Keith Causey email (remove spam text)
Hello again Ernst. I have never interfaced an LCD display to anything so I
can give you no help there. The keyboard on the other hand is simple. If it
is 4 x 4 and wired such that there are 8 lines, 4 from the rows and 4 from
the columns, then the interface can be done with an 8-bit port. I have not
used the 74C922 but from your description of the peripherals and the
resources they require you may not enough pins if I understand the following
correctly. You have:
6 pins for the 74C922 and
6 pins for the LCD display and
2 pins for the stepper motor controller.
The 16C84 has 8+4 i/o lines and an RTCC line that can, in certain
situations, be used as an input. Conservatively you have a 2-pin deficit. I
will need the data on each of the chips you are working with to tell you
more. You may email them to me if you wish.
> Thank you, Keith Causey!
> Regarding the output, yes I will use this pulses to run a larger
> 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
> and a data available and a enable input. So this will need 6 of the pic's
> 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
> common. Any Idea about this?
> Keith Causey wrote:
> > Hello Ernst, I have worked with driving stepper motors and with 16C84's
> > not together. However, armed with the knowlege of the capabilities of
> > 16C84 and the operation of stepper motors there will be no problem
> > 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
> > the 16C84 into one long 24-bit register. You do this by observing the
> > of the carry bit after you add a 1 to any 8-bit register. When you
> > a 1 its significance reverses (becomes a "0" to indicate a borrow) and
> > 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
> > using the PIC to control a stepper motor driver chip as a stepper motor
> > incapable of handling this information directly. Is this the case? If
> > what kind of chip is it?
> > Keith Causey
See also: www.piclist.com/techref/io/steppers.htm?key=stepper
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