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International Journal of Electronics, 
Communication & Instrumentation Engineering 
Research and Development (IJECIERD) 
ISSN(P): 2249-684X; ISSN(E): 2249-7951 
Vol. 4, Issue 2, Apr 2014, 137-148 
© TJPRC Pvt. Ltd. 


THE USE OF MICROSOFT EXCEL TO SIMULATE THE CHARGING CAPACITOR (C) 
THROUGH A RESISTANCE (R), AND CALCULATING THE APPROPRIATE VALUE OF T 
(RC) OF 8051 MICROCONTROLLER RESET CIRCUIT 

DAHLAN RP SITOMPUL & POLTAK SIHOMBING 

University of North Sumatera (USU) and ATI Immanuel, Faculty of Computer Science and Information Technology, 

Medan, North Sumatra, Indonesia 



ABSTRACT 


On this occasion, the author would like to discuss the use of Microsoft Excel to simulate the charging of the 
capacitor (C) through a resistance (R) of the 8051 microcontroller reset circuits m . The author would also shows the 
equation (rule of thumb) to calculate the appropriate value of t (RC) used to form the 8051 microprocessor reset circuit and 
using the table and the graph obtained from Microsoft Excel to opt the proper RC value. 

KEYWORDS: 8051 Microprocessor Reset Circuits, TTL (Transistor Transistor Logic) Voltage Range 

INTRODUCTION 


Due to a lot of student that forwarded inquiries at my microprocessor / microcontroller class and electronics 
enthusiasts on the blog [31 asked technique or method to calculate the values of the resistor and capacitor of microcontroller 
8051 reset circuits has inspired the authors to carry out this research (literature Study). To master the method of 
determining the value of these two components, an understanding of the working principle of charging and discharging the 
capacitor through a resistance is highly required (DC voltage source). It will not only help the students of how to calculate 
the capacitor and resistor values of microcontroller reset circuits, but will also provide a basis for them to understand other 
subjects such as Electrical, Analog Electronics, Digital Electronics, Microprocessor / microcontroller. Computers and other 
electronics studies. The authors hope this paper will contribute to science, especially in helping the teacher or lecturer to 
teach and facilitate students to comprehend the working principle of charging a capacitor through a resistance of 8051 
microprocessor reset circuit. 

Main 


The figure below shows the block diagram of the reset circuits of the microprocessor 805 1 system. 


+5V +5V 



+5V +5V 



(1) Power-on Reset Circuit and (2) With Manual Reset Option 


www.CircuitsToday.com 

Figure 1: The Types of Reset Circuits of Microcontroller 8051 [2] 


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Dahlan Rp Sitompul & Poltak Sihombing 


A 8051 Microprocessor will be in a reset state if pin 9 (RESET pin) see figure 1 above gets a 5 V DC voltage 
(Active High) for at least 2 MCs (MC-Machine Cycle) 14111511191 . 

System Clock 

K ONE MACHINE CYCLE H 

STATE6 STATE1 STATE2 STATE3 STATE4 STATES STATE6 STATE1 

| P2 | PI | P2 | PI | P2 | PI | P2 | PI | P2 | PI | P2 | PI | P2 I PI | P2 | 

“jinnnnnnnnnnnnnnni 

ALE | 

www.CircuitsTodav.com 

Figure 2: MC-Machine Cycle 141 

Figure 2 above shows a machine cycle, it can be seen from the figure that a machine cycle consists of six states 
(State 1 -State 6) and each state consists of two pulses (PI and P2), each pulse (P) is a full cycle of the oscillator (clock) 141 . 
In other words, a machine cycle consists of 12 pulses of oscillator (clock); a single machine cycle is the minimum time 
required to perform an instruction of 8051 microcontroller 115111 J , several instructions require more than one machine cycle 
(2 and 4) to complete them 11611171 . In general an instruction of 8051 microcontroller requires only one machine cycle 
(12 clock pulses), but some instructions require 2 Machine Cycles and two instructions take 4 Machine Cycles 
(MUL AB and DIV AB) 1171 to finish their work [16I[1?1 . From the above discussion we can see that to put 8051 
microprocessor in a valid reset state we must connect pin 9 of the 8051 microprocessor to a 5 Volt DC voltage source for at 
least 24 oscillator cycles (P) or 2 Machine Cycles, 2 X 12 oscillator cycles [4][131 . The period of the oscillator cycle (P) 
depends on the type of crystal used in the oscillator circuits. A 12 MHz crystal is generally used, but for application in 
associated with serial data communications a 11.0592 MHz crystal should be used 1411151 . In this study we will use the 12 
MHz crystal oscillator; you can do the same calculation for a 11.0592 MHz crystal oscillator as for 12 MHz crystal 
oscillator. 

For crystal oscillator with a frequency of 12 MHz (12 x 10 6 Hz) there will be 12 million (12 X 10 6 ) pulses per 

1 6 6 

second. Thus the period (T) of one pulse is — X 10 s (seconds), therefore the period of one machine cycle is 10 

12 

1 6 

seconds (1 u sec); 12 X — X 10 seconds. As it has been mentioned before in order to enter the valid reset state, the 8051 

12 

microcontroller pin 9 (reset) has to be connected to 5 volts (Vcc) for > 2 p sec (2 Machine Cycles) 141 . This term of time > 2 
p sec (2 Machine Cycles) will be used by the author as one of the requirements for calculating the appropriate value of R 
and C of 8051 microcontroller reset circuits. 

