Re: sequencer & button click

[Benjamin Franksen <benjamin.franksen@helmholtz-berlin.de>]

On Friday, July 20, 2012, Martin Konrad wrote:
> what's the recommended way to switch from one sequencer state to another
> if a button is clicked on the OPI? What type of record do you use for
> this? What does the "when" statement look like?

One possibility is to use an mbbo record, where the mbbo choices correspond 
to the states in the SNL program.

The code would be something like 

#define STATE_X 0
#define STATE_Y 1

int state_change;
assign state_change to ...;
monitor state_change;

ss ... {
	...
	state X {
		when (state_change == STATE_Y) {} state Y
	}
	state Y {
		when (state_change == STATE_X) {} state X
	}
}

However, what I usually do is to use bo records for all user commands. The 
button sets the command record to 1, the state machine if in state idle) 
changes state, performs the command, then resets the command record to zero, 
indicating completion, then finally returns to the idle state. You can use 
an mbboDirect and/or a calc record to gather all the command records into a 
single value, for instance to determine whether any command is currently 
being performed (so the state machine is busy) or check against a mask or 
whatever.

> P.S.: When coupling a button with some piece of hardware I usually use
> some sort of record that is scanned if the button is clicked. This
> results in a message to my device. This obviously does not work with the
> sequencer because the value of the record does not change and thus a
> monitor would not fire...

This is not correct, strictly speaking: it depends on the record type and 
the record's configuration. The ai/ao/[mb]bi/[mb]bo records send monitors on 
each process (even if the value does not change) if you set MDEL to -1. 
Stringin/out always send monitors.

Cheers
Ben

Attachment: signature.asc
Description: This is a digitally signed message part.