6. Electronic Design – Andrew and Kathryn¶
Our group assignment was to use the test equipment in our lab to observe the operation of a microcontroller circuit board. We covered the multimeter and oscilloscopes.
Work Distribution¶
| Member | Role |
|---|---|
| Andrew and Kathryn | Documentation |
| Kathryn | Sigilent Oscilloscope |
| Kathryn | Multimeter |
| Andrew | Analog Discovery 2 |
Oscilloscope - Kathryn¶
For the oscilloscope, we first wired a breadboard using an RP2040 chip to make an LED fade in and out.
We then attached the oscilloscope’s alligator clip to the anode (positive leg) of the LED. This allowed us to observe the PWM (pulse-width modulation) signal as square waves on the oscilloscope screen. As we modified the code to increase the frequency of the PWM signal, the observed square waves on the oscilloscope displayed faster cycles, corresponding to the higher frequency.
Originally, I expected the oscilloscope to display something more like a sine wave. But later it made more sense to be a square wave because PWM is a digital switching signal with abrupt transitions, having only two voltage states: high and low. On the other hand, a sine wave represents a smooth, continuous variation in voltage.
Andrew played around with some settings and got the mean value, voltage, to show up.
We then tried to use a potentiometer to manually control the pulse width, the curve seemed to be more sinusoidal.
Multimeter - Kathryn¶
We used the multimeter throughout the oscilloscope process in two instances. First was to check the continuity of the RP2040 pins.
The second measurement was of the voltage. Since we were using PWM, we expected the measured voltage to oscillate between high and low levels in accordance with the duty cycle of the signal, which it did. It also aligned with the mean value as seen on the oscillometer, which it should.
Logic Analyzer Discovery 2 - Andrew¶
A logic analyzer is a tool used in electronics to capture, store, and analyze digital signals from a circuit, helping to debug and troubleshoot hardware issues. It samples multiple signals simultaneously, storing the data in memory, and displays the waveforms on a screen, showing the state of each signal over time. Key features include the number of channels it can monitor, the sampling rate, memory depth, and triggering capabilities, which help identify timing issues, glitches, or unexpected behaviors. It’s invaluable in developing new hardware or diagnosing existing systems. This week we used our Discover 2 logic analyzer as an Oscilloscope and looked at the I/O Pin signals.
To use the oscilloscope in the logic analyzer we downloaded the Waveforms software here and used C1+ as our positive and C1- as our negative. Then we looked at the PWM of the LED.
We also looked at the I/O pin reader. We examined the Button and LED pin with this feature. To do this we created a parallel circut from each pin to the Logic analyzer, then back to ground. Even though one of th epins were connected to a button, we found that setting it to a button made it so that the logic analyzer wouldn’t read the pin, instead, this setting would make a virtual button that would send a signal to our chip.
