Equipment: Arduino UNO, PC with IDE, Prototyping components, and wires.

In the Arduino we can look inside registers by looking at the contents of the Port Registers. Port registers allow for lower$-$level and faster manipulation of the i$/$o pins of the microcontroller on an Arduino board. The chips used on the Arduino UNO board have three ports:

B $($digital pin $8$ to $13)$

C $($analog input pins$)$

D $($digital pins $0$ to $7)$

Each port is controlled by three registers, which are also defined variables in the IDE Language.

DDR register: determines whether the pin is an INPUT or OUTPUT.

PORT register: controls whether the pin is HIGH or LOW,

PIN register: reads the state of INPUT pins set to input with pinMode$().$

DDR and PORT registers may be used for read $/$ write.

PIN registers correspond to the state of inputs and may only be read.

Port Mapping:

PORTD maps to the Arduino digital pins $0$ to $7$

DDRD $$ The Port D Data Direction Register $$ read$/$write

PORTD $$ The Port D Data Register $$ read$/$write

PIND $$ The Port D Input Pins Register $$ read only

PORTB maps to Arduino digital pins $8$ to $13$ The two high bits $(6$ & $7)$ map to the crystal pins and are not usable

DDRB $$ The Port B Data Direction Register $$ read$/$write

PORTB $$ The Port B Data Register $$ read$/$write

PINB $$ The Port B Input Pins Register $$ read only

PORTC maps to Arduino analog pins $0$ to $5.$

DDRC $$ The Port C Data Direction Register $$ read$/$write

PORTC $$ The Port C Data Register $$ read$/$write

PINC $$ The Port C Input Pins Register $$ read only

Each bit of these registers corresponds to a single pin; e$.$g$.$ the low bit of DDRB$,$ PORTB, and PINB refers to pin PB$0($digital pin $8)$ Modify your code developed for the LED portion to display the letters on the $7$ segment LED.

Here is a start:

$//$ First: Identify the digital pin to a pin on the LED

int b$=6$;

int c$=5$;

$//$ Procedure to display number $1$

void display$1($void$)$

$\{$ digitalWrite$($b$,$HIGH$)$;

digitalWrite$($c$,$HIGH$)$; $\}$

void loop$()$

$\{$

clearDisplay$()$;

display$1()$; $\}$