There are two types of reset of the 8051 microprocessor, known as power on reset and manual reset see 
figure l [2][l51 . Power on reset occurs when microprocessor gets either a DC voltage of 5 Volt from a battery or other source 
of DC voltage; voltage source with a regulator that can maintain a 5 V (DC) output voltage such as the FM7805 191 . While 
the manual reset, reset will occur when the reset button is pressed [4] . 


Impact Factor (JCC): 4.9467 


Index Copernicus Value (ICY): 3.0 


The Use of Microsoft Excel to Simulate the Charging Capacitor (C) through a Resistance (R), 
and Calculating the Appropriate Value of T (RC) of 8051 Microcontroller Reset Circuit 


139 


To analyze the 805 1 microcontroller reset circuit in Figure 1 above, we can redraw it as shown in figure 3 below 
with assumption that input impedance of the 8051 microcontroller is infinite; 8051 Microcontroller does not load the reset 
circuits. 


Vcc (5V) 



Figure 3: Microprocessor 8051 Reset Circuits 

From Electricity and basic electronics course we know that the equation for charging the capacitor through a 
resistor can be written as equation 1 below [7I[8I[1SI . 


Vc = V( 1-e t/RC ) 


(i) 


And from KVL (Kircoff Voltage Law) we know that 

V=VC + VR 

and 


VC=V —VR 

If we apply the distributive law of multiplication over subtraction on equation 1 we will get 

yc=v-i/^ c 

And from equations 3 and 4 we can see that the voltage across the resistor (R) is 


VR =Ve 


t/ RC 


(5) 


We will use equation 1 and equation 5 in Microsoft Excel to depict the graph of VC and VR (Voltage on C and R 
consecutively) versus time (seconds) as shown in Figure 4 below (t = RC = 1 second, and Vcc = 5V). 

t = RC with unit of second (s) is the time taken by the capacitor (C) to charge and achieve a voltage of 63% of the 
source voltage (3.2 V) and for the resistor ( R ) to drop from Vcc to 37% (1.8 V) of the source voltage (Vcc) if the voltage 
source is 5 V 1 ' 81 . 


When 5 Volt DC voltage source has not been connected to Vcc of 8051 microcontroller system, Vcc voltage will 
be at 0 Volts so does the voltage on the capacitor and resistor (VR + VC = Vcc), the capacitor will have a total discharge 
m . However when 5 Volt DC voltage source connected to the 8051 microcontroller system, pin 40 (Vcc) will get 5 Volt 


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DC voltage and pin 20 (GND) will get Ground (0 Volt) from the power supply, the voltage on the capacitor will initially be 
at 0 volts and the voltage of the resistor will be at 5 volts (Vcc = VR + VC) and so does the voltage on pin 9 (reset) will get 
the same voltage of 5 volts; cause the system microcontroller will enter the reset state. According to equation 1 the voltage 
on the capacitor will increase slowly from 0 Volts (the speed of capacitor charging will depend on RC value) over time 
toward 5 volts and reverse voltage development will occur across the resistor as equation 5 shows; it will go down or drop 
to 0 volts from 5 Volts which will cause the microcontroller to enters the normal state (not in the reset state) when a 
threshold voltage low (1.2 V) is reached, see figure 4 below. 



Figure 4: The Graph of Voltage Across C and R Vs Time (t (R X C)=l Second) 


When the manual reset key, see figure 1 is pressed, a voltage of 5 Volts (DC) will be at the RST pin (pin 9) of the 
8051 microcontroller and will be back soon (within a period of 0.1 seconds) to a voltage of 0 volts when the key is 
released 1611141 . 



On Reset 



Figure 5: Manual Reset of 8051 Microcontroller 1141 


When entering a reset state (manual reset) the contents of the internal RAM will not be interrupted, the contents of 
the PC (program counter) is removed and filled with OOh, bank 0 register is selected as the default bank register, (SP) Stack 
Pointer will be initialized to 07h, and all ports (port 0-port 3) will be filled with OFFh [4] . In practice the 8051 voltage logic 
is in the TTL (transistor transistor logic) voltage range 1151 , threshold voltage of 8051 microcontroller is between 1.1 V to 
1.3 V 1?1 ;input voltage below that voltage is considered to be a logic 0 voltage, and voltage above that voltage is considered 
as a logic 1 voltage. Thus the microcontroller will be in the reset state when the voltage on pin 9 (reset) is still at about 1.2 
V (average of 1.1 V and 1.3 V), the voltage on the capacitor C is 3.8 V. 


Impact Factor (JCC): 4.9467 


Index Copernicus Value (ICV): 3.0 


The Use of Microsoft Excel to Simulate the Charging Capacitor (C) through a Resistance (R), 141 

and Calculating the Appropriate Value of T (RC) of 8051 Microcontroller Reset Circuit 

The author will use this threshold voltage of 1.2 V across R (3.8 V voltages on capacitor C) as the key point in 
calculating the appropriate value of the capacitor and resistor of the 8051 Microcontroller 8051 reset circuit. 

