Re: newby needs help
| Newsgroups | gmane.comp.hardware.texas-instruments.msp430.discuss |
|---|---|
| Message-ID | <[email protected]> |
Al, Thanks. That matches my experience. The DCO MOD makes the timing quite inconsistent. With the 8 MHz DCO calibrated setting I can see the pulses vary. There is a complex relationship between the DCO dither and the PWM timer settings, so not adequate for precise work. Which is why I've been using ACLK w/ the 32 KHz xtal. Still very impressive for such a cheap piece of silicon. It's quite hard to get anything off chip to switch that fast. The fastest pulse I can get switching a 2N3904 is 200-250 ns. And it takes a lot of drive to get it to switch on or off in 100 ns, so I backed off to keep things from getting too hot. Ive been looking for a low cost transistor w/ a higher fT, but haven't ordered any yet. Interesting tidbit. The 2N3904 has a nice clean ramp up and down whereas a 2N2222 has rather wiggly rise and fall slopes. It's quite a remarkable difference. I'm concerned about the pulse spectrum, so the 2N3904 is much preferable. It has a sinc(x) transfer function with the first zero at 8-10 MHz. Have Fun! Reg ------------------------------------ Posted by: Reginald Beardsley <[email protected]> ------------------------------------ To unsubscribe from the msp430 group, send an email to: [email protected]