Update files related calibration.

Author: embedded-kiddie

README.md

@@ -124,12 +124,28 @@ MLX90640.ino
     - `USE_PREFERENCES`
   - Step5: Resolution
 
-### Dual-Core Timing Diagram
+### Dual-Core / Multitask Timing Diagram
 ![Timing Diagram](images/TimingDiagram.png)
 
+## Touch Screen Calibration
+
+The “Calibration Screen” will appear when you run the sketch for the first time after compile & uploading, 
+or when you select to run calibration from the menu.
+
+<details>
+<summary>Calibration Screen</summary>
+
+![Calibration Screen](images/TouchCalibration.jpg)
+</details>
+
+If `USE_PREFERENCES` is set to `true`, you can save the calibration results to flash, but when it's set to `false`, 
+you need to open the serial monitor before running the calibration and embed the displayed data into `touch.hpp` 
+after calibration is completed.
+
 ## Related Project
 - [MLX90640Viewer](https://github.com/embedded-kiddie/MLX90640Viewer)  
-    The MLX90640Viewer is a tool that applies heatmaps and visualizes the output of the Melexis MLX90640 32x24 IR array, which is stored as continuous raw data in a file.
+    The MLX90640Viewer is a tool that applies heatmaps and visualizes the output of the Melexis MLX90640 32x24 IR array, 
+    which is stored as continuous raw data in a file.
 
 - [MLX90640 for Arduino UNO R4][23]
 

images/TouchCalibration.jpg

@@ -248,7 +248,7 @@ void touch_calibrate(TouchConfig_t *config) {
   extern TFT_eSPI tft;
   sp.calibrateTouch(config->cal, &tft, TFT_WHITE, TFT_BLACK);
 
-  printf("\n// XPT2046\n");
+  printf("\n// XPT2046_Touchscreen\n");
   printf(".cal = { ");
   for (int i = 0; i < 5; ++i) {
     printf("%d", config->cal[i]);

touch.hpp

@@ -1495,6 +1495,9 @@ static void onCalibrationAdjust(const Widget_t *widget, const Touch_t &touch) {
 static void onCalibrationSave(const Widget_t *widget, const Touch_t &touch) {
   DBG_FUNC(printf("%s\n", __func__));
 
+  // Only when using flash is true
+  enable_save &= USE_PREFERENCES;
+
   if (touch.event == EVENT_INIT) {
     DrawButton(widget, enable_save);
   }