add two point calibration (no UI yet)

Core/Src/app_temp.c

@@ -11,136 +11,162 @@
 #include "adc.h"
 #include "snprintf.h"
 #include "app_safety.h"
+#include "eeprom_emul_types.h"
+#include "eeprom_emul.h"
+#include "ee_addresses.h"
+#include "transmute.h"
 
 /* DMA dest */
 static volatile uint16_t adc_values[4];
 
 const float V_REFINT = 1.23f;
 
-#define AVERAGEBUF_DEPTH 8
+#define AVERAGEBUF_DEPTH 16
-#define OVENTEMP_HISTORY_DEPTH 5
+#define OVENTEMP_HISTORY_DEPTH 20
 
 static struct App {
   float oven_temp;
   float soc_temp;
   float v_sensor;
+  float cal_a;
+  float cal_b;
   uint16_t adc_averagebuf[AVERAGEBUF_DEPTH * 4];
   uint8_t averagebuf_ptr;
   float adc_averages[4];
   float oventemp_history[OVENTEMP_HISTORY_DEPTH];
   uint8_t oventemp_history_ptr;
-} s_analog = {};
+} s_analog = {
+        .cal_a = 1.0f,
+        .cal_b = 0.0f,
+};
 
 #define TSENSE_LOOKUP_LEN 101
 #define TSENSE_T_STEP 5.0f
 #define TSENSE_T_MIN 0.0f
 #define TSENSE_T_MAX 500.0f
 static const float TSENSE_LOOKUP[TSENSE_LOOKUP_LEN] = {
-        0.092678405931418f,
+        0.0909090909090909f,
-        0.0943174479327356f,
+        0.0925200328471449f,
-        0.095948157844312f,
+        0.0941228958173389f,
-        0.0975706768542549f,
+        0.0957178169362106f,
-        0.0991848957506647f,
+        0.0973046872002769f,
-        0.100791037522732f,
+        0.0988837241910161f,
-        0.102388993070241f,
+        0.100454819038946f,
-        0.103978983136042f,
+        0.102018187184848f,
-        0.105560980458654f,
+        0.103573800259031f,
-        0.107135039851509f,
+        0.105121710606384f,
-        0.108701215616829f,
+        0.106661970090864f,
-        0.110259642413441f,
+        0.108194709632656f,
-        0.111810211533421f,
+        0.109719820815089f,
-        0.113353137226489f,
+        0.111237512887056f,
-        0.114888310929339f,
+        0.112747677594865f,
-        0.11641594480226f,
+        0.114250522193605f,
-        0.117936009906507f,
+        0.115746016789507f,
-        0.119448557132363f,
+        0.117234210034522f,
-        0.120953636903929f,
+        0.118715150141415f,
-        0.122451377845456f,
+        0.120188962295434f,
-        0.12394167187544f,
+        0.121655538774297f,
-        0.125424725109556f,
+        0.123115081061434f,
-        0.126900429638119f,
+        0.124567481621389f,
-        0.128368989630084f,
+        0.126012940077612f,
-        0.129830374697352f,
+        0.127451425220842f,
-        0.131284632150064f,
+        0.128882982328346f,
-        0.132731808872517f,
+        0.13030765627567f,
-        0.134172027901771f,
+        0.131725566931108f,
-        0.135605181883591f,
+        0.133136607355006f,
-        0.13703146935069f,
+        0.134540971782401f,
-        0.138450783142958f,
+        0.135938553479917f,
-        0.139863319976468f,
+        0.137329544944786f,
-        0.14126904821384f,
+        0.138713913835562f,
-        0.142668011892657f,
+        0.140091702340679f,
-        0.144060254660872f,
+        0.141462952280536f,
-        0.145445894373796f,
+        0.142827778585901f,
-        0.146824824486877f,
+        0.144186075171443f,
-        0.14819723645253f,
+        0.145538029496198f,
-        0.149563023938454f,
+        0.146883535696824f,
-        0.150922376699229f,
+        0.148222779606307f,
-        0.15227526202401f,
+        0.149555727912261f,
-        0.153621720954182f,
+        0.150882419971517f,
-        0.15496179417407f,
+        0.152202894803216f,
-        0.156295594725426f,
+        0.153517262745702f,
-        0.157623016940038f,
+        0.154825418625535f,
-        0.158944245649448f,
+        0.156127543558165f,
-        0.160259175412251f,
+        0.157423532604634f,
-        0.16156798947087f,
+        0.158713565356767f,
-        0.162870654195634f,
+        0.159997607673187f,
-        0.164167207880495f,
+        0.161275696311014f,
-        0.165457688491696f,
+        0.162547867717066f,
-        0.166742204592451f,
+        0.163814227951767f,
-        0.168020651444079f,
+        0.165074672799026f,
-        0.169293207677971f,
+        0.166329377427284f,
-        0.170559768793747f,
+        0.167578237864685f,
-        0.171820511933356f,
+        0.168821427850084f,
-        0.173075402684405f,
+        0.170058912538152f,
-        0.174324476817747f,
+        0.171290726295724f,
-        0.175567769803026f,
+        0.172516903204089f,
-        0.176805386030345f,
+        0.17373754533289f,
-        0.178037221732226f,
+        0.174952549458501f,
-        0.179263449725904f,
+        0.176162085166716f,
-        0.180483966491086f,
+        0.177366049485545f,
-        0.181698943447122f,
+        0.178564610657697f,
-        0.182908345518766f,
+        0.179757733244091f,
-        0.184112206156428f,
+        0.180945449410727f,
-        0.185310558533273f,
+        0.182127791060477f,
-        0.186503503145257f,
+        0.183304856534839f,
-        0.187690937227925f,
+        0.184476543628915f,
-        0.188873028139146f,
+        0.185643016681207f,
-        0.190049673368296f,
+        0.186804173743842f,
-        0.191221038959601f,
+        0.18796017789194f,
-        0.192387089280576f,
+        0.18911099318983f,
-        0.193547855644572f,
+        0.190256649774341f,
-        0.194703369109397f,
+        0.191397177539504f,
-        0.195853726532112f,
+        0.192532671339319f,
-        0.196998826174689f,
+        0.193663030006298f,
-        0.19813883026229f,
+        0.194788412940845f,
-        0.199273637315452f,
+        0.195908719236171f,
-        0.200403408323351f,
+        0.197024107102852f,
-        0.201528107189346f,
+        0.198134540194308f,
-        0.20264776325594f,
+        0.19924004677399f,
-        0.203762405629782f,
+        0.200340654881021f,
-        0.204872127762998f,
+        0.201436456102762f,
-        0.205976828960191f,
+        0.202527350321362f,
-        0.207076666615101f,
+        0.203613492284647f,
-        0.208171540293999f,
+        0.204694782137667f,
-        0.209261606226334f,
+        0.205771373506423f,
-        0.210346827933364f,
+        0.206843229708988f,
-        0.211427232937629f,
+        0.20791037727704f,
-        0.212502848543705f,
+        0.208972842534733f,
-        0.213573765013592f,
+        0.210030714005839f,
-        0.214639882704581f,
+        0.211083892628833f,
-        0.215701354457324f,
+        0.212132528763072f,
-        0.216758080892489f,
+        0.213176523610881f,
-        0.217810213752734f,
+        0.214216026472748f,
-        0.218857716249547f,
+        0.215251000398025f,
-        0.219900614222686f,
+        0.216281470315524f,
-        0.220938933310224f,
+        0.21730746096184f,
-        0.221972760781578f,
+        0.218329057984116f,
-        0.223001998051553f,
+        0.219346163379138f,
 };
 
