11. Input Devices: Landon Broadwell and Alana Duffy¶
Assignment:
- Probe an input device’s analog levels and digital signals.
The goal of the group project this week was to test one of our group member’s input device to check the analog or digital signals, where applicable. Our group consisted of Landon Broadwell and Alana Duffy. We chose to use Landon’s BNO-055 9-axis DOF sensor.
I2C¶
First, we measured the I2C connection signals of the sensor. After setting up the oscilloscope by plugging the probe into the first port and selecting “Auto Setup,” we hooked up the probe to the SDA pin of the sensor board and the alligator clip to the SCL pin of the sensor board. At first, it was very difficult to get a reading on the oscilloscope, since, as we could see on the OLED, it would turn off/malfunction if one of the two pins became disconnected. We were able to eventually get a successful reading, however.
This video shows a bit off an odd display, with many different lines appearing that have different shapes, with most converging back to the main central line. We believed that it displayed the different signals from the sensor being sent, as though they did not change when the sensor was moved, the multitude of them reflects the different data types that were being sent and the pulsing of the signal lined up with the intervals at which the data was being read and sent to the OLED in the code.
Voltage¶
Next was to measure the power of the sensor, once again using the oscilloscope, but this time on the power and ground pins of the sensor. We did the same style of connections, but when the readings didn’t give us anything, we had to adjust the different settings on the side of the oscilloscope with the knobs to get the correct readings.
While unsure of what the sinusoidal appearance of this graph meant, we knew that the value of this reading, which can not be seen very well in the video, was from 1.3-1.8V. This seemed somewhat accurate to the datasheet, though, again, we were not fully confident in the results.