Cheap, small quad UART needed

Meindert Sprang · 2007-03-15T10:29:38+00:00

Hi Guru'sI need a quad UART chip with only RXD and TXD per channel, no handshakerequired, preferable communicating with my CPU through an SPI port.Baudrates in the range of 4800 to 38400 baud. Oh, and it needs to be cheap.I am thinking about a small controller but most only have two UARTS anddoing four in software at 38400 seems quite a challenge to me. So maybe ssmall FPGA/CPLD solution would be in order. But most of all, it needs to besimple, cheap and small footprint.All suggestions are welcome.Meindert

Jonathan Kirwan 19 years ago

Both parts you recommended, I suppose. The "maybe a 32 pin TQFP" is

7x7 mm, isn't it?

You need to ask Mendert this question, though. I was just remembering his comment.

In 100's. I think your proposition is fine, except you didn't point out clearly where it deviated and where I'm sure you already knew it. With the caveat of size and qty included, I wouldn't have said anything at all.

I've read Meindert's posts and I know he knows a lot about what he's doing. So I tend to take his boundary criteria with a fair degree of seriousness, as a starting point anyway.

Jon

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Ulf Samuelsson 19 years ago

The actual package yes, but the pad ring is 9 x 9 mm in both cases. Admittedly, the layout of the 32 pin TQFP is more tight, since you cannot have vias under a QFN package.

Best Regards Ulf Samuelsson

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Ulf Samuelsson 19 years ago

"-jg" skrev i meddelandet news: snipped-for-privacy@e1g2000hsg.googlegroups.com...

And still an AT91SAM7S161 in a 9 x 9 mm seems superior.

3 UARTs + H/W Support for full duplex UART, all w DMA support and SPI in a 9 x 9 mm package.

Best Regards, Ulf Samuelsson This is intended to be my personal opinion which may, or may not be shared by my employer Atmel Nordic AB

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Meindert Sprang 19 years ago

Thank you all for your comments.

My ideal solution would still be a small FPGA but as mentioned, there aren't any with sufficent cells for 4 uarts without having 100+ pins. So I'll go for the small micro solution. The only drawback of that is that I need an ISP facility (connector or pads) for every micro. It would have been nice if Atmel has made the ISP system daisy-chainable.

Meindert

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Jim Granville 19 years ago

We have mentioned the same thing to them :) - but you can share some of the pins, to reduce the total pin cost, and you can also ISP the newest AT89LPxx series, over the 2 wire OCD, as an alternative.

-jg

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DJ Delorie 19 years ago

My latest board has five ISP chips. Most of the lines can be connected together; I only needed separate lines from the main cpu for each reset, and a mux for the Tx lines. So, they all got the programming data, but only one was paying attention.

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