In order to count to
> 2,000,000 you will need to concatenate 3 of the 8 bit internal registers
of
> the 16C84 into one long 24-bit register. You do this by observing the
state
> of the carry bit after you add a 1 to any 8-bit register. When you
subtract
> a 1 its significance reverses (becomes a "0" to indicate a borrow) and
you
> must subtract 1 from the next higher register. When you say that you are
> going to output step and direction pulses it seems to indicate that you
are
> using the PIC to control a stepper motor driver chip as a stepper motor
is
> incapable of handling this information directly. Is this the case? If so,
> what kind of chip is it?
> Keith Causey
>
> > I am a newstrater in pic assembly but here is my scope:
> > I am going to make a controller for one steppermotor that shal run for
> > a number of steps:
> > -I am going to use a 4x4 keypad
> > -I am going to use a 1x16 lcd that displays the number that I am
keying.
> >
> > -The number will be from 0.01 to 9999.99, the largest number of steps
> >    generated wil be 2,000,000
> > -I am going to output step- pulses and dir-pulses  on  2 pins of the
> > chip.
> >
> > Does anybody think  that  I can use a 16F84 for this project?
> > Has anybody done this before?
> > Is it possible to store this large number in a 16F84 or C84?
> >
> > Ernst