external oscillator with demo board?

ionymous

I'm using FullDuplexSerial on my demo board successfully at a lower baud rate (19200) to receive data from a PC. I'd like to go higher (115200).

I've gathered from the forums that at a higher baud rate I might need adjust my baud rate because the props internal oscillator is only accurate to within 10%.
I've also gathered that a better more reliable method is to use an external oscillator.

I've searched the forums for 30 minutes but I'm not seeing any examples.
Can someone help me here?
How would you use an external oscillator on a prop demo board to achieve an accurate 115200 baud rate with FullDuplexSerial?

Thanks for any help
Ion

Phil Pilgrim (PhiPi)

I'm not sure where you got that 10% figure. It's wrong. With the supplied crystal, you should have no trouble achieving the needed accuracy at higher baud rates.

-Phil

ionymous

Ah.. I have re-read some posts and now see the clock inaccuracy comments refer to the internal clocks, RCFAST and RCSLOW.
I'm still very much a novice here and didn't really understand the meaning.
Now I think I get it... the demo board has a external oscillator on it. So as long as my code uses that, I'm good to go.

Thanks

Phil Pilgrim (PhiPi)

Well, saying "external oscillator" when referring to a crystal is a common misnomer. A crystal is better described as a resonant element that's used with the Prop's internal crystal oscillator. There are such things as external oscillators, but they require their own power source and output a square wave on their own. Such oscillators can be used with the Prop; but, in most cases, it would be a costly extravagance, given the Prop's internal oscillator.

-Phil