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What is MR PLOW and how do you use it?

The basic application of this amazing device is to check, if it is safe or not to go skiing/snowboarding/free riding. You put MR PLOW on you ski/snowboard point it down the hill with the estimated angle of the ski run, press a button and see how dangerous it is to set off an avalanche. The information to get a precise assessment is collected from the altimeter, compass, accelerometer (tilt compensation and angle) and temperature sensor. For a real use of the device you will need some more information. Therefore a RF transmitter at the exit point of the ski lift would be mounted. This device could be realized with an Anaren Booster Pack and a MSP430. This “Info Point” is sending the actual altitude, the deviation of the factual North Pole (this value is dependent of the geographical location) and of course the heading of the compass direction with its risk level.


  • Felix Filchner
  • Philipp Reiter (


  • Low Power Mode (Power consumption is higher than expected because of the separate LDOs on the sensor development boards)
  • RoHS Compliance: Altimeter (MS5607-02BA01), compass (HMC5883L), MSP430FR5739, ADXL335, A1101RL09A
  • actual use of watchdog (if the device is in idle for more than 4 minutes, the device is going into a low power mode to save battery power)
  • temperature sensor
  • tilt sensor
  • compass sensor
  • error detection (wrong temperature sensor value, pressure sensor value, mode Input -> reset to normal mode; PROM read error -> shutdown of the device, critical error)

Usage Instructions

We used for this application two sensors with an I2C interface. Both Sensors are available from Parallax. Altimeter Sensor MS5607 (Parallax item code: 29124) and Compass module HCM5883L (Item code: 29133). To connect these two devices you need the I2C interface on the Fraunchpad Pin 1.6 (SDA) and Pin 1.7 (SCL). The pull up resistors are already on the boards. On the compass module you will need only VIN/GND/SDA/SCL on the altimeter module you’ll need GND/VIN/SDA/SCL/CS (VIN-Level)/PS (VIN-Level). Don’t worry about the two sets of the pull up resistors it still works. For the connection of these two boards we build a simple adapter board with some connectors and wires. We used for the VIN the external power supply pin near the push Buttons S1 and S2.

Now you have to build everything together and build the software with CCS 5.3

When you have done this, it’s pretty simple to use it. You have to select one of four different modes. With button S1 you can select the mode and the current status of your input is represented by LEDs. Confirm your selection with button S2. If your Input was wrong the wrong Input LED will flash up and you can start again.

  1. Mode: Tilt sensoring. The first LED indicates the sign of the declination the other LEDs show you the value in a binary form (7digits= +/- 90 degree)
  2. Mode: Use the device as a normal compass. The LEDs give you the information in which direction the arrow is pointing.
  3. Mode: This mode is for temperature. It is the same reading as mode one. First LED for sign and the other 7 for the value in binary form
  4. Mode: Point your device with the arrow down the hill. And press the left button. The device checks the direction (north/south/east/west) and downhill slope. It even considers the altitude of your location. If the conditions are too bad all 8 LED are flashing and warns you that you shouldn’t go. If only the first LED is on it’s pretty safe to go for a ride. More LEDs more dangerous :-)

LED Info table: LED table

Optional (future plans)

  • add the RF module for syncing/receiving data
  • add logging function for altimeter and accelerometer (mount device on ski/snowboard to see how fast you were and how enormous the stress was, read the data with your PC using the RF connection)
  • add a low power ePaper Display for easier information reading


Sketchup model: Dimenson of the board: 2x3 inch ( 77x52 mm)

Pictures of the dev board

Video of the code running on the dev board:

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Source Code

File:MR PLOW Flowchart.pdf


File:MR PLOW schematic.pdf