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029 if(flag==0)i++;

030 if(flag==1)i--;

031

032 if(i==255)flag=1;

033 else if(i==0)flag=0;

034

035 analogWrite(Backlight, i);

036

037 previousMillis = currentMillis;

038 }

039 }

The experiment also shows how an automatic up/down counter with

a limit can be put into practice. It is important that the

variable named

flag

receives a defined starting value of 0. When

starting the program, the variable

is counted up to 255 . If

we wanted to start at full brightness, we would have to initialise

the variable

flag

with 1 and the variable

with 255.

When the counter value

of 255 or 0 is reached, the varia-

ble

flag

will always be set from 0 to 1 or from 1 to 0 and the counter

direction will change (i++ increases the counter status, in-

cremented by 1, i-- reduces the counter status, decremented by

1). In the

Loop()

-function, we do not use a break this time, but

determine the time via the function

millis()

. Only when a specified

difference that we have declared in the variable

previousMillis

has

expired will the brightness be changed by one level. This way, the

program will continue to run at full speed outside of the

If()-query. Only if the PWM-value is changed will the throughput

time change a little, since some functions that require a certain

processing time will be called . Here, you can also try to

determine the different throughput times with

the

Millis()

-function that you have already learned about.

DOT-MATRIX-LCD

CLOCK

In many applications, a clock is needed for program control -

either a simple timer, a control to comply with a precise

schedule, or an operating hours counter. The applications that

need a clock are diverse.

The experiment shows how to program a very simple clock yourself.

The program runs in the

Loop()-

function, is finite and counts up

at a cycle of 10-ms. If the counter reading cnt = 100, the time