Detector Building C

[RiverWalker88]

Because this event has a test component, and it will be pretty heavily leaning on the test component, a question marathon is in order for Detector Building.

For more information on Question Marathons, see the overview here.
The Detector Building Forum can be found here.

A couple of easier questions to begin this marathon with:

1. What is the name of the equation that relates temperature with the resistance of a thermistor?
2. A really strange microcontroller has a 13-bit ADC.
   1. How many steps does this microcontroller have?
   2. If the input voltage is 5V, what is the step size?

[RiverWalker88]

RIP this marathon.

[Umaroth]

RIP this marathon.

Yikes I didn't notice lol

Click to Show Answer

1) Steinhart-Hart Equation Shhhhhhhhhhh
2) a) 8192
b) 0.610 mV

[RiverWalker88]

RIP this marathon.

Yikes I didn't notice lol

Click to Show Answer

1) Steinhart-Hart Equation Shhhhhhhhhhh
2) a) 8192
b) 0.610 mV

Thanks

Click to Show Answer

1. Yep
2.a. I think this one is 8191, because steps are just the jumps that can be made. (Or maybe I'm confused).
2.b. Yep

Your turn!

[ThomasL]

Here are some questions to get started again!

1. What happens to resistance as temperature increases for a) a conductor, and b) an insulator?
2. What is the use of a wheatstone bridge circuit?

I'm new to detector (coming over from circuit lab) and haven't taken too many tests yet--so looking forward to learning some things from the marathon

[RiverWalker88]

Here are some questions to get started again!

1. What happens to resistance as temperature increases for a) a conductor, and b) an insulator?
2. What is the use of a wheatstone bridge circuit?

I'm new to detector (coming over from circuit lab) and haven't taken too many tests yet--so looking forward to learning some things from the marathon

Welcome to the dark side.

Click to Show Answer

(Pretty sure these are right...)
1. As temperature increases, resistance increases for a conductor, and decreses for an insulator.
2. Given that you know the values of three resistors of the wheatstone bridge, you can very precisely determine the value of the fourth resistor.

[ThomasL]

Here are some questions to get started again!

1. What happens to resistance as temperature increases for a) a conductor, and b) an insulator?
2. What is the use of a wheatstone bridge circuit?

I'm new to detector (coming over from circuit lab) and haven't taken too many tests yet--so looking forward to learning some things from the marathon

Welcome to the dark side.

Click to Show Answer

(Pretty sure these are right...)
1. As temperature increases, resistance increases for a conductor, and decreses for an insulator.
2. Given that you know the values of three resistors of the wheatstone bridge, you can very precisely determine the value of the fourth resistor.

Looks good! Your turn. Also, thanks

[RiverWalker88]

Back to what I know best about this event. The code...

Below is a snippet of code from the loop function an arduino c++ detector program. In this case, the red LED is on digital output pin 1, the green LED on pin 2, and the blue LED on pin 3. The GetTemperature function will output the measured temperature of the water in degrees C. I haven't actually tested this code, and my C++ is a little rusty, so the syntax might be a little off, and the code might be a little broken... just a warning.

Code: Select all

    float temperature = GetTemperature(thermistor);
    float tBot[] = {22, 46, 12};
    float tTop[] = {39, 57, 70};
    
    for (int i = 0; i < 3; i++) {
        if (temperature > tBot[i] && temperature < tTop[i]){
            digitalWrite(i+1, HIGH);
        }
        else{
            digitalWrite(i+1, LOW);
        }
    }

1. What are the current temperature ranges entered for the detector?
2. Describe what the the purpose of the for loop in this program is.
3. Now, let's say at a competition, the red pin was moved to pin 4 because pin 1 was malfunctioning. Additionally, let the temperature ranges for this competition be red = 20*C to 56*C, green = 0*C to 25*C, and blue = 68*C to 75*C. Modify the code as little as possible so that the detector shows the proper LED ranges. You only need show the edited lines.

Edit: Just noticed that I messed up array initialization...

[ThomasL]

Click to Show Answer

a. Red is 22-39 C, green is 46-57 C, blue is 12-70 C
b. To update LED indicators based on measured temperature; if the temperature is within the designated range for the LED, light it up, else turn the voltage low.
c. 
float tBot[] = {0, 68, 20};
float tTop[] = {25, 75, 56};
// Then change i+1 in digital writes to i+2

Thanks for the question! Hope I got this right.

[RiverWalker88]

Click to Show Answer

a. Red is 22-39 C, green is 46-57 C, blue is 12-70 C
b. To update LED indicators based on measured temperature; if the temperature is within the designated range for the LED, light it up, else turn the voltage low.
c. 
float tBot[] = {0, 68, 20};
float tTop[] = {25, 75, 56};
// Then change i+1 in digital writes to i+2

Thanks for the question! Hope I got this right.

Yeah, all looks good. Your turn!