8 June 15

We created the thermistor circuit on June 4 and wrote the code to read it.  We constructed the circuit so that the resistance of the thermistor decreases as the temperature increases. See the June 4 entry for the formula we used to read the voltage.  Our code can be found at https://github.com/bccBalloon/HiBalloon. We also soldered thermistor to our circuit board.

We will work on attaching the ribbon cable to the circuit board and also work on calibrating the accelerometer.

Notes on constructing the payload.

A Beaglebone Black Rev C is used for powering the payload sensors.  The senosrs include a barometer, accelorometer, magnotometer, and thermister.

We are using the ADXL335 3-axis accelorometer with breakout board. Two 470 kOhm resistors are used for each axis output pin.  This serves the function of halving the output voltage, since the Beaglebone Black can only read up to 1.8 V in it's analog pins.  In addition, the accelorometer has an internal 32 kOhm resistor and we didn't want the entire voltage drop in the accelerometer.