Instant Interrupts - Revisited

[retepsnikrep]

This is my first try with DT interrupts to implement a 4hz timer ticks.

I'm probably being a bit thick but do the instant interrupts preserve all the variables and return to exactly the same place in program after execution?

Also i have some serin2 code that i don't want interrupting, i can't find the command that enables/disables the interrupts temporarily?

	SERIN2 Bcm, 8276, 250, Main, [WAIT($87), STR BCM87\11]	'Receive $87 (12) byte data packet on BCM Bus

I don't want the above interrupted. ? Thanks

[Darrel Taylor]

I'm probably being a bit thick but do the instant interrupts preserve all the variables and return to exactly the same place in program after execution?

Yes it does.

Also i have some serin2 code that i don't want interrupting, i can't find the command that enables/disables the interrupts temporarily?

    INTCON.7 = 0
	SERIN2 Bcm, 8276, 250, Main, [WAIT($87), STR BCM87\11]	'Receive $87 (12) byte data packet on BCM Bus
    INTCON.7 = 1

But that will throw off your 4hz timing.

If possible, use the USART with HSERIN, and you won't need to disable anything.

[retepsnikrep]

I think i'll have to go back to something which leaves the timer running in the background i can poll the timer overflow flag and just count 4 ticks myself. Hmm?

Does your intcon just stop/start the timer?

I can't use hserin as chip is 12F683

[Darrel Taylor]

Polling the timer won't help, since it's the time it takes to execute the SERIN2 statement that causes the delay in responding to and reloading the timer. It can't do anything else until that statement is finished, and with a WAIT() in there, who knows how long it will take.

And INTCON.7 is the GIE bit (Global Interrupt Enable).
Setting it to 0 disables ALL interrupts, but does not affect the timer other than delaying the Interrupt Service Routine (ISR), which needs to reload the time to keep it accurate.

Depending on what your 4hz interrupt is doing, ... you may not need to worry about it interrupting the SERIN2. If the ISR is fast enough, it won't cause a problem.