Nope, the PAUSE command in the BS2 is not very accurate. The 'clock' on a BS2 is based on a 'resonator', which are not very accurate -- may gain or lose minutes in a day. On the other hand, a 555 timer is REALLY inaccurate, so the BS2 Pause command is better than a 555.
If you REALLY want accuracy, go with the 1302 with an external 32Khz crystal. This gives you seconds per day accuracy.
And of course, there are 10 Parts Per Million crystal-based timers, but these take more power (10 mA).
It should be. Again, accuracy is usually stated in how many seconds off it is. Your 60 seconds could be 58 or 62 seconds. You'd have to do an experiment to find out.
In regards to a 555 timer... your accuracy is a function of the capacitor and resistor tolerances (and temperature drift) that you use to setup the 555, correct?
Yes, the assertion that a 60 second PAUSE with the BS2 could be as low as 58 seconds or as much as 62 seconds is way off base. That said, at the same temperature the behavior will be consistent, so you can tune your program accordingly.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ Jon Williams Applications Engineer, Parallax
Dallas, TX· USA
D'OH! I'm so sorry, Jon, I did not mean to be way off base.
Just so people know, Jon is the guru with·Parallax.· Occasionally I get things wrong -- as in this case. I still recommend doing a test to find out just how accurate the PAUSE is -- I merely know it is insufficient to do a Time-Of-Day clock. More than that I should not say, as I have NOT done such a test myself.
Matthew
Posts: 200
Comments
If you REALLY want accuracy, go with the 1302 with an external 32Khz crystal. This gives you seconds per day accuracy.
And of course, there are 10 Parts Per Million crystal-based timers, but these take more power (10 mA).
Dave
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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA
Just so people know, Jon is the guru with·Parallax.· Occasionally I get things wrong -- as in this case. I still recommend doing a test to find out just how accurate the PAUSE is -- I merely know it is insufficient to do a Time-Of-Day clock. More than that I should not say, as I have NOT done such a test myself.