- Controller: read back power

- Mass: do power quantization
- pid has extra optional dErr parameter

git-svn-id: http://moon:8086/svn/projects/HendiControl@224 fda53097-d464-4ada-af97-ba876c37ca34

Control/brewpi/pid.py

@@ -23,7 +23,7 @@ class Pid():
         p = dict(kp=kp, ki=ki, kd=kd, rho=rho)
         return p
 
-    def process(self, dt, params, err):
+    def process(self, dt, params, err, derr=None):
         kp = params['kp']
         ki = params['ki']
         kd = params['kd']
@@ -31,7 +31,11 @@ class Pid():
 
         err_aw = err + self.diff_aw
         yi = rho*self.yi + err_aw
-        yd = err - self.xd
+
+        if derr:
+            yd = derr
+        else:
+            yd = err - self.xd
 
         _yp = kp * err
         _yi = ki*dt * yi