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

Nov 17, 2004 10 Replies

Are there any uarts around with a "narrow" parallell interface which can be utilized from a uC w/o a full-blown address/data bus system? I am aware of the possibility of using SPI-type uarts - but for various reasons those are not an alternative this time.



I was thinking about the possibility of using 8-9-10 general IO lines on a uC and I guess I should use an interrupt line as well.



Small footprint, low pin count, smd (of course), low price?



Ideas, anyone?


Torbjørn Heltne

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.

Scott

Hi,

How about a micro with built-in serial. PIC16F628, or PIC16F870 both have uarts.

Luhan Monat: luhanis(at)yahoo(dot)com http://members.cox.net/berniekm "The Future is not what it used to be..."

Speed requirements are

Why not go for the ATmega162. It has two serial ports.

Meindert

I can do without the TWI but need a couple of A/D channels.

Torbjørn Heltne

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

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

Hi,

the LPC915 has UART, 4 ADC channels and 2K FLASH. It is much cheaper than ATmega of the PIC16 proposed and does not even need an oscillator (internal RC)

Schwob

Mmmm... I am alway very sceptic about internal oscillators in combination with UARTS. What do others think? Good/bad experiences?

Meindert

It's rated at +/-2.5% over temperature (and +/-1% at room temperature). That sounds good enough to me if the divider granularity doesn't add too much additional error, especially if you're communicating with something that uses a crystal.

Best regards, Spehro Pefhany

"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

For a single UART, the ATmega48 is a better choice.

Best Regards, Ulf Samuelsson ulf@a-t-m-e-l.com This is a personal view which may or may not be share by my Employer Atmel Nordic AB

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