Added support for a heated bed thermistor that can be different from the hot-end thermistor

Tonokip_Firmware/BedThermistorTable.h

@@ -0,0 +1,33 @@
+// Thermistor lookup table for RepRap Temperature Sensor Boards (http://make.rrrf.org/ts)
+// Made with createTemperatureLookup.py (http://svn.reprap.org/trunk/reprap/firmware/Arduino/utilities/createTemperatureLookup.py)
+// ./createTemperatureLookup.py --r0=10000 --t0=25 --r1=0 --r2=4700 --beta=3977 --max-adc=1023
+// r0: 10000
+// t0: 25
+// r1: 0
+// r2: 4700
+// beta: 3977
+// max adc: 1023
+#define NUMTEMPS 20
+short bedtemptable[NUMTEMPS][2] = {
+   {1, 430},
+   {54, 137},
+   {107, 107},
+   {160, 91},
+   {213, 80},
+   {266, 71},
+   {319, 64},
+   {372, 57},
+   {425, 51},
+   {478, 46},
+   {531, 41},
+   {584, 35},
+   {637, 30},
+   {690, 25},
+   {743, 20},
+   {796, 14},
+   {849, 7},
+   {902, 0},
+   {955, -11},
+   {1008, -35}
+};
+

Tonokip_Firmware/Tonokip_Firmware.pde

@@ -4,6 +4,7 @@
 #include "configuration.h"
 #include "pins.h"
 #include "ThermistorTable.h"
+#include "BedThermistorTable.h"
 #ifdef SDSUPPORT
 #include "SdFat.h"
 #endif
@@ -504,13 +505,13 @@ inline void process_commands()
         if (code_seen('S')) target_raw = temp2analog(code_value());
         break;
       case 140: // M140 set bed temp
-        if (code_seen('S')) target_bed_raw = temp2analog(code_value());
+        if (code_seen('S')) target_bed_raw = temp2analogBed(code_value());
         break;
       case 105: // M105
         Serial.print("T:");
         Serial.println( analog2temp(analogRead(TEMP_0_PIN)) ); 
         Serial.print("Bed:");
-        Serial.println( analog2temp(analogRead(TEMP_1_PIN)) ); 
+        Serial.println( analog2tempBed(analogRead(TEMP_1_PIN)) ); 
         if(!code_seen('N')) {
             return;  // If M105 is sent from generated gcode, then it needs a response.
         }
@@ -776,7 +777,7 @@ inline void manage_heater()
     }
 }
 
-// Takes temperature value as input and returns corresponding analog value from RepRap thermistor temp table.
+// Takes hot end temperature value as input and returns corresponding analog value from RepRap thermistor temp table.
 // This is needed because PID in hydra firmware hovers around a given analog value, not a temp value.
 // This function is derived from inversing the logic from a portion of getTemperature() in FiveD RepRap firmware.
 float temp2analog(int celsius) {
@@ -806,7 +807,38 @@ float temp2analog(int celsius) {
   }
 }
 
+// Takes bed temperature value as input and returns corresponding analog value from RepRap thermistor temp table.
+// This is needed because PID in hydra firmware hovers around a given analog value, not a temp value.
+// This function is derived from inversing the logic from a portion of getTemperature() in FiveD RepRap firmware.
+float temp2analogBed(int celsius) {
+  if(USE_THERMISTOR) {
+    int raw = 0;
+    byte i;
+    
+    for (i=1; i<NUMTEMPS; i++)
+    {
+      if (bedtemptable[i][1] < celsius)
+      {
+        raw = bedtemptable[i-1][0] + 
+          (celsius - bedtemptable[i-1][1]) * 
+          (bedtemptable[i][0] - bedtemptable[i-1][0]) /
+          (bedtemptable[i][1] - bedtemptable[i-1][1]);
+      
+        break;
+      }
+    }
+
+    // Overflow: Set to last value in the table
+    if (i == NUMTEMPS) raw = bedtemptable[i-1][0];
+
+    return 1023 - raw;
+  } else {
+    return celsius * (1024.0/(5.0*100.0));
+  }
+}
+
 // Derived from RepRap FiveD extruder::getTemperature()
+// For hot end thermistor.
 float analog2temp(int raw) {
   if(USE_THERMISTOR) {
     int celsius = 0;
@@ -835,6 +867,36 @@ float analog2temp(int raw) {
   }
 }
 
+// Derived from RepRap FiveD extruder::getTemperature()
+// For bed thermistor.
+float analog2tempBed(int raw) {
+  if(USE_THERMISTOR) {
+    int celsius = 0;
+    byte i;
+
+    for (i=1; i<NUMTEMPS; i++)
+    {
+      if (bedtemptable[i][0] > raw)
+      {
+        celsius  = bedtemptable[i-1][1] + 
+          (raw - bedtemptable[i-1][0]) * 
+          (bedtemptable[i][1] - bedtemptable[i-1][1]) /
+          (bedtemptable[i][0] - bedtemptable[i-1][0]);
+
+        break;
+      }
+    }
+
+    // Overflow: Set to last value in the table
+    if (i == NUMTEMPS) celsius = bedtemptable[i-1][1];
+
+    return celsius;
+    
+  } else {
+    return raw * ((5.0*100.0)/1024.0);
+  }
+}
+
 inline void kill(byte debug)
 {
   if(HEATER_0_PIN > -1) digitalWrite(HEATER_0_PIN,LOW);