#include
#include
#include
#include
#include “qutyserial.h”
/** Tutorial 08
INTRODUCTION:
In this week’s tutorial you will be working with the TCA0 and
ADC0 peripherals. You will use these to control the brightness
of the 7-segment display, produce a tone from the buzzer, and
read the position of the potentiometer.
Interfacing with these hardware devices on the QUTy is a core
requirement for Assessment 2.
/** EX: 8.0
TASK: Write a function named “pwm_init” which will configure
TCA0 to produce a
3X0 Hz, 1Y % duty cycle output on the DISP EN net.
Where XY are the last two digits of your student number.
Your function should take no arguments and return no values.
EXAMPLE: If your student number were n12345678 then
you should configure TCA0 to produce a
370 Hz, 18 % duty cycle output.
/** CODE: Write your code for Ex 8.0 above this line. */
/** EX: 8.1
TASK: Write a function named “adc_init” below which will configure
ADC0 in 8-bit single conversion mode.
The ADC should be configured to sample the voltage on the POT net,
be placed in free-running mode, and start sampling immediately.
/** CODE: Write your code for Ex 8.1 above this line. */
int main(void)
// Variable to store the result of the ADC conversion
uint8_t result;
serial_init();
PORTA.DIRSET = PIN1_bm;
PORTA.PIN7CTRL = PORT_PULLUPEN_bm;
_delay_ms(3000); // 3 second delay
/** EX: 8.2
TASK: Call the two initialisation functions you have written above
such that the TCA0 and ADC0 are enabled and operational.
On completion of this exercise, the 7-segment display should show
an 8 on the RHS that is initially bright, but dims after 3 seconds.
You can then test your ADC configuration via the serial terminal
using the instructions below.
/** CODE: Write your code for Ex 8.2 above this line. */
printf(“Turn the potentiometer R1 fully counter-clockwise, then press S4.\n”);
while (VPORTA.IN & PIN7_bm); result = ADC0.RESULT0; printf(“Ex 8.2.0: result = 0x%02X, expected = 0x00\n”, result);
_delay_ms(1000); printf(“Turn the potentiometer R1 fully clockwise, then press S4.\n”);
while (VPORTA.IN & PIN7_bm); result = ADC0.RESULT0; printf(“Ex 8.2.1: result = 0x%02X, expected = 0xFF\n”, result);
_delay_ms(1000); printf(“Turn the potentiometer R1 to the half-way position, then press S4.\n”);
while (VPORTA.IN & PIN7_bm); result = ADC0.RESULT0; printf(“Ex 8.2.2: result = 0x%02X, expected = ~0x80\n”, result);
// Main loop
/** EX: 8.3
TASK: Write code below such that the position of the potentiometer
controls the brightness of the 7-segment display in reverse.
The display should be:
– fully bright when the potentiometer is turned fully counter-clockwise
– fully dim when the potentiometer is turned fully clockwise
NOTE: ADC0.RESULT yields a value of 0 when the potentiometer is turned
fully counter-clockwise, and a value of 255 when turned fully clockwise.
You will need to reverse this range of values using a mathematical
expression to achieve the desired functionality.
1. Scale the 8-bit value from ADC0.RESULT to a value between
0 and the TOP value of TCA0.
2. Reverse the direction of the potentiometer by subtracting the
scaled value from the TOP value of TCA0.
Alternatively,
1. Reverse the direction of the potentiometer by subtracting the
8-bit value from ADC0.RESULT from 255.
2. Scale the reversed value to a value between 0 and the TOP
value of TCA0.
TIP: Avoid floating-point arithmetic by performing integer operations.
To ensure that you do not encounter integer overflow and loss of precision,
perform operations in an appropriate order.
/** CODE: Write your code for Ex 8.3 above this line. */
/** EX: 8.4
TASK: Write code below such that the buzzer produces a 3X0 Hz tone
when the potentiometer position is between 87.5% and 100%, where
0% is fully CCW and 100% is fully CW.
When the pot position is outside of this range the buzzer should be silent.
The buzzer should be driven with a
– 50 % duty cycle square wave when active
– 0 % duty cycle square wave when inactive
TIP: You will need to modify the code in pwm_init() to achieve this functionality.
NOTE: The frequency specified above is the same as for Ex 8.0.
/** CODE: Write your code for Ex 8.4 above this line. */