[En-Nut-Discussion] Ethernut 5.0 Schematic Preview

[Harald Kipp]

duane ellis wrote:
>> Me too, but the available board space is against this bulky connector. :-)
>> I considered using the new 38-pin AMP Mictor. 
> The Mictor is only used for the ETM macro cell - you don't want to 
> bother with that.

Obviously we Germans are too conservative in technical things. ;-)
IMO, the Mictor will become a JTAG standard connector sooner or later. I 
prefer to use long term stuff than inventing a new connector.


> I would seriously find a way to make the 20pin arm connector work, maybe 
> not 0.1 centers

That would be a new connector, even if the pins are the same.


> but - another tighter one? The point being - all pins should be on one 
> connector. Not two connectors.

That's a misunderstanding, caused by unclear schematics. Sorry. JP2 is a 
2mm grid jumper block, not a connector. It allows to

1. Enable boundary scan (5-7)
2. Route RTCK to the spare pin 8 (3-4)
3. Route NTRST to the spare pin 8 (1-2)
4. Erase internal flash (7-8)

In Rev-C I moved NTRST to pin JP2-2 and added NRST to JP2-1, which 
additionally allows to internally connect NRST and NTRST (see SAM9XE 
datasheet Feb-08, chapter 46.2.4. (Not really a problem because of the 
flexible power management, but at no cost.)

I do have SAM9XE samples and we still hope, that Atmel will provide 
enough chips for the first production. But if all this fails, we can 
still use the SAM9260, in which case JP2 allows boot mode select.

> 
>> Is there any problem using an adapter? Similar to
>> http://www.ethernut.de/en/hardware/turtelizer/index.html
>> (The PDF in chapter "JTAG Adapter")
>>
> Yea, that could work - however I like the idea of 1 connector.
> And besides, this means everybody will need a special cable just for 
> this board.

We may include the adapter in the starter kit. However, only one signal 
will be available, either NTRST or RTCK. Or we may use an additional 
jumper to switch pin-2 between GND and RTCK. Not the best solution to 
remove the GND return near TCK, but should work fine with short cables.

> Yuck.

Sigh. ;-)

Harald