Command dependencies upon on-chip timers

[rolfi@tisco.no]

Hello,
I am trying to use a 20X2 in a project which will involve lots of the many commands involving the 20X2's internal timers. Many of these commands might intefere with ea other ( different serial comms, count, pwms, play, servo, pulse , pause, timing, etc. ), and even if I have have tried to study the manuals and search the forum, I find it hard to obtain a clear picture.. It would really be great to have some kind of documentation showing which of these commands are using which of the 4 internal timers of the 20X2/PIC18F14K22 chip. If anything like that exists, it would certainly be much appreciated!

 

[kranenborg]

Hello Rolfi,

I once asked a somewhat similar question and I got the following reply: http://www.picaxeforum.co.uk/showthread.php?17815-18M2-touch(16)-command-and-timer1-use

Best regards,
Jurjen

 

[westaust55]

Also have a read of PICAXE manual 2 Appendix 4 which covers conflicts between some commands where the same timer or critical timing (such as serial comms) occurs.

 

[rolfi@tisco.no]

Many thanks to kranenborg and westaust55 for you answers! I am aware of , and have looked carefully through Appendix 4 in manual 2, but still, I struggle to get a clear picture of this. It is easy to agree that certain tasks - like sercomms -gotta have 'a certain' priority over - let's say a timer overflow interrupt.
On page 267 the manual tells us this: "The user program must work around this limitation of the microcontroller." Fair enough, but then I myself - as a user - need more precise information abt how things are connected, and what is going on. The 20X2 has 4 timers, timer0 - 3 . Timer0 is not mentioned on p. 267, and if I want to use the -seemingly independent - timer3 for timing purposes, I see no preload or interrupt option for that one. While timer1 has this, but interferes with 'servo..'. and, is of course disturbed by sercomms.. and what else?
Well, I am sorry for being such a slow learner, but as there are lots of threads abt these issues, some clarification might be very welcome by many ...
What commands/processes are using which of the timers, and in what way? Technical? Hippy?

 

[inglewoodpete]

The description of SetIntFlags in Manual 2 refers to bit7 of the flags byte as being associated with Timer0 so Timer0 must be the one creating the Timer overflow interrupt. Also, refer to the SetTimer command.