This solution uses the square() funciton which converts a sin wave into a square wave with normalized values between [-1:1]. All you have to do is create a sin wave that fits your description, convert it to square wave, and then vertically scale it.
% Set params
width = 1.0; % Width of each step
height = 1.0; % Height of step (max - min)
base = 0.0; % min value
start = -3; % starting x value
stop = 3; % ending x value
res = 0.001; % resolution
horzShift = .5; % horizontally shift (negative = leftward)
% Compute square wave
x = start : res : stop;
y = (square(sin((x+horzShift)/width*pi))+1)/2*height + base;
% figure
plot(x,y, 'k-', 'linewidth', 3)
ylim([base - 1, base+height+1])
