[En-Nut-Discussion] Re: Re: Adding LCD, Keyboard,...

[Harald Kipp]

There are enough expansion port pins. Ethernut 1.3 just
uses PORTE Bit 5 for the Ethernet Controller Interrupt.
This can be optionally switched to bit 6. See schematic
page 3.

All other CPU ports are available. Except PORTA and PORTC,
of course, as they are used for the address/data bus.

Also note, that the upper four bits are used by the
JTAG connector, but software can switch it off. In
any case please check the ATmega128 datasheet.

It's hard to tell about performance, not knowing what
your requirements are. Specially for the graphic LCD.
Take in account, that the ATmega128 on Ethernut is
running at 14.7465 MHz. That's almost equal to the
number of instructions per second. For example, an RGB
display with 256 colors and 320 x 160 pixels requires
50 kBytes for a complete refresh. If that should be
limited to, let's say, 10% CPU load, there are just
28 cycles left for data transfer and the next question
is: Where does this data come from?

On a B&W display the situation is much better, of course.
And if you do not need a complete display refresh, but
simply draw a few bar graphs with some text, the ATmega128
will become bored.

Btw. TCP over Ethernet typically doesn't require much CPU
time.

Harald

At 11:05 22.02.2006 +0200, you wrote:
>With keyboard, I mean 12 button. One 5V and one ADC input is enough for
>analog keyboard. (Don't want a matrix keyboard) So I need :
>
>8 IO pin for LCD data(I don't know but maybe Data lines can be used)
>X other pins for LCD (including 5V, GND, EN vsvs)
>2 ADC
>1 PWM
>
>Just I'm asking is there enough IO expander pins. Please tell me why I can't
>use Ethernut 1.3G. Not enough pins, or performance