Rikard Bosnjakovic wrote: > On 4/20/07, Richard Seriani, Sr. wrote: > >> I'm new to PICs, but maybe the information in Table 17-4 of the >> datasheet, particularly parameter 32 (oscillation start-up timer >> period) will help? > > Except for the confusing datasheet (it's sometimes referring its > internal oscillator as external, and you have no idea which is which), > I think this table will help. According to it - and if I parse it > correctly - it's around 30 usecs. And since the timer won't start > before the user presses a button, it's perfectly in limits. I mean, > noone will be able to turn the device on and within 30 usecs press the > button. It can take a second or two for the oscillator to come all the way up, but it's not like you're going to damage the PIC if you enable the counter early. I think they just want you to be aware that you can't just turn it on and expect it to instantly snap into action counting time accurately. The T1OSC consumes very little current, you could probably just let it run all the time even when sleeping if you need to be able to measure time as soon as you wake up. Yeah, the datasheet is pretty confusing about INTOSC vs INTRC etc. In fact they are downright ambiguous about it and admit so as a disclaimer in some datasheets I've seen. The two-speed startu, failsafe and associated speed switching are also somewhat confusing, but you will figure it out as you go along. You don't have to really concern yourself with all the failsafe stuff right now. T1OSC is completely seperate from INTOSC/INTRC. They can be turned on and off independantly. TMR1 won't count until you enable it, regardless of T1OSC running. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist