Micro choice with 4 UARTs

I suggest you take a look at the Renesas H8 series. The documentation is quite good, and a free C/C++ compiler (gcc) is available. While the H8 series might not qualify for "low cost", it definitely has features enough.

At that baudrate you could easily do it in software without too much trouble. If there are other timing constraints that preclude this, maybe use a cheap slave PIC/AVR as an intelligent UART peripheral. Either route is likely to be cheaper & more flexible than constraining yourself to the few parts with enough hardware uarts.

Maxim has a SPI uart

Kasper

You may find some relevant comments in this thread about micros with UARTs:

And one piece of bit bang code could run all serial ports running at the same baud rate.

Ian

Hi Iain,

software implementation of some of the UARTs is a given for a low cost device, one with 4 HW UARTs is much more expensive than one with 1 UART and 3 in SW. You mentioned a few hundred bytes a second, well that would be continous operation if using 4800 Baud, gives you max 480 bytes/sec.

What is different about the one UART? Guess you want to have that one in HW. There are some really nice LPC915/LPC916/LPC917 devices from Philips. They run from an internal oscillator (7.373 MHz) and all have a HW UART and 2 also have an I2C in hardware.

more information can be found here:

They come in 14/16-pin packages with 2k Flash and 256 bytes RAM. As the core is a 2 clock per instruction cycle, it is about as fast as 4 MHz AVR or a 14.7 MHz PIC or for that matter an old 8051 running at 44 MHz.

An Schwob

snipped-for-privacy@hotmail.com wrote:

Well the one that immediately springs to mind is the H8S/2378

Internal memory is on 16bit wide bus

Various compilers support them I am biased towards GNU for them.

..or even different baudrates with a timer interrupt running at twice the highest rate, but this gets a little more interesting...

A slave PIC/AVR is probably cheaper though

What else does it have to do ? The spec is simple, but the devices you've metioned are large, so there is probably something else missing. For the tasks above, you could choose a faster, small uC, like the C8051F330, or the new AT89LP2052/4052. These are 25/20 MIPS, and have the 80C51 core that handles bit-level uarts very well. The LP2052 also has a double buffered SPI, so can slave properly to other uC. When doing bit-level Serial, you have tight time constraints, so it is best to focus on that, in a smaller controller.

-jg

You Might get that many with a Cypress PSoC

Cypress PSoC CY8C29466 is around 5 USD in small quantities and it can provide 4 UARTs.

But in a production line the programming part can be expensive in time

Kasper

The forthcoming ATmega640 is rumoured to have the same peripherals and should be pin compatible and cheaper (when available)