We can use equation 5 to determine the value of R and C in accordance with the requirements (the valid reset 
conditions to occur) as mentioned above; oscillator and power supply are in stable condition, and the reset pin should be 
maintained at 5 Volts for 24 clock cycles (2 p sec) period of time. Oscillator will be stable after 1 ms and the power supply 
will be stable after 10 ms [201 ; after switching the power supply voltage on. 

From equation 5 we get that 


VR 

V 


-t/RC 

= e 


(6) 


And, 


T f VR \ T f ~ t/RC \ 

Cn( ) = Rn( e ) 

V 


(7) 


Then, we can write that. 


/.//( 


VR 

V 


) 


— t 

RC 


( 8 ) 


r 

From equation 8 we can determine the value of the corresponding RC. Ln( ) will result in a negative value. 


r 

If we put VR = 1.2 V and V=5V, then Ln{ ) will be -1,427 thus equation 8 can be rearranged into 


1,427 = — 

RC 


(9) 


As discussed earlier, when the power supply is turned on reset circuit will maintain the state of the reset pin high 
(1) for some time; duration of the reset pin in a high state is determined by the value of R and C of the reset circuit. 

To guarantee the valid reset to occur [201 , the reset pin must be maintained in a high state (5 Volts) for a long enough time to 
ensure oscillator in a start-up state (1ms), the power supply to be stable (10 ms) plus a 2-Machine Cycle (2p sec) then from 
equation 9 to ensure a valid reset state to occur we choose t> 100 m S then we can opt the equation for determining the 
appropriate value of the RC as follows [?I , 

RC>\ 00ms ( ] 0 ) 

The combination of the value of R = 10 K O, and C = lOpF will give RC = 100 ms. Reset circuits of R = 8K2Q 
and C = 10 pF is widely used in various applications of microcontroller 8051 will give RC = 82 ms. 

The graph below shows the simulation results of the voltage across the resistor for various values of t (RC); 
lms, 10 ms, 20 ms, 40 ms, 80ms, and 160 ms. 


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Dahlan Rp Sitompul & Poltak Sihombing 

































































































































































































V 
















































>_ 

So 3 - 

"5 

> 

















































\ 

\ 






















■■■ VR2(V) 

\ 
















































VR3(V) 

VR4(V) 
















































































































































1 - 


























>0 









































































o 4 

L. 




5 



0 


1C 

)0 

Time ( 

m 

15 

>) 

0 


2C 

)0 




2. 


Figure 6: Graph of Voltage across R vs. Time for Some RC Values 
(1 ms, 10 ms, 20 ms, 40 ms, 80 ms, and 160 ms) [10][11] 


the 


Table 1 below is used to depict the graphs in Figure 6. The formula for VR1, VR2, VR3, VR4, VR5, and VR6 are 

-t/lms T ^ _ —t/lOms - _ —t / 20ms -t /40ms 

following consecutively. VR\ — 5e VR2 — 5e VR3 — 5e VR4 — 5e 


VR5 = 5e 


—t I80ms 


, and 


VR6 = 5e 


—t /160ms 


Table 1: Voltage across R VS Time for Various Values of RC (1ms, 10 ms, 20 ms, 40 ms, 80 ms, Dan 160 ms) [1#I[111 


t (ms) 

VR1 (V) 

VR2(V) 

VR3(V) 

VR4(V) 

VR5(V) 

VR6(V) 

