Week 8 - Electronics Design: Connor, Angelina, and Kabir¶
Observing boards in operation¶
Oscilloscope¶
Assignment¶
-
Use the test equipment in your lab to observe the operation of a microcontroller circuit board
-
Document your work on the group work page and reflect what you learned on your individual page
Using the Multimeter¶
For our multimeter testing, we used a Kabir Nawaz’s blink board (target), connecting it and programming it through the QuenTorres. We uploaded this dimming code using a PWM (pulse width modulation) pin, selecting ATtiny412 as the chip under MegaTinyCore:
#define ledPin PIN_PA7
void setup() {
pinMode(ledPin, OUTPUT);
}
uint8_t count = 1;
void loop() {
analogWrite(ledPin, ++count);
delay(5);
}
Here is what the LED looked like with the dimming code:
Measuring Current¶
To measure the current, we switched the knob to mA (milliamps) and changed the probe plug-in accordingly. After connecting the probes to the PWR and GND jumperwires, we found that the drive current as about 15 mA.
Measuring a Constant Voltage¶
To use the multimeter, we first rotated the knob to Volts and ensured that the probes were in the correct holes, which were indicated by light. Placing the red probe on the VCC pin and the black probe on GND, we measured the constant voltage that was supplied to the chip itself. This read approximately 5 V.
Measuring voltage from a PWM pin¶
To get a snapshot of how the voltage changes for an LED that dims and brightens, we touched the red probe to the trace of pin ~1 and the black probe to GND. On the multimeter, we could see that the voltage consistently jumped from lower to higher values.
Although this displays the varying voltage levels and how it directly affects the LED’s brightness, it doesn’t give the full picture, unlike the oscilloscope.
Using the Oscilloscope¶
To get a better idea of how the voltage changes, we can looked towards an oscilloscope, which visually displays how electrical signals change over a period. Using the SDS 1202X-E oscilloscope in the lab, we plugged in the probe and ran the auto-setup to callibrate them. Then, adjusting the unit increments for voltage, we placed the probes on the same locations as before. When looking at the display, we could see how the LED’s voltage kept increasing in length for a short period, before decreasing, which directly relates to the growing/dimming brightness of the LED.