On Fri, 22 Apr 2005 17:06:03 -0500, Glen VanMilligan <glenv@vpcvalley.com>  
wrote:

> Can't seem to read in on com 1, but only transmit out on Com1.
> Any ideas?
> I put a maxim 3222 as the interface, it seems to work ok, but when I  
> take the
> recv output from the Maxim chip to the D31 on the Connector, it pulls the
> line low.

Err... I think you can't do what I think you're doing.
COM1 is on J12 - called 'PINKO_RXD' and 'PINKO_TXD' (there's also a  
pinko_RTS line).
(pinko, because the connector's errr, red, on TCL builds :)

The levels on J12 re 3.3V, 5V tolerant. If you want to pick that COM port  
up on the backplane connector, you'll need a variant version of the  
Xilinx. no big deal - you can do it yourself (the free webpack tools from  
Xilinx are pretty usable), or ask one of us to do it, if you can't face  
that.
However, until you stop the Xilinx doing the buffering, you'll not be able  
to use the receiver on the backplane.

Steve

(Balloon3 meeting tomorrow at Cambridge engineering department. Time to  
unstick the remaining disputes, and get on with the job in hand. It's all  
rather more complicated than Balloon 2.xx, when I just did what I damn  
well liked :)