diff -r d8ace3fa9ac7 -r dc9281501ca6 www/ispindel/index.php
--- a/www/ispindel/index.php	Sun Mar 05 12:44:33 2023 +0100
+++ b/www/ispindel/index.php	Sat Aug 19 15:11:35 2023 +0200
@@ -7,8 +7,21 @@
 	$publisher = '/usr/bin/mosquitto_pub -h '.MQTT_HOST.' -t ';
 
 	$input = file_get_contents('php://input');
-	//syslog(LOG_NOTICE, "ispindel " . $input);
 	$data = json_decode($input, true );
+
+	if ($data['temp_units'] == 'K') {
+                $tempC = floatval($data['temperature']) - 273.15;
+        } else if ($data['temp_units'] == 'F') {
+                $tempC = floatval($data['temperature']) / 1.8 - 32;
+        } else {
+                $tempC = floatval($data['temperature']);
+	}
+
+	/* The rounding in the tilt using less digits results in a 0.25 plato difference. Calculate here again using the calibration data. */
+	$tilt = $data['angle'];
+	$plato = (0.00028548 * $tilt * $tilt * $tilt) + (-0.03492272 * $tilt * $tilt) + (1.617106176 * $tilt) + -21.412976092;
+	syslog(LOG_NOTICE, "ispindel " . $input . " plato ".$plato);
+
 	$node = 'ispindel-' . sprintf("%06x", floatval($data['ID']));
 
 	$alarm = 0;
@@ -33,18 +46,10 @@
 	if (floatval($data['battery']) < 3.3)
 		$alarm += 4;
 
-	if ($data['temp_units'] == 'K') {
-		$tempC = floatval($data['temperature']) - 273.15;
-	} else if ($data['temp_units'] == 'F') {
-		$tempC = floatval($data['temperature']) / 1.8 - 32;
-	} else {
-		$tempC = floatval($data['temperature']);
-	}
-
 	$uuid = 'c0ffeeee-cafe-dead-bee0-' . sprintf("%06x", 0xffffff - floatval($data['ID'])) . sprintf("%06x", floatval($data['ID']));
 	$topic = 'mbv1.0/ispindels/DBIRTH/' . $node;
 	$payload  = '{"unit":{"uuid":"' . $uuid .'","alias":"' . $data['name'] . '","alarm":' . $alarm . ',"interval":' . $interval;
-	$payload .= ',"angle":' . $data['angle'] . ',"temperature":' . $tempC . ',"battery":' . $data['battery'] . ',"gravity":' . $data['gravity'] . '}}';
+	$payload .= ',"angle":' . $data['angle'] . ',"temperature":' . $tempC . ',"battery":' . $data['battery'] . ',"gravity":' . $plato . '}}';
 	$pub = $publisher . $topic . ' -m \'' .$payload . '\'';
 	exec($pub);
 }