function [t,y,u]=escada(Vo,to,dt,n,placa)
%   [t,y,u] = escada(Vo,to,dt,n,placa)
%

if nargin<5,
    placa = 'Dev1';
end
if nargin<4,
    n = 1024;
end
if nargin<3,
    dt = 0;
end
if nargin<2,
    to = 1;
end
if nargin<1,
    Vo = 1.0;
end

d = daq.getDevices
s = daq.createSession('ni')
s.addAnalogOutputChannel(placa,'ao0','Voltage')
s.addAnalogInputChannel(placa,'ai0','Voltage')

t = [];
y = [];
u = [];
outputSingleScan(s,0);
y(1)=inputSingleScan(s);
tic
fprintf('Início\n\n');
t(1) = toc;
tt = t(1);
c=1;
u(1)=0;
for i = 2:n,
    if t(i-1)-tt<c*to,
        u(i)=u(i-1);
    else
        u(i)=c*Vo;
        c = c+1;
    end
    outputSingleScan(s,u(i));
    y(i)=inputSingleScan(s);
    t(i)=toc;
    fprintf('%d:  t = %4.2f s     v = %4.2f V\n',i,t(i),y(i));
%     [y(i),t(i)]=inputSingleScan(s);
    if dt>= 1.0,
        pause(dt);
    end
end
t=t-tt;
fprintf('Total elapsed time = %3.2f s\n',toc)
fprintf('Fim!')
outputSingleScan(s,0);

daq.reset
beep

return