Cheap, small quad UART needed

A small microcontroller would do it, using soft UARTs. Something like an ATMega48. 3 UARTS at 38K4 is probably just about doable at max clock rate with careful coding.

Or Two Philips LPC2101's ( 2 HW uarts each) , or one ( 2 HW + 2 SW UARTS). Note that creative use of the SSP port can provide an additional hardware TX UART

The Renesas M32C cpu family has five uarts per chip, each of which can be configured in one of six communications modes, one of which might be usable as an SPI port. The chip is kinda big, though - 100 pin tqfp, and starts at $23 at digikey.

The r8c family is a 20-SSOP at $4 for two uarts plus i2c each.

That is indeed not what I was looking for :-) My ideal UART looks like 20 pins max, maybe a 32 pin TQFP for $5 max.

Meindert

Looks like an interesting candidate, still a lot of surplus pins/signals I don't want/need. Thanks,

Meindert

at max clock rate with

Thought about that too. I'll investigate that more.

Thanks, Meindert

LPC2101 gives 2 UARTS for about $2

Renesas microcontrollers tend to have many UARTS. Check the medium models from M16C family.

LPC2300 from NXP have 4 UARTs, LPC3180 has 7 UARTs, STR910 has 4 UARTS

s

be

It is possible to implement up to 4 UARTs in some of the Cypress PSoCs You could also implement an SPI interface. If the serial ports do not hav to be active concurrently, it would be possible to use fewer UARTs an multiplex them to different pins on the IC.

-Aubrey

"Meindert Sprang" skrev i meddelandet news:45f92098$0$22652$ snipped-for-privacy@dreader14.news.xs4all.nl...

AT91SAM7S321 in QFN-64 (AT91SAM7S161 when available)?

3 x H/W UART and you can probably use the SSC as H/W support for 4th UART. All UARTs including SSC has DMA support.

--
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

I seem to recall this from Meindert, earlier: "My ideal UART looks like 20 pins max, maybe a 32 pin TQFP for $5 max." ^^^^^^^^^^^ ^^^^^

Jon

But ideal and real can be worlds apart, of course :-)

Meindert

If you want an 8-bit parallel interface on one side and a Rx and Tx line per port on the other, you're at 16 already. Some address lines for selecting the internal registers, CS, power, and ground and you're past 20 pins. You might be able to make it in 32 pins and have some hardware handshake pins.

No, I wanted an SPI interface.

Realy nice product indeed. This goes for $2.50 for 1 channel and $4 for

2 channel device in single quantity at Digikey.

Seems this is exactly what OP is searching for.

Thanks for the link.

I don't see where you got much discussion on CPLDs. There are any number of CPLDs in small packages. However, they don't typically have as small pin counts as you would like, 20/32 pins. They tend to start around 48 pins for CPLDs, but a 48 pin TQFP is a pretty small device. Most CPLDs will be register limited however. To implement 4 UARTs and an SPI interface, you will need to define a protocol for the SPI interface and it will require most likely a command word to be written for each byte transferred in either direction. I estimate about 24 FFs for the SPI including the state machine (off the top of my head). You will need some 20 FFs per receiver and another 24 per transmitter if you want it double buffered. The baud rate generator can be in the range of 8 to 16 FF. So this totals some 200+ which puts you in a 256 MC CPLD. These tend to be a bit pricey and are typically not available in a small package. So your MCU approach is likely to be the best.

There are parts that can do this job easily, but you will need to go with a BGA to even get close to a small package.

I have seen FPGA vendors discuss how there is little demand for higher density devices in smaller pin count packages. I often wonder if that is really the case or if it is really just a matter of them wanting to pick the low hanging fruit rather than to compete on lower margin devices. They don't have to sell very many $1000 FPGAs to bring in more profit than the $4 parts. But I know I have had applications for small FPGAs in low pin count packages.

Have you looked at Philips / Exar ? Don't forget to include 2 x Dualchannel uC as they may still be cheaper than a Quad solution. If this has to be 'no shortcuts' with full duplex, full buffering, and handshake, then it's going to push a single uC, and for CPLDs you'll also find it hard to source one that is going to compete with 2 cheap uC, in $ and PCB area. Something like the AT89LP216 from Atmel, at ~90c/10K, will do 1 Chan in HW, and probably 1 more in SW, so that's ~ $2 - the new SiLabs C8051T600 has i2c, no SPI, but thats getting under 50c for a single channel. most likely CPLD,resource wise, would be the Lattice MachXO,but they start at

100 pins..

-jg

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Both are 9 x 9 mm, whats the big deal ?? It'll do the job, and it is in the price range.

--
Best Regards
Ulf Samuelsson