What is the best way to have additional serial ports on AVR?

[binnyr]

Hi:
I am currently designing a board around AT90S8515. This microcontroller has one serial port built-in.

I require four(4) additional serial ports on this board! What is the best way to have get this done without too much cpu usage? (software uart is ruled out).

Thanks in advance.
Regards
Binny

 

[ramesh]

Hi

Use NS16C550 (UART) or it's derivatives for multiple NS16C550. It has 16 byte FIFO which reduces overhead on microcontroller interrupt rate. It supports upto 110kbits/sec baud rate.

 

[CADDevil]

Hello,

Maxim is manufacturing SPI/Microwire UARTs MAX3100 and MAX3110(with integrated RS-232 driver/receiver and internal capacitors).
Maybe you can try to use them. I think that Maxim can send you some samples