16f876 dual serial asynchronous link?

[Yoong Ping, Lim]

Hi,

i need to have two asynchronous link using 16f876 but it only has 1 usart
hardware?

any recommendation?

thanks

 

[Josh]

Yoong Ping, Lim wrote:

Hi,

i need to have two asynchronous link using 16f876 but it only has 1 usart
hardware?

any recommendation?

thanks

If your 2 async links can be different speeds, just wire both up in
parallel, and switch the BRG from one speed to the other to switch
between serial devices.
As long as there's sufficient difference between the two speeds, the
two devices connected won't see the data destined for the other. From
memory anything more than about 10% difference is pretty safe.
Last time I did this on a '876 I was switching the usart between 1200
and 38400bps without any problems. The trick is finding a crystal that
will allow the baud rate generator to approximate your two baud rates
accurately anough.

Josh

 

[David Wilson]

"Yoong Ping, Lim" <wincluster@gmail.com> writes:

i need to have two asynchronous link using 16f876 but it only has 1 usart
hardware?

any recommendation?

Try hanging a MAX3100 off the SPI port.

http://www.maxim-ic.com/quick_view2.cfm?qv_pk=1731
--
David Wilson School of IT & CS, Uni of Wollongong, Australia

 

[CBarn24050]

Yoong Ping, Lim wrote:
Hi,

i need to have two asynchronous link using 16f876 but it only has 1 usart
hardware?

any recommendation?

Hi, it's quite easy to set up multiple uarts using software (bit banging).
Obviously this takes up quite a bit of the available processing time, but this
may not be a problem for your application.