add keller pressure decoder

keller-pressure/decoder.js

@@ -0,0 +1,79 @@
+/**
+ * TTN-compatible data decoder for the Lobaro LoRaWAN Humidity Sensor.
+ *
+ * For the current version of this and other data formats check out:
+ * https://github.com/lobaro/ttn-data-formats/
+ *
+ * For more information go to:
+ * https://www.lobaro.com/
+ *
+ *
+ * MIT License
+ *
+ * Copyright (c) 2018 Lobaro
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+function decodeFloat32(bytes) {
+ var sign = (bytes & 0x80000000) ? -1 : 1;
+ var exponent = ((bytes >> 23) & 0xFF) - 127;
+ var significand = (bytes & ~(-1 << 23));
+
+ if (exponent == 128)
+ return sign * ((significand) ? Number.NaN : Number.POSITIVE_INFINITY);
+
+ if (exponent == -127) {
+ if (significand == 0) return sign * 0.0;
+ exponent = -126;
+ significand /= (1 << 22);
+ } else significand = (significand | (1 << 23)) / (1 << 23);
+
+ return sign * significand * Math.pow(2, exponent);
+}
+
+function decodeInt16(bytes) {
+ if ((bytes & 1 << 15) > 0) { // value is negative (16bit 2's complement)
+ bytes = ((~bytes) & 0xffff) + 1; // invert 16bits & add 1 => now positive value
+ bytes = bytes * -1;
+ }
+ return bytes;
+}
+
+function int16_LE(bytes, idx) {
+ bytes = bytes.slice(idx || 0);
+ return bytes[0] << 0 | bytes[1] << 8;
+}
+
+function int32_LE(bytes, idx) {
+ bytes = bytes.slice(idx || 0);
+ return bytes[0] << 0 | bytes[1] << 8 | bytes[2] << 16 | bytes[3] << 24;
+}
+
+function Decoder(bytes, port) {
+ // Decode an uplink message from a buffer
+ // (array) of bytes to an object of fields.
+ var decoded = {
+ pressure: decodeFloat32(int32_LE(bytes, 0)),
+ temp: decodeInt16(int16_LE(bytes,4)) / 100,
+ };
+
+ // if (port === 1) decoded.led = bytes[0];
+
+ return decoded;
+}