pwm_cmd.m

Matlab学习课件

function pwm_cmd
% Produces the command for use by the PWM generator

pwm_glbl 	% Global definitions

% The 'next-state'is maintained as a separate variable so that the
% initialization canbe handled correctly and so a test can be
% constructed to tell whether the entry function of a state
% should be run. The next-state variable must be static so it
% remembered across function invocations. The 'global' designation
% is the only way Matlab has of making a variable static.
% The default value of the next-state variable is -1, indicating
% that no state change has taken place.

global Spwm_cmd_next % Next state for this task (other local statics
	% can be listed here.
	% These aren't really global,  but do have to be 'static'
	% Matlab doesn't have a 'static' declaration so this will have to do!

if Spwm_cmd == 0
	% Initialization section - occurs once only
	Spwm_cmd = 1;	% Make sure this section is not executed again!
	Spwm_cmd_next = 1;	% First state.
		%The default is -1 which indicates stay in same state
	return;
end

% This task runs at specific times. If current time has not reached
% the scheduled run time, just return.
if tstep < Tpwm_cmd
	return;
end

Tpwm_cmd = Tpwm_cmd + Tcmd_delt;	% Time for next run -- in this case
	% the task runs at regular intervals, but that needn't
	% be true all the time.

if Spwm_cmd_next ~= -1
	% There has been a state change (including self-transition)
	[i_audit,trans_trail] = audit(1,Spwm_cmd,Spwm_cmd_next,...
		tstep,trans_trail,i_audit);
		% Record this transition
	Spwm_cmd = Spwm_cmd_next;
	run_entry = 1;
	Spwm_cmd_next = -1;	% Default - stay in same state
else
	run_entry = 0;
end

% This task has only one state -- it produces a command duty cycle as
% a function of time.

% Run the code associated with the current state
if Spwm_cmd == 1
	% Entry section
	% No entry section for pwm_cmd

	% Action section
	duty_cycle = 0.5 * sin(tstep * 2 * pi / cmd_period) + 0.5; 
		% Result is in range 0->1	
	%Test/exit section 
	% This task has only one state - no transitions!

else	% Check for a state variable value that doesn't
	% to a defined state.
	error('Task: pwm_cmd -- unknown state encountered');
end