Newsgroups: comp.sys.transputer
From: davidb@ndl.co.uk (David Boreham)
Subject: Re: Is it feasable to implement a software UART on a T225?
Organization: Network Designers Limited
Date: Thu, 11 Aug 1994 09:08:20 GMT
Message-ID: <CuD5Dw.ADH@ndl.co.uk>

In article <174@autro1.UUCP> teig@autro1.UUCP (Oyvind Teig) writes:
>DUART IMPLEMENTED IN OCCAM IN T225 - FEASABLE?
>
>I am looking at implementing a (double) UART in occam in a T225.
>The transputer will in addition to being a DUART, handle the serial
>line protocol, and do some other minor A/D etc.
>
>I consider an UART software to be fairly easy, the way I'm thinking of
>doing it is to (over)sample an input-port at a constant speed, independent
>of baud-rate, and note the time of each transsition. Later on, in another 
>process, I will extract the bits, knowing the speed, also filter a little. 
>The reason for all this is that I must implement auto-baud detect, and 
>*use* the first character received - so a hardware UART is impossible(?)
>to use.
>
>Q1.
>Is this possible? I'm planning on no smart programming, just standard occam.
>I need a WHILE loop, ALT with control input and timed input.
>

Yes. It's been done several times by various people.
I think someone had 8 channels at 9.6K going on an M212.

>Q2.
>How far can I strecth it? Sampling every 50 uS?
>

Hmm. My first thought would be to sample at 16X the
baud rate, like UARTs do. Why do you want to sample
at a baud-rate independent rate ? Sounds like you're
making work and trouble for yourself.


