Debugging

Debugging

The following are bits of advice and experience we have come across to help work through problems

SI7021

Getting the the sensor up and running has caused problems for a number of people. In general, it is usually a hardware problem and not a software problem. The software (SI7021.py) has a built in test function which can be run from a command prompt:

python /home/pi/MVP/python/SI7021.py

You should see both sensor readings, as well as information about the sensor (version, etc). At a lower level, you can install the i2cdetect package, which will list all of the I2C devices that are available.

sudo apt-get install i2c-tools

Then from the command prompt run:

sudo i2cdetect -y 1 (or possibly: sudo i2cdetect -y 0)

This will display a grid of all possible addresses, and show the number of working i2c sensors. The SI7021 should show up as address 40.

If the sensor does not show up, you have a hardware problem (or have not enabled I2C on the Raspberry.

• Check the Raspberry Configuration and confirm that I2C is enabled.
• Check you wiring that you have the proper pins connected
• Check you header pin soldering
• If you know someone with a working system, try swapping sensors (will check if the sensor and sensor soldering is good)