Linux-Hams archive - July 1998: Re: Baycom problem - comment and question

Re: Baycom problem - comment and question

Duvall, Michael J. (mwl.yxilx@next-computer.ro)
Wed, 1 Jul 1998 13:37:38 -0400

Albert S. Woodhull replied:
>On Wed, 1 Jul 1998, Duvall, Michael J. wrote:
>
>> Someone told me that the UART was used and as a result the Baycom
>> required little CPU time, just the normal UART interrupt overhead. I
>> guess my original fears were correct.
>>
>> I think they call this a bit banger UART. Cheap and DIRTY! Unless CTS
> Note-> ^
>The point is, for sending packets you can't use a U*A*RT. The 'A' stands
>for asynchronous, that is, a form of data transmission in which there
are
>synchronizing start and stop bits framing each byte of data. But a
>packet is a relatively large number of bytes sent as a *synchronous*
>stream, i.e., with no start and stop bits between the bytes of
>data.

We agree! I always thought the Baycom used a software "USART" to transmit
the data.

I made a comment to this effect on the list once and I was told that I
was incorrect. The Baycom used the UART for serial to parallel conversion
the other person stated I assumed that this person actually read the
manual, and knew what he was talking about.

I just looked up the data sheet on the 16550 and as you say it DOES NOT
support synchronous communication. The driver just use the UART as an IO
port.

I am still kind of leery of this approach, If you can recompiling the
kernel while using the modem I would say its OK. I guess I am just
skeptical. I do plan on buying one so I guess I will find out sone
enough.

Mike Duvall
ac4zq