0 

5 

5 

5 

5 

5 

5 

1 

1,839397 

4,524187 

4,756147 

4,87655 

4,937889 

4,968847 

2 

0,676676 

4,093654 

4,524187 

4,756147 

4,87655 

4,937889 

3 

0,248935 

3,704091 

4,30354 

4,638717 

4,815972 

4,907123 

4 

0,091578 

3,3516 

4,093654 

4,524187 

4,756147 

4,87655 

5 

0,03369 

3,032653 

3,894004 

4,412485 

4,697065 

4,846166 

6 

0,012394 

2,744058 

3,704091 

4,30354 

4,638717 

4,815972 

7 

0,004559 

2,482927 

3,52344 

4,197285 

4,581094 

4,785966 

8 

0,001677 

2,246645 

3,3516 

4,093654 

4,524187 

4,756147 

9 

0,000617 

2,032848 

3,188141 

3,992581 

4,467987 

4,726514 

10 

0,000227 

1,839397 

3,032653 

3,894004 

4,412485 

4,697065 

11 

8.35E-05 

1,664355 

2,884749 

3,797861 

4,357672 

4,6678 

12 

3.07E-05 

1,505971 

2,744058 

3,704091 

4,30354 

4,638717 

13 

l,13E-05 

1,362659 

2,610229 

3,612637 

4,25008 

4,609816 

14 

4.16E-06 

1,232985 

2,482927 

3,52344 

4,197285 

4,581094 

15 

l,53E-06 

1,115651 

2,361833 

3,436446 

4,145146 

4,552552 

16 

5.63E-07 

1,009483 

2,246645 

3,3516 

4,093654 

4,524187 

17 

2.07E-07 

0,913418 

2,137075 

3,268849 

4,042802 

4,495999 

18 

7.61E-08 

0,826494 

2,032848 

3,188141 

3,992581 

4,467987 

19 

2,8E-08 

0,747843 

1,933705 

3,109425 

3,942984 

4,440149 

20 

1.03E-08 

0,676676 

1,839397 

3,032653 

3,894004 

4,412485 

21 

3.79E-09 

0,612282 

1,749689 

2,957777 

3,845632 

4,384992 

22 

1.39E-09 

0,554016 

1,664355 

2,884749 

3,797861 

4,357672 

23 

5.13E-10 

0,501294 

1,583184 

2,813524 

3,750683 

4,330521 

24 

1.89E-10 

0,45359 

1,505971 

2,744058 

3,704091 

4,30354 

25 

6.94E-11 

0,410425 

1,432524 

2,676307 

3,658078 

4,276727 

26 

2.55E-11 

0,371368 

1,362659 

2,610229 

3,612637 

4,25008 

27 

9,4E-12 

0,336028 

1,296201 

2,545782 

3,56776 

4,2236 


Impact Factor (JCC): 4.9467 


Index Copernicus Value (ICV): 3.0 


The Use of Microsoft Excel to Simulate the Charging Capacitor (C) through a Resistance (R), 
and Calculating the Appropriate Value of T (RC) of 8051 Microcontroller Reset Circuit 


