Update #1: Minor bug fix in the Calibration routine -> v1_1b This are two enhancements for the plot thermometer / clock http://www.thingiverse.com/thing:371248 Such a plot thermometer / clock is a cool stuff but you can't use it for long time as the pen gets empty (or even drys out). This two enhancements makes that it plots only if it is really required: PIR sensor: if someone is in the room Button: If you press the button One or the other can be attached to the plot thermometer/clock to the interface on the right side. With the PIR sensor it plot as long it detects someone, with the button it prints once when the minute changed. As its also not good to let dry the ink on the board it cleans up the board one minute after nobody is in the room. If you don't attach whether button or PIR sensor it runs normal and writes time or temperature every minute The PIR Sensor is a HC-SR501 you might find everwhere The tactil switche is from SparkfunCOM-10302