Process control PI sketch

P

def scope():
  pv = [0]
  def actuate(x):
         pv[0] += x
  def read():
         return pv[0]
  return actuate, read


def scope_u():
  i = [0]
  kp = 0.01
  ki = 0.02
  def u(pv, sp):
         e = sp - pv
         print 'pv=', pv, 'sp=', sp, 'i(e)=', i[0]
         i[0] += e
         return kp * e + ki*i[0]
  return u

def run():
  import time
  u = scope_u()
  actuate, read = scope()
  while True:
    actuate(u(read(), 3.14))
    time.sleep(0.5)