TTN Smart Sensor (Noah)

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 function decodeUplink(input) { // Decode an uplink message from a buffer // (array) of bytes to an object of fields. var decoded = {}; var bytes = input.bytes; // temperature rawtemp = bytes[0] + bytes[1] * 256; decoded.temp = sflt162f(rawtemp) * 100; // humidity decoded.voltage = bytes[2] + bytes[3] * 256; // = sflt162f(rawvolate) * 100; rawdis = bytes[4] + bytes[5] * 256; decoded.level = sflt162f(rawdis) * 100; return {data: decoded}; } function sflt162f(rawSflt16) { // rawSflt16 is the 2-byte number decoded from wherever; // it's in range 0..0xFFFF // bit 15 is the sign bit // bits 14..11 are the exponent // bits 10..0 are the the mantissa. Unlike IEEE format, // the msb is transmitted; this means that numbers // might not be normalized, but makes coding for // underflow easier. // As with IEEE format, negative zero is possible, so // we special-case that in hopes that JavaScript will // also cooperate. // // The result is a number in the open interval (-1.0, 1.0); // // throw away high bits for repeatability. rawSflt16 &= 0xFFFF; // special case minus zero: if (rawSflt16 == 0x8000) return -0.0; // extract the sign. var sSign = ((rawSflt16 & 0x8000) != 0) ? -1 : 1; // extract the exponent var exp1 = (rawSflt16 >> 11) & 0xF; // extract the "mantissa" (the fractional part) var mant1 = (rawSflt16 & 0x7FF) / 2048.0; // convert back to a floating point number. We hope // that Math.pow(2, k) is handled efficiently by // the JS interpreter! If this is time critical code, // you can replace by a suitable shift and divide. var f_unscaled = sSign * mant1 * Math.pow(2, exp1 - 15); return f_unscaled; }