prioritise checksum

GLinnik21 · Aug 25, 2023 · 38a2609 · 38a2609
1 parent 33d584e
commit 38a2609
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/lib/mh_z19_uart_tools/mh_z19_uart_tools.c b/lib/mh_z19_uart_tools/mh_z19_uart_tools.c
@@ -80,11 +80,11 @@ void mh_z19_uart_switch_detection_range(MhZ19DetectionRange range, uint8_t* comm
 }
 
 int16_t mh_z19_decode_co2_concentration(const uint8_t* data) {
-    if(data[1] != MhZ19UartCommandCO2Concentraion) {
-        return -1; // Invalid command
-    }
     if(data[8] != mh_z19_uart_checksum(data)) {
         return -2; // Invalid checksum
     }
+    if(data[1] != MhZ19UartCommandCO2Concentraion) {
+        return -1; // Invalid command
+    }
     return (data[2] << 8) | data[3];
 }