143 


Table 1: Contd., 


28 

3.46E-12 

0.30405 

1.232985 

2,482927 

3,52344 

4,197285 

29 

1.27E-12 

0.275116 

1,172851 

2,421623 

3,479672 

4,171134 

30 

4.68E-13 

0.248935 

1,115651 

2,361833 

3,436446 

4,145146 

31 

1.72E-13 

0.225246 

1,06124 

2,303519 

3,393758 

4,119319 

32 

6.33E-14 

0.203811 

1,009483 

2,246645 

3,3516 

4,093654 

33 

2,33E-14 

0.184416 

0,96025 

2,191175 

3,309966 

4,068148 

34 

8.57E-15 

0.166866 

0,913418 

2,137075 

3,268849 

4,042802 

35 

3.15E-15 

0.150987 

0,86887 

2,08431 

3,228243 

4,017613 

36 

1,16E-15 

0.136619 

0,826494 

2,032848 

3,188141 

3,992581 

37 

4,27E-16 

0.123618 

0,786186 

1,982657 

3,148537 

3,967705 

38 

1.57E-16 

0.111854 

0,747843 

1,933705 

3,109425 

3,942984 

39 

5.77E-17 

0.10121 

0,71137 

1,885962 

3,070799 

3,918418 

40 

2.12E-17 

0.091578 

0,676676 

1,839397 

3,032653 

3,894004 

41 

7,81E-18 

0.082863 

0,643675 

1,793982 

2,994981 

3,869742 

42 

2.87E-18 

0.074978 

0,612282 

1,749689 

2,957777 

3,845632 

43 

1.06E-18 

0.067843 

0,582421 

1,706489 

2,921035 

3,821672 

44 

3.89E-19 

0.061387 

0,554016 

1,664355 

2,884749 

3,797861 

45 

1.43E-19 

0.055545 

0,526996 

1,623262 

2,848914 

3,774198 

46 

5.27E-20 

0.050259 

0,501294 

1,583184 

2,813524 

3,750683 

47 

1.94E-20 

0.045476 

0,476846 

1,544095 

2,778574 

3,727314 

48 

7.13E-21 

0.041149 

0,45359 

1,505971 

2,744058 

3,704091 

49 

2.62E-21 

0.037233 

0,431468 

1,468789 

2,709971 

3,681013 

50 

9.64E-22 

0.03369 

0,410425 

1,432524 

2,676307 

3,658078 

51 

3.55E-22 

0.030484 

0,390408 

1,397155 

2,643062 

3,635286 

52 

1.31E-22 

0.027583 

0,371368 

1,362659 

2,610229 

3,612637 

53 

4.8E-23 

0.024958 

0,353256 

1,329015 

2,577804 

3,590128 

54 

1.77E-23 

0.022583 

0,336028 

1,296201 

2,545782 

3,56776 

55 

6.5E-24 

0.020434 

0,319639 

1,264198 

2,514158 

3,545531 

56 

2,39E-24 

0.018489 

0,30405 

1,232985 

2,482927 

3,52344 

57 

8.79E-25 

0.01673 

0,289222 

1,202542 

2,452083 

3,501488 

58 

3,24E-25 

0.015138 

0,275116 

1,172851 

2,421623 

3,479672 

59 

U9E-25 

0.013697 

0,261699 

1,143894 

2,391541 

3,457991 

60 

4.38E-26 

0.012394 

0,248935 

1,115651 

2,361833 

3,436446 

61 

1.61E-26 

0.011214 

0,236795 

1,088105 

2,332494 

3,415036 

62 

5.93E-27 

0.010147 

0,225246 

1,06124 

2,303519 

3,393758 

63 

2,18E-27 

0.009182 

0,214261 

1,035038 

2,274904 

3,372613 

64 

8.02E-28 

0.008308 

0,203811 

1,009483 

2,246645 

3,3516 

65 

2.95E-28 

0.007517 

0,193871 

0,984558 

2,218737 

3,330718 

66 

1.09E-28 

0.006802 

0,184416 

0,96025 

2,191175 

3,309966 

67 

3.99E-29 

0.006155 

0,175422 

0,936541 

2,163956 

3,289343 

68 

l,47E-29 

0.005569 

0,166866 

0,913418 

2,137075 

3,268849 

69 

5.4E-30 

0.005039 

0,158728 

0,890865 

2,110527 

3,248482 

70 

1.99E-30 

0.004559 

0,150987 

0,86887 

2,08431 

3,228243 

71 

7.31E-31 

0.004126 

0,143623 

0,847417 

2,058418 

3,208129 

72 

2,69E-31 

0.003733 

0,136619 

0,826494 

2,032848 

3,188141 

73 

9.9E-32 

0.003378 

0,129956 

0,806088 

2,007596 

3,168277 

74 

3.64E-32 

0.003056 

0,123618 

0,786186 

1,982657 

3,148537 

75 

1.34E-32 

0.002765 

0,117589 

0,766775 

1,958028 

3,12892 

76 

4.93E-33 

0.002502 

0,111854 

0,747843 

1,933705 

3,109425 

77 

1.81E-33 

0.002264 

0,106399 

0,729379 

1,909684 

3,090052 

78 

6.67E-34 

0.002049 

0,10121 

0,71137 

1,885962 

3,070799 

79 

2,45E-34 

0.001854 

0,096274 

0,693807 

1,862534 

3,051667 

80 

9.02E-35 

0.001677 

0,091578 

0,676676 

1,839397 

3,032653 

81 

3.32E-35 

0.001518 

0,087112 

0,659969 

1,816548 

3,013758 

82 

1.22E-35 

0.001373 

0,082863 

0,643675 

1,793982 

2,994981 


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Table 1: Contd., 


83 

4.49E-36 

0.001243 

0,078822 

0,627782 

1,771697 

2,976321 

84 

1.65E-36 

0.001124 

