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12 MHz crystal and capacitors C1 and C2 form a series of working frequency generator oscilator AT89C2051, this series is a series of raw, meaning oscilator form of a series has always been like this for all circuits AT89C51, except for purposes other crystal values are probably different.
The combination of capacitors C3 and R8 detainees is also a series of materials, components used to form a series of 'power on reset', which means a circuit which will automatically reset every time AT89C2051 AT89C2051 start receiving electrical power source.
Looking at the circuit in Figure 1, it is inexplicable how this digital clock works, because the circuit was just part-timer button and the display of time, 'Hours' is actually a program that is stored in ROM in the IC AT89C2051.
To display the time used four 7 segment LED display units are formed with the IC2 and IC3 (each IC contains two digits display), thereby to display four digits of fruit needed 28 LEDs, if the LED 28 is lit extinguished in the normal way , we need 28 switches and circuit becomes very complicated. The commonly used way is seven segment display systems that are multiplex as apparent in Figure 1, while Figure 2 shows the details of this display system.
Each display digit LED is formed by seven pieces (Light Emitting Diode),
each diode segment is marked as 'a' through 'g', an anode of the seven LEDs
that have been linked together within the IC.
Cathode segment 'a' of tens of hours numbers associated with the cathode
segment 'a' from the number hours onwards.
Similarly, the segment 'b'; segment 'c' and so forth.
Ruas switch Q10 .. Q16 is used to determine which fields will be lit, for
example to form the number one then switch P11 (section b) and switch P12
(section c) in a position 'on'.
While Digits Scalar numbers are used to determine which view is used, for
example number one had wanted to appear on the display tens of hours, then
the scalar position in Q1.
If the position 'on' at Digit Switches rotate from Q1, Q2, Q3 and Q4 then go
back to Q1 and so quickly, then the number 1 above shall appear on all
display digits!
Next, suppose that before changing the switch position combinations Scalar
Field Digits set first, then the numbers that appear in the seven segment
display system can be adjusted accordingly.
Switches shown in Figure 1 is formed with a foot section P1.0 to P1.6
AT89C2051 feet, while the Digit Switches PNP transistor is formed with a
prisoner and a controlled passing each foot to foot P3.3 P3.0.
The process of setting the display system as discussed above, are governed
by AT89C2051 through discount programs are usually named as ScanDisplay as
follows:
Pieces of the
above program can be explained as follows: RuasJam10, RuasJam1, RuasMenit10
and RuasMenit1 a place to accommodate a combination of variable segments of
digits to be displayed, the contents of this variable will be changed in
other parts of the program in accordance with the changing times.
The contents of these variables is fed directly to Port 1 (row
2, 6, 10 and 14 at the discounted program above), for controlling the switch
section.
Digits
switch formed by PNP transistors, so for him the necessary voltage on the '0
'on one foot Port 3, as seen on lines 3, 7, 22 and 15. Notice the position
of the number '0 'on the fourth line, it would appear to '0' it was'jalan
'from left to right which is equivalent to rotating Digit Switches' on' from
Q1 until Q4.
TungguSebentar is a sub-routine which serves to delay time (delay), so the
numbers can be displayed immediately before the change stuck. On line 17,
the flow of the program in the switch back to the first row, so that the
pieces of this program will work continuously without stopping display of
numbers.
Jam Digital
Digital Clock in this project, indeed, the only form of the program. Basically, Digital Clock is counting system (counter)-story, starting from the chopping chopper minutes from 0 to 59 and overflow back to 0, and enumerators from 0 to 23 hours of chopping every time there is an abundance of counter-minute, this can be realized with following programs:...
