Hardware Diagnostics - mcgill-robotics/auv-embedded-2026 GitHub Wiki
It's important to be able to use the appropriate tools to diagnose and prevent hardware problems. Here's a quick summary of basic tools we have in the workshop that are helpful for your use.
Tools
1. Multimeter (Sanity Checks)
- Continuity Mode ($\Omega$ / Beep): Use this before applying power. Touch the probes together to hear the beep. Use it to ensure GND and 5V are not connected (a short). You can also check if something that should be connected actually is.
- Voltage Mode (V⎓): Check voltage outputs. Always connect the black probe to GND and the red probe to the test point.
- Resistance Mode ($\Omega$): Verify resistor values.
- Diode Mode ( $\rightarrow |$ ): Connect probes on either side of an LED to check polarity.
[!TIP] Safety First: Always double-check your multimeter lead positions. Plugging probes into the Amperage (A) port while trying to measure Voltage (V) will blow the internal fuse (or worse).
2. The Oscilloscope (Analog Signal Monitoring)
- Use for seeing exactly what's happening in a circuit over time.
- On the display, the vertical axis is Voltage and the horizontal axis is time.
- All signals need to be referenced to ground. Attach probe to signal you want and the secondary clip to ground.
3. Logic Analyzer (Digital Signal Translation)
- Translates voltage high and voltage low into 1s and 0s
- Vertical axis is logic value (1 or 0) and horizontal axis is time
- Can often decode specific communication protocols, i.e. UART
Tool Selection Guide
| If you want to know... | Use a... | Methodology |
|---|---|---|
| "Is this wire broken?" | Multimeter (Continuity) | Look for the Beep icon; touch probes together to verify. |
| "Is this LED backwards/dead?" | Multimeter (Diode Mode) | Red to Anode, Black to Cathode; LED will light up in correct orientation |
| "Is my battery at 14.8V?" | Multimeter (DC Voltage) | Set to V⎓; Red to Red, Black to Black; ensure black lead is in the COM port. |
| "Is my Teensy pin fried?" | Multimeter (Diode Mode) | Red to GND, Black to Pin; a reading of 0V means a short. |
| "Is my Ethernet signal healthy?" | Oscilloscope (Math) | Probe $TX+$ and $TX-$; use CH1 - CH2 to see the differential signal. |
| "Is my PWM pulse exact?" | Logic Analyzer | Use timing markers to verify the 1100µs - 1900µs T200 pulse width. |
| "What is the Teensy saying?" | Logic Analyzer | Connect to TX/RX; use laptop software to decode UART/Serial data. |