Picaxe 20M Timer1 available?

[rhaseman]

Several years ago Hippy developed code to implement a real time clock in software for a picaxe 18X. That code depended on the availability of the Timer1 module on the chip. Can anyone confirm if this approach could be used with the picaxe 20M - basically, is the timer1 module available on the 20M and is it not used by any of the picaxe functionality.

Hippy's webpage for this rtc is http://www.hippy.freeserve.co.uk/picaxert.htm.

What I am trying to do is implement a event timer able to measure time periods from 0 to 24 hours with an accuracy of a few minutes. Any ideas or suggestions would really be appreciated.

Thanks

Rick

 

[hippy]

You probably can do the same on the 20M. Whether doing so affects PICAXE functionality I cannot say off-hand, but if you don't use any commands which require use of the timer there probably wouldn't be any issues.

A bigger potential issue is the accuracy of the on-chip oscillator. With +/-2% accuracy, over 24 hours it may be +/- half an hour out. In practice you would likely see better accuracy than that but it's not guaranteed. Using CALIBFREQ can help improve things.

The issue is resolution; needing 1 minute accuracy over 1440 minutes ( 24 hours ) means having a clock reference accurate to 0.07%

 

[westaust55]

And further to hippy's response, if you look at PICAXE manual 2 Appendix 4 ( page 251 in V7.0) there is a table of Possible Conflicting Commands.
Timer and Servo both use Timer1.