Re: 1ch uart w/ narrow parallell interface...?

From: Jim Granville (no.spam_at_designtools.co.nz)
Date: 11/22/04 

Date: Tue, 23 Nov 2004 09:49:38 +1300

Torbjørn Heltne wrote:
>> It would be useful if you could add a little more detail to your
>> requirements such as speed.
>>
>> Depending on how busy your uC is, you could bit-bang the serial port
>> if the data rate is not too high. We have done this on projects where
>> space and cost were at an absolute premium.
>>
>> It was not clear why you can't use SPI, but if what you mean is you
>> can't use SPI for the serial port, you might use a separate small
>> micro that has both SPI and serial. You talk to the SPI port from
>> your micro and it talks to the serial port.
>
>
> Speed requirements are <= 38400, amount of data max 150cps in each
> direction. I have read some on a few bit-banged serial port
> implementations. Common for all of them were that they were half duplex
> only. I need full duplex. I guess it is absolutely possible to achieve
> that but I think I prefer a hardware solutiuon anyway.

The smallest Std UART with a narrow parallel BUS is the 2691 from
Philips. Comes in 24 DIP and SO packages.

> I'm not too sure why I don't want to use the SPI-interface for asynch
> SCI communication. You're more than welcome to give me reasons to do it
> that way.

You may find that a small uC with SPI+UART, is cheaper/smaller than a
small UART. Philips have tiny LPC91x series uC devices as small as 14
pins, with UART and SPI ports, so you can add as many Duplex UARTS as
you want....

-jg

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