#include

#include

#include

#include "qutyserial.h$"$

$/**$ Tutorial $08$

INTRODUCTION:

In this week's tutorial you will use TCA$0$ and ADC$0.$ You will use these

peripherals 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: $8\mathrm{.}0$

TASK: Write a function named $"$pwm$\_$init" which will configure TCA$0$ to

produce a

$3$X$0$ Hz$,1$Y $\%$ 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 was n$12345678$ then you should configure

TCA$0$ to produce a

$370$ Hz$,18\%$ duty cycle output on the DISP EN net.

$*/$

$/**$ CODE: Write your code for Ex $8\mathrm{.}0$ above this line. $*/$

$/**$ EX: $8\mathrm{.}1$

TASK: Write a function named "adc$\_$init" below which will configure

ADC$0$ 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 $8\mathrm{.}1$ above this line. $*/$

int main$($void$)$

$\{$

$//$ Variable to store the result of the ADC conversion

uint$8\_$t result;

serial$\_$init$()$;

PORTA.DIRSET $=$ PIN$1\_$bm;

PORTA.PIN$7$CTRL $=$ PORT$\_$PULLUPEN$\_$bm;

$/**$ EX: $8\mathrm{.}2$

TASK: Call the two initialisation functions you have written above

such that the TCA$0$ and ADC$0$ are enabled and operational.

On completion of this exercise, the $7-$segment display should show

a dimly lit $8$ on the RHS$.$

You can then test your ADC configuration via the serial terminal

using the instructions below.

$*/$

$/**$ CODE: Write your code for Ex $8\mathrm{.}2$ above this line. $*/$

printf$("$Turn the potentiometer R$1$ fully counter$-$clockwise, then press S$4.$

$")$;

while $($VPORTA$.$IN & PIN$7\_$bm$)$; result $=$ ADC$0.$RESULT$0$; printf$("$Ex $8\mathrm{.}2\mathrm{.}0$: result $=0$x$\%02$X$,$ expected $=0$x$00$

$",$ result$)$;

printf$("$Turn the potentiometer R$1$ fully clockwise, then press S$4.$

$")$;

while $($VPORTA$.$IN & PIN$7\_$bm$)$; result $=$ ADC$0.$RESULT$0$; printf$("$Ex $8\mathrm{.}2\mathrm{.}1$: result $=0$x$\%02$X$,$ expected $=0$xFF

$",$ result$)$;

printf$("$Turn the potentiometer R$1$ to the half$-$way position, then press S$4.$

$")$;

while $($VPORTA$.$IN & PIN$7\_$bm$)$; result $=$ ADC$0.$RESULT$0$; printf$("$Ex $8\mathrm{.}2\mathrm{.}2$: result $=0$x$\%02$X$,$ expected $=0$x$80$

$",$ result$)$;

$//$ Main loop

while $(1)$

$\{$

$/**$ EX: $8\mathrm{.}3$

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: ADC$0.$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.

HINTS:

$1.$ Scale the $8-$bit value from ADC$0.$RESULT to a value between $0$

and the TOP value of TCA$0.$

$2.$ Reverse the direction of the potentiometer by subtracting the

scaled value from the TOP value of TCA$0.$

Alternatively,

$1.$ Reverse the direction of the potentiometer by subtracting the

$8-$bit value from ADC$0.$RESULT from $255.$

$2.$ Scale the reversed value to a value between $0$ and the TOP

value of TCA$0.$

TIPS:

$-$ Avoid floating$-$point arithmetic by using integer

approximations.

$-$ Some integer operations should be performed before others to

prevent loss of precision.

$-$ Recall type conversion rules when using arithmetic operators.

$*/$

$/**$ CODE: Write your code for Ex $8\mathrm{.}3$ above this line. $*/$

$/**$ EX: $8\mathrm{.}4$

TASK: Write code below to drive the buzzer when the

potentiometer's position is between $87\mathrm{.}5\%$ 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 buzzer will produce the frequency specified in Ex $8\mathrm{.}0.$

$*/$

$/**$ CODE: Write your code for Ex $8\mathrm{.}4$ above this line. $*/$

$\}$

$\}$