Part A. Writing to the Serial Monitor
a. Based on the readings from the serial monitor, what is the range of the analog values being read?
0-1023
b. How many bits of resolution does the analog to digital converter (ADC) on the Atmega32U4 have [hint: where might you look to find this sort of thing]? How many are you using with the range of values you're seeing?
10 bit ADC according to the datasheet. We are using all 10 bits because we get a range from 0 to 1023 in increments of 1, meaning 2^10 gradations, meaning 10 bits.
Part B. Voltage Varying Sensors
1. IR Distance Sensor
a. Describe the voltage change over the sensing range of the sensor. A sketch of voltage vs. distance would work also. Does it match up with what you expect from the datasheet?
Experimentally: 20 mV to 2.4 V. Difference = 2.4V.
Datasheet: .4 V to 3.1 V. Difference = 2.7V
2. Accelerometer
a. Include your accelerometer read-out code in your write-up.
#include <LiquidCrystal.h>
// these constants describe the pins. They won't change:
const int xpin = A3; // x-axis of the accelerometer
const int ypin = A2; // y-axis
const int zpin = A1; // z-axis (only on 3-axis models)
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup()
{
// initialize the serial communications:
Serial.begin(9600);
lcd.begin(16,2);
}
void loop()
{
int x = analogRead(xpin);
int y = analogRead(ypin);
int z = analogRead(zpin);
lcd.clear();
lcd.print("x y z");
lcd.setCursor(0, 1);
lcd.print(x);
lcd.setCursor(6, 1);
lcd.print(y);
lcd.setCursor(12, 1);
lcd.print(z);
delay(100);
}
Part C. Count/Time-Based Sensors
a. Upload a picture of your rotary encoder in action!
Part D. Logging values to the EEPROM and reading them back
1. Design your logger
a. Turn in a copy of your final state diagram.
DDR State Diagram:
2. Reading and writing values to the EEPROM
a. How many byte-sized data samples can you store on the Atmega32U4?
-1024
b. How would you get your analog data from the ADC to be byte-sized?
-Round it down to 8 bit precision: 0-255.
3. Create your data logger!
a. Use the lab camera or your own camera/cell phone to record and upload a short demo video of your logger in action.
b. Post a link to the Lab 4 Data Logger Hall of Fame.
DDR Code: