Configtool: thermistor table entries are now distributed by ADC.

Previously they were evenly spaced across the temperature range,
now they're evenly distributed across the ADC range ... which
is not entirely the same.

This is related to issue #176.

configtool/thermistor.py

@@ -37,9 +37,16 @@ class SHThermistor:
     except:
       return None, None
 
+  def temp(self, adc):
+    r = self.adcInv(adc)
+    t = (1.0 / (self.A + self.B * log(r) + self.C * (log(r) ** 3))) - 273.15;
+    return t
+
   def adc(self, r):
     return 1023.0 * r / (r + self.rp)
 
+  def adcInv(self, adc):
+    return (self.rp * adc)/(1023.0 - adc)
 
 class BetaThermistor:
   def __init__(self, r0, t0, beta, r1, r2, vadc):
@@ -86,3 +93,6 @@ class BetaThermistor:
       return round(v / self.vadc * 1024), r
     except:
       return None, None
+
+  def adcInv(self, adc):
+    return (adc * self.vadc)/1024.0

configtool/thermistortablefile.py

@@ -65,9 +65,6 @@ def generateTempTables(sensors, settings):
     ofp.close();
     return True
 
-  step = int((300.0 / (N-1) + 1))
-  idx = range(step*(N-1), -step, -step)
-
   ofp.output("const uint16_t PROGMEM temptable[NUMTABLES][NUMTEMPS][2] = {")
 
   tcount = 0
@@ -75,9 +72,9 @@ def generateTempTables(sensors, settings):
     tcount += 1
     finalTable = tcount == len(tl)
     if len(tn[0]) == 4:
-      BetaTable(ofp, tn[0], tn[1], idx, settings, finalTable)
+      BetaTable(ofp, tn[0], tn[1], settings, finalTable)
     elif len(tn[0]) == 7:
-      SteinhartHartTable(ofp, tn[0], tn[1], idx, settings, finalTable)
+      SteinhartHartTable(ofp, tn[0], tn[1], settings, finalTable)
     else:
       pass
 
@@ -85,7 +82,7 @@ def generateTempTables(sensors, settings):
   ofp.close()
   return True
 
-def BetaTable(ofp, params, names, idx, settings, finalTable):
+def BetaTable(ofp, params, names, settings, finalTable):
   r0 = params[0]
   beta = params[1]
   r2 = params[2]
@@ -100,20 +97,31 @@ def BetaTable(ofp, params, names, idx, settings, finalTable):
   thrm = BetaThermistor(int(r0), int(settings.t0), int(beta), int(settings.r1),
                         int(r2), vadc)
 
-  for t in idx:
-    a, r = thrm.setting(t)
-    if a is None:
-      ofp.output("// ERROR CALCULATING THERMISTOR VALUES AT TEMPERATURE %d" % t)
+  hiadc = thrm.setting(0)[0]
+  N = int(settings.numTemps)
+  step = int(hiadc / (N - 1))
+  idx = range(1, int(hiadc), step)
+
+  while len(idx) > N:
+    del idx[0]
+
+  for i in range(1, int(hiadc), step):
+    t = int(thrm.temp(i))
+    if t is None:
+      ofp.output("// ERROR CALCULATING THERMISTOR VALUES AT ADC %d" % i)
       continue
 
-    vTherm = a * vadc / 1024
+    v = thrm.adcInv(i)
+    r = thrm.resistance(t)
+
+    vTherm = i * vadc / 1024
     ptherm = vTherm * vTherm / r
-    if t <= 0:
+    if i + step >= int(hiadc):
       c = " "
     else:
       c = ","
     ostr = ("    {%4s, %5s}%s // %4d C, %6.0f ohms, %0.3f V,"
-            " %0.2f mW") % (int(round(a)), t*4, c, t, r,
+            " %0.2f mW") % (i, t * 4, c, t, int(round(r)),
             vTherm, ptherm * 1000)
     ofp.output(ostr)
 
@@ -122,7 +130,7 @@ def BetaTable(ofp, params, names, idx, settings, finalTable):
   else:
     ofp.output("  },")
 
-def SteinhartHartTable(ofp, params, names, idx, settings, finalTable):
+def SteinhartHartTable(ofp, params, names, settings, finalTable):
   ofp.output(("  // %s temp table using Steinhart-Hart algorithm with "
               "parameters:") % (", ".join(names)))
   ofp.output(("  // Rp = %s, T0 = %s, R0 = %s, T1 = %s, R1 = %s, "
@@ -135,18 +143,28 @@ def SteinhartHartTable(ofp, params, names, idx, settings, finalTable):
                       float(params[3]), int(params[4]), float(params[5]),
                       int(params[6]))
 
-  for t in idx:
-    a, r = thrm.setting(t)
-    if a is None:
-      ofp.output("// ERROR CALCULATING THERMISTOR VALUES AT TEMPERATURE %d" % t)
+  hiadc = thrm.setting(0)[0]
+  N = int(settings.numTemps)
+  step = int(hiadc / (N - 1))
+  idx = range(1, int(hiadc), step)
+
+  while len(idx) > N:
+    del idx[0]
+
+  for i in range(1, int(hiadc), step):
+    t = int(thrm.temp(i))
+    if t is None:
+      ofp.output("// ERROR CALCULATING THERMISTOR VALUES AT ADC %d" % i)
       continue
 
-    if t <= 0:
+    r = int(thrm.adcInv(i))
+
+    if i + step >= int(hiadc):
       c = " "
     else:
       c = ","
-    ofp.output("    {%4d, %5d}%s // %4d C, %6.0f ohms, %7.2f adc" %
-               (int(round(a)), t*4, c, t, int(round(r)), a))
+    ofp.output("    {%4d, %5d}%s // %4d C, %6d ohms" %
+               (i, t * 4, c, t, int(round(r))))
 
   if finalTable:
     ofp.output("  }")