[Elecraft] Auxbus driver

[Jeff Stai WK6I]

At 07:57 PM 9/9/2003, Jack Brindle wrote:
>On Tuesday, September 9, 2003, at 05:04  PM, Francis Belliveau wrote:
>
>>The possibility of propagation delays causing trouble is another  
>>issue.  I
>>would very much like to hear from Elecraft on the possibility that
>>propagation delays may cause problems.
>
>You have.
>
>The AuxBus is a bidirectional bus, meaning that data flows both  
>directions on a single link. It is a one-wire bus, without a direction  
>signal. The direction of the data is determined by the protocol, and  
>the bus participants must be fully cognizant of, and participate in all  
>data transfers, whether they are the target or not.
>
>This means that it is not at all easy to design circuitry to extend the  
>bus. To make things worse, delays in the data appearing on the bus can  
>cause problems in the operation of all devices in the system.
>
>In short, officially, it is a bad idea to extend the bus for  
>significant distances.

But perhaps not impossible... a bridging device can do things to make 
distant devices appear local; i.e., the bridge makes sure the physically 
local see responses from the physically distant in a timely manner. Like this:

K2 Control----Auxbus Bridge=====(longpath)=====Auxbus Bridge----KAT100

For example, the data from an information request may be stored locally by 
the bridge in anticipation of being asked for it, thus avoiding the round 
trip delay.

The catch is that this is usually very complicated and tricky, and requires 
an intimate knowledge of the protocol and of the devices that are or may be 
attached.

On the other hand, it could be fun to figure it out...;-) - jeff wk6i



--
Jeff Stai               jds@twistedoak.com
Twisted Oak Winery      http://www.twistedoak.com/
Rocketry Org. of CA     http://www.rocstock.org/
Amateur Radio           WK6I