diff -r 000000000000 -r b74b0e4902c3 main/calibration.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/calibration.c	Sat Oct 20 13:23:15 2018 +0200
@@ -0,0 +1,142 @@
+/**
+ * @file calibration.c
+ * @brief TFT screen calibration.
+ */
+
+#include "config.h"
+
+
+static const char		*TAG = "calibration";
+
+
+extern uint16_t                 tp_xleft;
+extern uint16_t                 tp_xright;
+extern uint16_t                 tp_ytop;
+extern uint16_t                 tp_ybottom;
+
+
+// Distance of the testpoints from the corders.
+#define	CAL_DISTANCE		15
+
+
+int TS_set_calibration(int xleft, int xright, int ytop, int ybottom)
+{
+    if ((xleft > xright) || (ybottom > ytop)) {
+	ESP_LOGE(TAG, "Touch Calibration error X=%d..%d Y=%d..%d", xleft, xright, ybottom, ytop);
+	return 1;
+    }
+
+    tp_xleft = xleft;
+    tp_xright = xright;
+    tp_ytop = ytop;
+    tp_ybottom = ybottom;
+    ESP_LOGI(TAG, "Touch Calibration X=%d..%d Y=%d..%d", xleft, xright, ybottom, ytop);
+
+    return 0;
+}
+
+
+
+void Calibration_Init(void)
+{
+    _fg = TFT_ORANGE;
+    TFT_setFont(DEJAVU24_FONT, NULL);
+    TFT_print("Scherm calibratie", CENTER, 60);
+    TFT_setFont(DEJAVU18_FONT, NULL);
+    TFT_print("Druk op de oplichtende stippen", CENTER, 90);
+}
+
+
+
+/*
+ * Run in a blocking loop
+ */
+void Calibration_Loop(void)
+{
+    int		tx, ty, pass, cx[8], cy[8], xl = 0, xh = 0, yl = 0, yh = 0;
+    int		offset;
+
+    pass = 0;
+    ESP_LOGI(TAG, "Touchscreen calibration");
+
+    while (1) {
+	switch (pass) {
+	    case 0:
+	    case 4:	TFT_fillCircle(320 - CAL_DISTANCE, 240 - CAL_DISTANCE, 5, TFT_BLACK);
+			TFT_fillCircle(CAL_DISTANCE,  CAL_DISTANCE, 5, TFT_YELLOW);
+			xl = 2800;
+			xh = 3800;
+			yl = 2800;
+			yh = 3800;
+			break;
+	    case 1:
+	    case 5:	TFT_fillCircle(CAL_DISTANCE,  CAL_DISTANCE, 5, TFT_BLACK);
+			TFT_fillCircle(320 - CAL_DISTANCE, CAL_DISTANCE, 5, TFT_YELLOW);
+			xl = 2800;
+			xh = 3800;
+			yl = 100;
+			yh = 1000;
+			break;
+	    case 2:
+	    case 6:	TFT_fillCircle(320 - CAL_DISTANCE, CAL_DISTANCE, 5, TFT_BLACK);
+			TFT_fillCircle(CAL_DISTANCE, 240 - CAL_DISTANCE, 5, TFT_YELLOW);
+			xl = 100;
+			xh = 1000;
+			yl = 2800;
+			yh = 3800;
+			break;
+	    case 3:
+	    case 7:	TFT_fillCircle(CAL_DISTANCE, 240 - CAL_DISTANCE, 5, TFT_BLACK);
+			TFT_fillCircle(320 - CAL_DISTANCE, 240 - CAL_DISTANCE, 5, TFT_YELLOW);
+			xl = 100;
+			xh = 1000;
+			yl = 100;
+			yh = 1000;
+			break;
+	}
+	if (TFT_read_touch(&tx, &ty, 1)) {  // Raw read touch.
+	    printf(" Calibrarion loop %d %d %d\n", pass, tx, ty);
+	    if ((tx >= xl) && (tx <= xh) && (ty >= yl) && (ty <= yh)) {
+	    	cx[pass] = tx;
+	    	cy[pass] = ty;
+	    	pass++;
+	    	if (pass == 8) {
+		    break;
+	    	}
+	    } else {
+		SoundPlay(SOUND_Warn);
+	    }
+	    WaitTouchReleased();
+	}
+	vTaskDelay(100 / portTICK_PERIOD_MS);
+    }
+
+    TFT_fillScreen(TFT_BLACK);
+    TFT_setFont(DEJAVU18_FONT, NULL);
+    TFT_print("Scherm calibratie is klaar.", CENTER, 60);
+    /*
+     * Calculate the new calibration values.
+     * The testdots were 10 pixels of the corners, 
+     * so take that in account.
+     */
+    offset = (CAL_DISTANCE * 3800) / 240;
+    config.ts_xleft   = ((cx[2] + cx[3] + cx[6] + cx[7]) / 4) - offset;
+    config.ts_xright  = ((cx[0] + cx[1] + cx[4] + cx[5]) / 4) + offset;
+    offset = (CAL_DISTANCE * 3800) / 320;
+    config.ts_ytop    = ((cy[0] + cy[2] + cy[4] + cy[6]) / 4) + offset;
+    config.ts_ybottom = ((cy[1] + cy[3] + cy[5] + cy[7]) / 4) - offset;
+    TS_set_calibration(config.ts_xleft, config.ts_xright, config.ts_ytop, config.ts_ybottom);
+    write_config();
+
+    Buttons_Add(130, 200, 60, 40, "Ok", 0);
+    Buttons_Show();
+    while (1) {
+	vTaskDelay(20 / portTICK_PERIOD_MS);
+	if (Buttons_Scan() == 0) {
+	    return;
+	    break;
+    	}
+    }
+}
+
+