For our Datalogging assignment, Lia and I chose Parallax’s CH4 (methane) Sensor Module. The module is specifically designed to determine whether a preset level of methane gas is surpassed. The module uses a MQ-2 methane sensor, which, when heated by an applied voltage (5V), reduces its internal resistance, and hence its output voltage, in relation to the level of methane gas present in the air. The module provides circuitry to set a trigger voltage to sound an alarm for when a specific level of methane is surpassed. For this assignment, we ignored the alarm circuitry and monitored the output voltage of the sensor.
I thought I’d try out my new XBees with the ADXL335 accelerometer I had on hand to make a 3-axis accelerometer visualization. I borrowed from project 21 in Tom’s Making Things Talk, but taped the accelerometer at the center of a frisbee (level to the frisbee’s orientation plane), along with an Arduino and an XBee. I added 4 LEDs: 2 placed on the two points where the x-axis of the accelerometer intercepts with the frisbee’s circumference and 2 on where the y-axis intercepts. I then programed the Arduino to illuminate the LEDs which corresponded to positive pitch or roll. I added an XBee to make it wireless and transmitted the acceleration (in gs) of the three axes, along with the pitch and yaw. I used processing to sketch a visualization of this data. The ellipses in the graph move vertically along their acceleration (in gs) axes. The orientation of the disc in the center (representing the frisbee) corresponds with the calculated pitch and roll of the accelerometer.