0,074978 

0,612282 

1,749689 

2,957777 

85 

6.08E-37 

0.001017 

0,071321 

0,597165 

1,727954 

2,939348 

86 

2.24E-37 

0.000921 

0,067843 

0,582421 

1,706489 

2,921035 

87 

8.23E-38 

0.000833 

0,064534 

0,568041 

1,68529 

2,902835 

88 

3.03E-38 

0.000754 

0,061387 

0,554016 

1,664355 

2,884749 

89 

1,1 IE-38 

0.000682 

0,058393 

0,540337 

1,64368 

2,866776 

90 

4.1E-39 

0.000617 

0,055545 

0,526996 

1,623262 

2,848914 

91 

1.51E-39 

0.000558 

0,052836 

0,513985 

1,603098 

2,831164 

92 

5.54E-40 

0.000505 

0,050259 

0,501294 

1,583184 

2,813524 

93 

2.04E-40 

0.000457 

0,047808 

0,488917 

1,563517 

2,795995 

94 

7.5E-41 

0,000414 

0,045476 

0,476846 

1,544095 

2,778574 

95 

2.76E-41 

0,000374 

0,043258 

0,465072 

1,524914 

2,761262 

96 

1.02E-41 

0,000339 

0,041149 

0,45359 

1,505971 

2,744058 

97 

3.74E-42 

0,000306 

0,039142 

0,442391 

1,487264 

2,726961 

98 

1.37E-42 

0,000277 

0,037233 

0,431468 

1,468789 

2,709971 

99 

5.06E-43 

0,000251 

0,035417 

0,420815 

1,450543 

2,693086 

100 

1.86E-43 

0,000227 

0,03369 

0,410425 

1,432524 

2,676307 

101 

6.84E-44 

0,000205 

0,032047 

0,400292 

1,414729 

2,659632 

102 

2.52E-44 

0,000186 

0,030484 

0,390408 

1,397155 

2,643062 

103 

9.26E-45 

0,000168 

0,028997 

0,380769 

1,379799 

2,626594 

104 

3.41E-45 

0,000152 

0,027583 

0,371368 

1,362659 

2,610229 

105 

1.25E-45 

0,000138 

0,026238 

0,362199 

1,345732 

2,593966 

106 

4.61E-46 

0,000125 

0,024958 

0,353256 

1,329015 

2,577804 

107 

1.7E-46 

0,000113 

0,023741 

0,344534 

1,312506 

2,561743 

108 

6.24E-47 

0,000102 

0,022583 

0,336028 

1,296201 

2,545782 

109 

2.3E-47 

9.23E-05 

0,021482 

0,327731 

1,2801 

2,529921 

110 

8.44E-48 

8.35E-05 

0,020434 

0,319639 

1,264198 

2,514158 

111 

3.11E-48 

7.56E-05 

0,019437 

0,311747 

1,248494 

2,498493 

112 

1.14E-48 

6.84E-05 

0,018489 

0,30405 

1,232985 

2,482927 

113 

4.2E-49 

6.19E-05 

0,017588 

0,296543 

1,217668 

2,467457 

114 

1.55E-49 

5.6E-05 

0,01673 

0,289222 

1,202542 

2,452083 

115 

5.69E-50 

5.07E-05 

0,015914 

0,282081 

1,187604 

2,436805 

116 

2.09E-50 

4.58E-05 

0,015138 

0,275116 

1,172851 

2,421623 

117 

7.7E-51 

4.15E-05 

0,014399 

0,268323 

1,158282 

2,406535 

118 

2.83E-51 

3.75E-05 

0,013697 

0,261699 

1,143894 

2,391541 

119 

1.04E-51 

3.4E-05 

0,013029 

0,255237 

1,129684 

2,37664 

120 

3.83E-52 

3.07E-05 

0,012394 

0,248935 

1,115651 

2,361833 

121 

1.41E-52 

2.78E-05 

0,011789 

0,242789 

1,101792 

2,347117 

122 

5.19E-53 

2.52E-05 

0,011214 

0,236795 

1,088105 

2,332494 

123 

1.91E-53 

2.28E-05 

0,010667 

0,230948 

1,074589 

2,317961 

124 

7.02E-54 

2.06E-05 

0,010147 

0,225246 

1,06124 

2,303519 

125 

2.58E-54 

1.86E-05 

0,009652 

0,219685 

1,048057 

2,289167 

126 

9.5E-55 

1.69E-05 

0,009182 

0,214261 

1,035038 

2,274904 

127 

3.5E-55 

1.53E-05 

0,008734 

0,208971 

1,02218 

2,26073 

128 

1.29E-55 

1.38E-05 

0,008308 

0,203811 

1,009483 

2,246645 

129 

4.73E-56 

1.25E-05 

0,007903 

0,198779 

0,996943 

2,232647 

130 

1.74E-56 

1.13E-05 

0,007517 

0,193871 

0,984558 

2,218737 

131 

6.4E-57 

1.02E-05 

0,007151 

0,189084 

0,972328 

2,204913 

132 

2.36E-57 

9.25E-06 

0,006802 

0,184416 

0,96025 

2,191175 

133 

8.67E-58 

8.37E-06 

0,00647 

0,179863 

0,948321 

2,177523 

134 

3.19E-58 

7.58E-06 

0,006155 

0,175422 

0,936541 

2,163956 

135 

U7E-58 

6.85E-06 

0,005854 

0,171091 

0,924907 

2,150473 

136 

4.31E-59 

6.2E-06 

0,005569 

0,166866 

0,913418 

2,137075 

137 

1.59E-59 

5.61E-06 

0,005297 

0,162746 

0,902071 

2,12376 


Impact Factor (JCC): 4.9467 


Index Copernicus Value (ICY): 3.0 




The Use of Microsoft Excel to Simulate the Charging Capacitor (C) through a Resistance (R), 
and Calculating the Appropriate Value of T (RC) of 8051 Microcontroller Reset Circuit 


145 


Table 1: Contd., 


138 

5.84E-60 

5.08E-06 

0,005039 

0,158728 

0,890865 

2,110527 

139 

2,15E-60 

4,59E-06 

0,004793 

0,154809 

0,879799 

2,097378 

140 

7.9E-61 

4,16E-06 

0,004559 

0,150987 

0,86887 

2,08431 

141 

2.91E-61 

3,76E-06 

0,004337 

0,147259 

0,858076 

2,071324 

142 

1.07E-61 

3.4E-06 

0,004126 

0,143623 

0,847417 

2,058418 

143 

3.93E-62 

3.08E-06 

0,003924 

0,140077 

0,83689 

2,045593 

144 

1.45E-62 

2,79E-06 

0,003733 

0,136619 

0,826494 

2,032848 

145 

5.32E-63 

2,52E-06 

0,003551 

0,133245 

0,816228 

2,020183 

146 

1.96E-63 

2,28E-06 

0,003378 

0,129956 

0,806088 

2,007596 

147 

7.21E-64 

2,06E-06 

0,003213 

0,126747 

0,796075 

1,995088 

148 

2.65E-64 

l,87E-06 

0,003056 

0,123618 

0,786186 

1,982657 

149 

9.75E-65 

l,69E-06 

0,002907 

0,120566 

0,77642 

1,970304 

150 

3.59E-65 

l,53E-06 

0,002765 

0,117589 

0,766775 

1,958028 

151 

l,32E-65 

l,38E-06 

0,002631 

0,114685 

0,75725 

1,945829 

152 

4,86E-66 

l,25E-06 

0,002502 

0,111854 

0,747843 

1,933705 

153 

1.79E-66 

l,13E-06 

0,00238 

0,109092 

0,738553 

1,921657 

154 

6.57E-67 

l,03E-06 

0,002264 

0,106399 

0,729379 

1,909684 

155 

2,42E-67 

9.28E-07 

0,002154 

0,103772 

0,720318 

1,897786 

156 

8.89E-68 

8.39E-07 

0,002049 

0,10121 

0,71137 

1,885962 

157 

3,27E-68 

7,6E-07 

0,001949 

0,098711 

0,702534 

1,874211 

158 

1.2E-68 

6.87E-07 

0,001854 

0,096274 

0,693807 

1,862534 

159 

4.43E-69 

6.22E-07 

0,001763 

0,093897 

0,685188 

1,850929 

160 

1.63E-69 

5.63E-07 

0,001677 

0,091578 

0,676676 

1,839397 

161 

5.99E-70 

5.09E-07 

0,001596 

0,089317 

0,668271 

1,827937 

162 

2.2E-70 

4,61E-07 

0,001518 

0,087112 

0,659969 

1,816548 

163 

8,1 IE-71 

4,17E-07 

0,001444 

0,084961 

0,651771 

1,80523 

164 

2,98E-71 

3,77E-07 

0,001373 

0,082863 

0,643675 

1,793982 

165 

1.1E-71 

3,41E-07 

0,001306 

0,080817 

0,635679 

1,782805 

166 

4,04E-72 

3,09E-07 

0,001243 

0,078822 

0,627782 

1,771697 

167 

1.49E-72 

2,79E-07 

0,001182 

0,076876 

0,619984 

1,760659 

168 

5.46E-73 

2,53E-07 

0,001124 

0,074978 

0,612282 

1,749689 

169 

2,01E-73 

2,29E-07 

0,00107 

0,073127 

0,604676 

1,738787 

170 

7,39E-74 

2,07E-07 

0,001017 

0,071321 

0,597165 

1,727954 

171 

2,72E-74 

l,87E-07 

0,000968 

0,06956 

0,589747 

1,717188 

172 

IE-74 

l,69E-07 

0,000921 

0,067843 

0,582421 

1,706489 

173 

3.68E-75 

l,53E-07 

0,000876 

0,066168 

0,575186 

1,695856 

174 

l,35E-75 

l,39E-07 

0,000833 

0,064534 

0,568041 

1,68529 

175 

4,98E-76 

l,26E-07 

0,000792 

0,062941 

0,560984 

1,67479 

176 

1.83E-76 

l,14E-07 

0,000754 

0,061387 

0,554016 

1,664355 

177 

6.74E-77 

l,03E-07 

0,000717 

0,059871 

0,547134 

1,653986 

178 

2,48E-77 

9,3E-08 

0,000682 

0,058393 

0,540337 

1,64368 

179 

9,13E-78 

8.42E-08 

0,000649 

0,056951 

0,533625 

1,633439 

180 

3,36E-78 

7,61E-08 

0,000617 

0,055545 

0,526996 

1,623262 

181 

l,24E-78 

6.89E-08 

0,000587 

0,054174 

0,52045 

1,613149 

182 

4.54E-79 

6.23E-08 

0,000558 

0,052836 

0,513985 

1,603098 

183 

l,67E-79 

5.64E-08 

0,000531 

0,051531 

0,5076 

1,59311 

184 

6,15E-80 

5,lE-08 

0,000505 

0,050259 

0,501294 

1,583184 

185 

2,26E-80 

4,62E-08 

0,000481 

0,049018 

0,495067 

1,57332 

186 

8.32E-81 

4,18E-08 

0,000457 

0,047808 

0,488917 

1,563517 

187 

3.06E-81 

3,78E-08 

0,000435 

0,046628 

0,482844 

1,553776 

188 

1, 13E-8 1 

3,42E-08 

0,000414 

0,045476 

0,476846 

1,544095 

189 

4,14E-82 

3.1E-08 

0,000393 

0,044354 

0,470922 

1,534474 

190 

1.52E-82 

2,8E-08 

0,000374 

0,043258 

0,465072 

1,524914 

191 

5.61E-83 

2,53E-08 

0,000356 

0,04219 

0,459295 

1,515413 

192 

2,06E-83 

2,29E-08 

0,000339 

0,041149 

0,45359 

1,505971 


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146 


Dahlan Rp Sitompul & Poltak Sihombing 


Table 1: Contd., 


193 

7.59E-84 

2.08E-08 

0,000322 

0,040133 

0,447955 

1,496588 

194 

2.79E-84 

1.88E-08 

0,000306 

0,039142 

0,442391 

1,487264 

195 

1.03E-84 

1.7E-08 

0,000291 

0,038175 

0,436895 

1,477997 

196 

3.78E-85 

1.54E-08 

0,000277 

0,037233 

0,431468 

1,468789 

197 

1.39E-85 

1.39E-08 

0,000264 

0,036314 

0,426108 

1,459637 

198 

5.11E-86 

1.26E-08 

0,000251 

0,035417 

0,420815 

1,450543 

199 

1.88E-86 

1.14E-08 

0,000239 

0,034543 

0,415588 

1,441505 

200 

6.92E-87 

1.03E-08 

0,000227 

0,03369 

0,410425 

1,432524 

201 

2.55E-87 

9.33E-09 

0,000216 

