Rough tip resistance progress

source/Core/BSP/BSP_Power.h

@@ -16,6 +16,13 @@ extern "C" {
 // Can be used to check any details for the power system
 void power_check();
 
+// Returns the tip resistance in x10 ohms, so 7.5 = 75; 14=140 etc
+uint8_t getTipResitanceX10();
+
+// Called when device is idle to allow measuring tip resistance
+void startMeasureTipResistance();
+void FinishMeasureTipResistance();
+
 #ifdef __cplusplus
 }
 #endif

source/Core/BSP/Magic/BSP.cpp

@@ -223,3 +223,47 @@ bool isTipDisconnected() {
 void setStatusLED(const enum StatusLED state) {
   // Dont have one
 }
+
+uint8_t  lastTipResistance = 75; // default safe
+uint32_t lastTipReadinguV  = 0;
+uint8_t  getTipResitanceX10() {
+  // Return tip resistance in x10 ohms
+  // We can measure this using the op-amp
+  return lastTipResistance;
+}
+void startMeasureTipResistance() {
+
+  if (isTipDisconnected()) {
+    return;
+  }
+
+  // We want to calculate lastTipResistance
+  // If tip is connected, and the tip is cold and the tip is not being heated
+  // We can use the GPIO to inject a small current into the tip and measure this
+  // The gpio is 5.1k -> diode -> tip -> gnd
+  // Which is around 0.65mA this will induce:
+  // 6 ohm tip -> 3.9mV (Real world ~= 3320)
+  // 8 ohm tip -> 5.2mV (Real world ~= 4500)
+  // Which is definitely measureable
+  // Taking shortcuts here as we know we only really have to pick apart 6 and 8 ohm tips
+  // These are reported as 60 and 75 respectively
+  lastTipReadinguV = TipThermoModel::convertTipRawADCTouV(getTipRawTemp(0));
+  gpio_write(TIP_RESISTANCE_SENSE, 1);
+  // Wait for next ADC measurement
+}
+
+void FinishMeasureTipResistance() {
+  gpio_write(TIP_RESISTANCE_SENSE, 0);
+  if (isTipDisconnected()) {
+    return;
+  }
+  // read the tip uV with the current source on
+  uint32_t newReading = (TipThermoModel::convertTipRawADCTouV(getTipRawTemp(0)));
+  if (newReading < lastTipReadinguV) {
+    return;
+  }
+  // newReading -= lastTipReadinguV;
+  MSG("Tip Delta %lu, %lu %lu \r\n", newReading - lastTipReadinguV, newReading, lastTipReadinguV);
+  newReading -= lastTipReadinguV;
+  lastTipReadinguV = newReading;
+}

source/Core/BSP/Magic/IRQ.cpp

@@ -23,6 +23,7 @@ history<uint16_t, ADC_Filter_Smooth> ADC_Vin;
 history<uint16_t, ADC_Filter_Smooth> ADC_Temp;
 history<uint16_t, ADC_Filter_Smooth> ADC_Tip;
 
+
 void adc_fifo_irq(void) {
   if (ADC_GetIntStatus(ADC_INT_FIFO_READY) == SET) {
     bool wakePID = false;

source/Core/BSP/Magic/Setup.cpp

@@ -29,8 +29,9 @@ void hardware_init() {
   gpio_set_mode(TMP36_INPUT_Pin, GPIO_INPUT_MODE);
   gpio_set_mode(TIP_TEMP_Pin, GPIO_INPUT_MODE);
   gpio_set_mode(VIN_Pin, GPIO_INPUT_MODE);
-  gpio_set_mode(TIP_RESISTANCE_SENSE, GPIO_INPUT_MODE);
+  gpio_set_mode(TIP_RESISTANCE_SENSE, GPIO_OUTPUT_PP_MODE);
-
+  gpio_write(TIP_RESISTANCE_SENSE, 0);
+  MSG("Magic Starting\r\n");
   setup_timer_scheduler();
   setup_adc();
   setup_pwm();

source/Core/BSP/Magic/configuration.h

@@ -116,17 +116,17 @@
 #ifdef MODEL_Magic
 #define ADC_VDD_MV             3200                      // ADC max reading millivolts
 #define SOLDERING_TEMP         320                       // Default soldering temp is 320.0 °C
-#define VOLTAGE_DIV            600                       // 290 - Default divider from schematic
+#define VOLTAGE_DIV            600                       // 600 - Default divider from schematic
-#define CALIBRATION_OFFSET     900                       // 900 - Default adc offset in uV
+#define CALIBRATION_OFFSET     800                       // 900 - Default adc offset in uV
 #define MIN_CALIBRATION_OFFSET 100                       // Min value for calibration
-#define PID_POWER_LIMIT        70                        // Sets the max pwm power limit
+#define PID_POWER_LIMIT        220                       // Sets the max pwm power limit
 #define POWER_LIMIT            0                         // 0 watts default limit
-#define MAX_POWER_LIMIT        70                        //
+#define MAX_POWER_LIMIT        220                       //
 #define POWER_LIMIT_STEPS      5                         //
 #define OP_AMP_GAIN_STAGE      OP_AMP_GAIN_STAGE_PINECIL // Uses TS100 resistors
 #define TEMP_uV_LOOKUP_HAKKO                             // Use Hakko lookup table
 #define USB_PD_VMAX            20                        // Maximum voltage for PD to negotiate
-#define PID_TIM_HZ             (8)                       // Tick rate of the PID loop
+#define PID_TIM_HZ             (10)                      // Tick rate of the PID loop
 #define MAX_TEMP_C             450                       // Max soldering temp selectable °C
 #define MAX_TEMP_F             850                       // Max soldering temp selectable °F
 #define MIN_TEMP_C             10                        // Min soldering temp selectable °C