 void app_analog_init()
 {
+    // read calibration constants
+    uint32_t c = 0;
+    if (EE_OK == EE_ReadVariable32bits(EE_ADDR_CAL_A, &c)) {
+        s_analog.cal_a = ((x32_t) { .u = c }).f;
+        PRINTF("ADC calib a read from EE: %f\r\n", s_analog.cal_a);
+    }
+    if (EE_OK == EE_ReadVariable32bits(EE_ADDR_CAL_B, &c)) {
+        s_analog.cal_b = ((x32_t) { .u = c }).f;
+        PRINTF("ADC calib b read from EE: %f\r\n", s_analog.cal_b);
+    }
+
+    if (s_analog.cal_a == 0.0f || s_analog.cal_b == 0.0f) {
+        PRINTF("ADC invalid calib, reset\r\n");
+        s_analog.cal_a = 1.0f;
+        s_analog.cal_b = 0.0f;
+    }
+
     LL_ADC_Enable(ADC_TEMP);
 
     LL_ADC_StartCalibration(ADC_TEMP);
@@ -203,6 +229,13 @@ void app_temp_sample()
     s_analog.adc_averages[2] = (float) sums[2] / count;
     s_analog.adc_averages[3] = (float) sums[3] / count;
 
+    PRINTF("%f\t%f\t%f\t%f\r\n",
+           s_analog.adc_averages[0],
+                   s_analog.adc_averages[1],
+                   s_analog.adc_averages[2],
+                   s_analog.adc_averages[3]
+           );
+
     /* r_pt100, r_ref, internal_temp, v_ref_int */
     float refint = s_analog.adc_averages[3];
     float scale = V_REFINT / refint;
@@ -217,7 +250,11 @@ void app_temp_sample()
 
     // using a voltage divider, so assuming the reference resistor is measured well,
     // we can just use the ratio and the exact voltage value is not important.
-    float actual_temp = val_to_c(s_analog.adc_averages[0] / s_analog.adc_averages[1]);
+
+    float x = s_analog.adc_averages[0] / s_analog.adc_averages[1];
+    float y = s_analog.cal_a * x + s_analog.cal_b;
+    float actual_temp = val_to_c(y);
+    PRINTF("Compensated x %f -> y %f, temp %f C\r\n", x, y, actual_temp);
 
     s_analog.oventemp_history[s_analog.oventemp_history_ptr] = actual_temp;
     s_analog.oventemp_history_ptr = (s_analog.oventemp_history_ptr + 1) % OVENTEMP_HISTORY_DEPTH;

Core/Src/ee_addresses.h

@@ -0,0 +1,13 @@
+//
+// Created by MightyPork on 2023/04/09.
+//
+
+#ifndef TOASTER_OVEN_BLUEPILL_EE_ADDRESSES_H
+#define TOASTER_OVEN_BLUEPILL_EE_ADDRESSES_H
+
+enum EEAddresses {
+    EE_ADDR_CAL_A = 1,
+    EE_ADDR_CAL_B = 2,
+};
+
+#endif //TOASTER_OVEN_BLUEPILL_EE_ADDRESSES_H

Core/Src/transmute.h

@@ -0,0 +1,15 @@
+//
+// Created by MightyPork on 2023/04/09.
+//
+
+#ifndef TOASTER_OVEN_BLUEPILL_TRANSMUTE_H
+#define TOASTER_OVEN_BLUEPILL_TRANSMUTE_H
+
+#include <stdint.h>
+
+typedef union x32 {
+    uint32_t u;
+    float f;
+} x32_t;
+
+#endif //TOASTER_OVEN_BLUEPILL_TRANSMUTE_H