[En-Nut-Discussion] Hardware Failure

[Harald Kipp]

Hi Brad,

The Ethernuts 1.3-Rev-F are equipped with LM1086 regulators,
which can take max. 20V input. The rectifier bridge in front
of the regulator takes at least 40V. 16V will not damage the
board.

The reason for using lower voltages is heat. Ethernut 1.3
needs about 150mA, independent from the input voltage. With
16V this results in 2.4 Watts, of which 1.65 Watts had to
be taken by the regulator, getting it noticeable warm.

Actually 8V is sufficient to get Ethernut running. 1.4V
are dropped by the rectifier, leaving 6.6V for the regulator.

The best thing you can do is, connect a PC to the serial RS232
port and use Hyperterm or a similar terminal emulator and
set it to 115200 Baud, 8 data bits, 1 stop bit, no parity and
no flow control. Switch on the Ethernut and hold down the
space bar on the PC keyboard. We ship Ethernuts preloaded
with Basemon, which automatically tries to determine the
baudrate by scanning for space characters. Make sure, that
your keyboard repeat rate is not too slow, otherwise toggle
the space bar as fast as you can. :-)

If Basemon is unable to determine the baudrate, it will
automatically start at 38400 Baud. In this case, modify
the baud rate setting and watch for the things that appear
in the terminal emulator.

Basemon should start even with broken RAM and broken
Ethernet. Unfortunately the latest version doesn't
work without 32kHz crystal. If this crystal is not
working within 1 minute after switching on the board,
it is broken.

In general it is difficult to comment your observation
on the clock signals. It depends very much on the
scope, cables, tip etc. Typically, if it's swinging,
it's working.

If you already reprogrammed the board, install the Ethernut
software, if not already done. You will find the Basemon
hex file in the bin directory. You can use any programming
software for AVRs. The serial port programmer, that comes
with the starter kit, works with uisp for Linux and Windows
as well as AVR Studio for Windows, in case you prefer a GUI.
With ImageCraft, you can use the build in programming software.
Set it to STK500.

More infos are here
http://www.ethernut.de/pdf/enhwm16.pdf

OK, this is a lot of standard blah blah you may know already,
but I took the chance to describe these things in detail for
the mailing list.

Some more:

In case your board is really broken, we will of course
replace it. Please contact your dealer, if you didn't
purchased it from us directly. We will arrange with them.

If you decide to try to replace any part yourself, go
ahead. You are not losing any warranty.

Quite often specially the RTL8019 equipped boards get
damaged by ESD. Please take care when handling the board.
Never pass it from one person to the other. Anyway,
things like that could happen and we will not leave you
standing in the rain.

Please let me know, what Basemon reports.

Regards,
Harald