source/Core/Drivers/USBPD.cpp

@@ -13,9 +13,6 @@
 #ifndef USB_PD_VMAX
 #error Max PD Voltage must be defined
 #endif
-#ifndef TIP_RESISTANCE
-#error Tip resistance must be defined
-#endif
 
 void ms_delay(uint32_t delayms) {
   // Convert ms -> ticks
@@ -98,10 +95,10 @@ bool pdbs_dpm_evaluate_capability(const pd_msg *capabilities, pd_msg *request) {
 #ifdef MODEL_HAS_DCDC
         // If this device has step down DC/DC inductor to smooth out current spikes
         // We can instead ignore resistance and go for max voltage we can accept
-        min_resistance_ohmsx10 = TIP_RESISTANCE;
+        min_resistance_ohmsx10 = getTipResitanceX10();
 #endif
         // Fudge of 0.5 ohms to round up a little to account for other losses
-        if (min_resistance_ohmsx10 <= (TIP_RESISTANCE + 5)) {
+        if (min_resistance_ohmsx10 <= (getTipResitanceX10() + 5)) {
           // This is a valid power source we can select as
           if ((voltage_mv > bestIndexVoltage) || bestIndex == 0xFF) {
             // Higher voltage and valid, select this instead
@@ -124,7 +121,7 @@ bool pdbs_dpm_evaluate_capability(const pd_msg *capabilities, pd_msg *request) {
       // Using the current and tip resistance, calculate the ideal max voltage
       // if this is range, then we will work with this voltage
       // if this is not in range; then max_voltage can be safely selected
-      int ideal_voltage_mv = (TIP_RESISTANCE * max_current);
+      int ideal_voltage_mv = (getTipResitanceX10() * max_current);
       if (ideal_voltage_mv > max_voltage) {
         ideal_voltage_mv = max_voltage; // constrain
       }
@@ -186,7 +183,7 @@ void pdbs_dpm_get_sink_capability(pd_msg *cap, const bool isPD3) {
   // if (requested_voltage_mv != 5000) {
   //   voltage = requested_voltage_mv;
   // }
-  // uint16_t current = (voltage) / TIP_RESISTANCE; // In centi-amps
+  // uint16_t current = (voltage) / getTipResitanceX10(); // In centi-amps
 
   // /* Add a PDO for the desired power. */
   // cap->obj[numobj++] = PD_PDO_TYPE_FIXED | PD_PDO_SNK_FIXED_VOLTAGE_SET(PD_MV2PDV(voltage)) | PD_PDO_SNK_FIXED_CURRENT_SET(current);

source/Core/Src/power.cpp

@@ -49,7 +49,7 @@ uint32_t availableW10(uint8_t sample) {
   //				R = R*10
   // P therefore is in V^2*100/R*10 = W*10.
   uint32_t v                 = getInputVoltageX10(getSettingValue(SettingsOptions::VoltageDiv), sample); // 100 = 10v
-  uint32_t availableWattsX10 = (v * v) / TIP_RESISTANCE;
+  uint32_t availableWattsX10 = (v * v) / getTipResitanceX10();
   // However, 100% duty cycle is not possible as there is a dead time while the ADC takes a reading
   // Therefore need to scale available milliwats by this
 

source/Core/Threads/PIDThread.cpp

@@ -46,11 +46,14 @@ void startPIDTask(void const *argument __unused) {
     getInputVoltageX10(getSettingValue(SettingsOptions::VoltageDiv), 1);
   }
   int32_t x10WattsOut            = 0;
-
+  bool    measuringTipResistance = false;
   for (;;) {
     x10WattsOut = 0;
     // This is a call to block this thread until the ADC does its samples
     if (ulTaskNotifyTake(pdTRUE, 2000)) {
+      if (measuringTipResistance) {
+        FinishMeasureTipResistance();
+      }
       // Do the reading here to keep the temp calculations churning along
       uint32_t currentTipTempInC = TipThermoModel::getTipInC(true);
       PIDTempTarget              = currentTempTargetDegC;
@@ -72,6 +75,11 @@ void startPIDTask(void const *argument __unused) {
         detectThermalRunaway(currentTipTempInC, 0);
       }
       setOutputx10WattsViaFilters(x10WattsOut);
+      // If the output is off, take tip measurement reading
+      if (x10WattsOut == 0 && PIDTempTarget == 0) {
+        startMeasureTipResistance();
+        measuringTipResistance = true;
+      }
     } else {
       // ADC interrupt timeout
       setTipPWM(0, false);