0,032858 

0,405327 

1,423599 

202 

9.36E-88 

8.44E-09 

0,000205 

0,032047 

0,400292 

1,414729 

203 

3.45E-88 

7.63E-09 

0,000195 

0,031255 

0,395319 

1,405914 

204 

1.27E-88 

6.91E-09 

0,000186 

0,030484 

0,390408 

1,397155 

205 

4.66E-89 

6.25E-09 

0,000177 

0,029731 

0,385559 

1,38845 

206 

1.72E-89 

5.66E-09 

0,000168 

0,028997 

0,380769 

1,379799 

207 

6.31E-90 

5.12E-09 

0,00016 

0,028281 

0,376039 

1,371202 

208 

2.32E-90 

4.63E-09 

0,000152 

0,027583 

0,371368 

1,362659 

209 

8.54E-91 

4.19E-09 

0,000145 

0,026902 

0,366755 

1,354169 

210 

3.14E-91 

3.79E-09 

0,000138 

0,026238 

0,362199 

1,345732 

211 

1.16E-91 

3.43E-09 

0,000131 

0,02559 

0,357699 

1,337347 

212 

4.25E-92 

3.1E-09 

0,000125 

0,024958 

0,353256 

1,329015 

213 

1.56E-92 

2.81E-09 

0,000119 

0,024342 

0,348868 

1,320734 

214 

5.75E-93 

2.54E-09 

0,000113 

0,023741 

0,344534 

1,312506 

215 

2.12E-93 

2.3E-09 

0,000107 

0,023155 

0,340254 

1,304328 

216 

7.79E-94 

2.08E-09 

0,000102 

0,022583 

0,336028 

1,296201 

217 

2.86E-94 

1.88E-09 

9.7E-05 

0,022025 

0,331853 

1,288125 

218 

1.05E-94 

1.7E-09 

9.23E-05 

0,021482 

0,327731 

1,2801 

219 

3.88E-95 

1.54E-09 

8.78E-05 

0,020951 

0,32366 

1,272124 

220 

1.43E-95 

1.39E-09 

8.35E-05 

0,020434 

0,319639 

1,264198 

221 

5.25E-96 

1.26E-09 

7.94E-05 

0,019929 

0,315669 

1,256321 

222 

1.93E-96 

1.14E-09 

7.56E-05 

0,019437 

0,311747 

1,248494 


From the discussion, table 1 and figure 6 above several points can be drawn as conclusions, such as, 


• The value of RC is made in such a way as to make sure to obtain the valid duration of reset (reset pin is 
maintained in a high state for 2 machine cycles or 24 clock cycles (2 p seconds), waiting for the oscillator to 
stabilize ini ms and for the power supply to be stable in 10 ms) 


• RC value of 1 ms is too short, and will lead to failure to achieve a valid reset state; voltage VR = 1.2 is reached 
(reset occurs) in just 1.427 ms 


• For RC = 80 ms reset (VR = 1.2 V) will be reached in about 1 15 ms 


• For RC = 160 ms reset (VR = 1.2 V) will be accomplished in about 222 ms; too long 

• Equation 10 is good enough to determine the value of RC, it can guarantee the achievement of a valid reset state 
of 805 1 microcontroller 


CONCLUSIONS 


This paper is expected to contribute to science, particularly in the areas of Microprocessor, Computer, Analog 
Electronics, and Digital Electronics. And it can be used as a media for teaching and learning process that will make it 
easier for student to comprehend the subject and the teacher or lecturer to carry out the teaching process better. 


Impact Factor (JCC): 4.9467 


Index Copernicus Value (ICY): 3.0 




The Use of Microsoft Excel to Simulate the Charging Capacitor (C) through a Resistance (R), 
and Calculating the Appropriate Value of T (RC) of 8051 Microcontroller Reset Circuit 


147 


REFERENCES 

1. http://ilmukomputer.org/wp-content/uploads/2012/04/dahlan-excel-P.Teg-20121.pdf 

2. http://www.circuitstoday.com/wp-content/uploads/201 1/12/805 l-reset-circuit.jpg 

3. http://www. 805 lprojects.net/t 17721 -pO/proiect-help/proiect-help-needed.htm#post 17739 

4. http://www.circuitstodav.com/8051-microcontroller 

5. http://www.atmel.com/Images/doc4284.pdf 

6. http://www.pirc.com/tech/8051/board5/reset and crystal.html 

7. http://hillside.net/europlop/HillsideEurope/Papers/EuroPLoP1999/1999 Pont DesigningAndImplementing.pdf 

8. http://www.nhu.edu.tw/~chun/BE-Chl l-Capacitor%20Charging%20&%20Discharging. pdf 

9. http://www.circuitstodav.com/wp-content/uploads/2009/03/5v-power-supply-with-over-voltage-protection.ipg 

10. http://office.microsoft.com/en-us/excel-help/modeling-exponential-growth-HA001 1 1 1888.aspx 

11. http://www.ehow.com/how 4486593 use-excels-exp-function.html 

12. http://grok.lsu.edu/article.aspx?articleid=7094 

13. http://www.mikroe.com/chapters/view/65/chapter-2-8051-microcontroller-architecture/ 

14. http://www.mikroe.com/img/publication/8051-books/programming-8051-mcu/chapter/ch2/52.gif 

15. http://www.freewebs.com/maheshwankhede/basic.html 

16. http://www.8052.com/tuttimng.phtml 

17. http://atech-adda.blogspot.com/201 1/02/instruction-set-and-machine-cycle.html 

18. http://www.electronics-tutorials.ws/rc/rc 1 .html 

19. http://www.atmel.com/Images/doc4284.pdf 

20. http://www.8051proiects.net/download-r215-span-classsearchhighlightintelspan-mcs-51- 
classsearchhighlight8051span-user-classsearchhighlightmanualspan.html 

(Intel 8051 manual) page 200/334 


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