hello, @eboswort so the four pins are for the power connection and for debugging the CoDrone. If you access those pins using external sensors it is at your own risk. If accidentally connect the pins incorrectly you will be out of the warranty. The payload capability for CoDrone is roughly 7 grams so if the sensor is lighter than that you can place it there, however battery life will drop with the increased weight and power draw. One thing to note is the firmware on the CoDrone itself is not accessible to the public so you would need some other form of communication to send the temp data. Let me know if you have any other questions.