Fixed negative temperature bug.

CHANGELOG.md

@@ -57,3 +57,8 @@ First (more or less) working version.
 
 ### Fixed
 - One of the digital outputs was inverted.
+
+## [1.1.2] - [2024-01-08]
+
+### Fixed
+- Negative temperature where converted wrong: -1 became -32767. This was because of a weird format the sensor uses.

src/main.cpp

@@ -758,6 +758,12 @@ int main() {
         if (!NO_I2C_AVAILABLE)
             ReadAM2315(&humidity, &temperature);
 
+        // Bit 15 of AM2315 temperature is sign (1 = negative). Bit 14-0 is absolute value of teperature
+        if (temperature&0x8000) {
+            temperature = temperature & 0x7FFF; // remove sign bit
+            temperature = -temperature;         // make proper signed integer of negative number
+        }
+
         // Format telemetry string
         sprintf(tmp_string, "%.1f,%.1f", (float)temperature/10, (float)humidity/10);
         // Copy string (including NULL terminator) to final destination (can not be done without temporary string due to char/uint8_t issues)