advice needed: simple baud rate conversion

[[email protected]]

Hello,
I have a simple application that requires interfacing a device which tx
data at 9600 baud, and another device that rx data at 115k baud. Have
considered pic but am not sure which one and not all can support the
higher baud rate.

Thank You
Greg

 

[Mike]

Hello,
I have a simple application that requires interfacing a device which tx
data at 9600 baud, and another device that rx data at 115k baud. Have
considered pic but am not sure which one and not all can support the
higher baud rate.

Find any processor that can input at 9600 and then just user a timer
and output 115K on any other port by doing the bit shuffling yourself,
so then you dont need a cpu that has a serial port to do 115K...
You just have to be careful in setting your interrupts and what you
get the processor to do between output bit states, bit of interleaving
and you dont need interrupts even, can be fun doing it that way. I did
one once with 4 lots of 4800 input and one output at 19200,
ie. The UART port was the output and the 4 inputs were bit shuffled
and used a mapping function to ensure I didnt lose any edges, neat stuff.
Oh and there was a pair of hc86's on the front end - as an error/coincidence
flag check, though it never went off to indicate I missed any edge timing...


--
Regards
Mike
* GMC/VL Commodore, Calais VL Turbo FuseRail that wont warp or melt !
* High grade milspec ignition driver electronics now in development
* Twin Tyres to suit most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au

 

[gg]

Hi Mike,
Thanks for the advice. Could you suggest a cheap processor that will do
this? As mentioned I have consdered pic processors but was confused
with the huge number of these devices and the limitations many had in
being able to output at 115kBaud. My main concern is that I can program
the processor without having to buy expensive development kits and so
on. Also the outputting of data at 115kb requires some tricky
programming. Do you have any examples of software that does this?

greg

 

[Mike]

Hi Mike,
Thanks for the advice. Could you suggest a cheap processor that will do
this? As mentioned I have consdered pic processors but was confused
with the huge number of these devices and the limitations many had in
being able to output at 115kBaud. My main concern is that I can program
the processor without having to buy expensive development kits and so
on. Also the outputting of data at 115kb requires some tricky
programming. Do you have any examples of software that does this?

You can do serial in/out with any processor just about if you are
able to 'bash the bits', I might add, you can do that at way above
115K if you really wanted to without much trouble at all.

What do you consider expensive, there are programmers on the net
that have free s/w and recommend h/w you can build yourself for
less than $10. ?

Not tricky at all to output serial, like stopping at a red light and
waiting for it to turn green, same principle just add a counter for
the number of bits, the rest is a sequence of events, do it by hand
for one byte if you like and you'll soon see its trivial. Just get
acquainted with the functions for count, jump, shift etc

Not willing to give my examples as it really depends on the processor,
it would be very easy to get misled and waste time, as you are new to
this I'd recommend doing it from first principles, though sure, you
can find examples on web through google, your time not mine.

--
Regards
Mike
* GMC/VL Commodore, Calais VL Turbo FuseRail that wont warp or melt !
* High grade milspec ignition driver electronics now in development
* Twin Tyres to suit most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au

 

[Andrew McMeikan]

Hello,
I have a simple application that requires interfacing a device which tx
data at 9600 baud, and another device that rx data at 115k baud. Have
considered pic but am not sure which one and not all can support the
higher baud rate.

Thank You
Greg

You could use a z180 processor, not quite one chip solution but you
could still keep it simple and gives you heaps of power if you need to
do any other conversions or buffering.

cya, Andrew...

 

[The Real Andy]

Hello,
I have a simple application that requires interfacing a device which tx
data at 9600 baud, and another device that rx data at 115k baud. Have
considered pic but am not sure which one and not all can support the
higher baud rate.

Thank You
Greg

Use a 16F688. Listen on the UART, bit bash out a GPIO pin.

If you want an easy to get part, then use whatever your local hobby
shop sells. You can always listen on one port pin using a timer and
bit bash out on another pin.

YOu should not need a fast device for this. Most of the bottom end
devices now support at least a 4MHz clock (last time i checked) which
is plenty.

I just had a look at the PIC collection, it is pretty impressive these
days.