[En-Nut-Discussion] PORT E (Ethernut 1.3)

[Harald Kipp]

In a first attempt I'll quote a reply I sent recently to a customer. May be this is sufficient. If not, please come back to me.

Here is my post:

For Ethernut 2 I can find this one
http://www.ethernut.de/en/hardware/enut2/ports.html
It is quite similar to 1.3, except for UART handshake and PB4 (Dataflash
CS) used on Ethernut 2, but not Ethernut 1.

You can use PB, PD and PE, except

PE0, PE1 (UART)
PE5 (IRQ)

As you already found, this gives 24 - 3 = 21 available ports.

Then, of course, you can use PF0-PF3.

And you can use PF4-PF7, if you disable JTAG by setting the JTD bit in
register MCUCSR. However, you need to make sure that your attached
hardware will not interfere when using JTAG. As long as you are using
the SP Duo programmer, you may then use SPI instead of JTAG. SPI
programming uses the UART lines and will not interfere with JTAG.

If you still need JTAG: As soon as JTD is set, you need to press the
reset button to enable JTAG again.

Address and data lines may be used too, but that becomes quite tricky,
because your running program needs them too.


Harald