[En-Nut-Discussion] device location in memory

[Harald Kipp]

Hi Dark,

the ATmega's external address/data bus can be activated
or deactivated. With Nut/OS it is activated by default,
but may be deactivated by the application. Please see the
ATmega datasheet on how to do this.

When deactivated, the address/data bus pins are switched
to I/O port mode, PORTA and PORTC, and the memory control
lines to PORTG. You can then simulate the bus by toggling
the related port pins. As an advantage, you may even use
the RTL8019AS in 16-bit mode, which increases the internal
buffer by 8kBytes. Of course, port toggling is slower than
memory mapped access.

Harald


At 19:37 07.05.2006 +0200, you wrote:
>Hello,
>
>  I have a question how to locate drivers (e.g. network driver) in
>internal memory addresses if I  don't use external SRAM and its memory
>mapping.
>The code provided in Nut/Os refer to memory locations where should be
>seen the state of exact device.
>  I have direct connection ATmega with RTL8019AS on address pins.
>  Is it possible to map the 32 registers of ethernet controller to
>internal memory?
>
>Dark