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Generally the output pin of the MCU will be, between 4.3V and 5V when high and will allow a maximum current of 15mA, an LED will have a volt drop of about 2 volt in forward bias conditions at 10mA which is about the minimum current to make it glow normally.
Place a resistor in series with the MCU pin and the LED, connect the cathode pin of the LED to the ground. As an on state is created on the MCU, the current will flow through the resistor to the LED, through the anode, flow through the LED to the ground
The minimum current for LED at the minimum voltage is must be used to obtain the Rs
Rs=(Vmcumin-Vled)/Imin
Rs=(4.3V-2V)/0.01A
= 230R using a higer value 330R should be fine
Imcu = (5V- 2V) / 330R = 9.1mA it should be safe for your MCU and it should produce a visible indication.
I will not recommend making it to bright, LEDs can easily go to about 20mA but for most applications around 10mA is enough
If one would need to use 15mA or more, then the help of an external transistor is recommended. Then you have VCC going through resistor Rs through LED Anode to Cathode to the collector of a NPN BJT transistor. Then from the Emitter to the ground. From the MCU let the voltage go though resistor Ri to the Base of the transistor. Generally it is bad to switch loads this way, since the loads are never properly grounded and said to be floating, but for LED it is ideal.
Then
Rs = (VCC-Vled-Vce) / Iled = (5V-2V-0.2V)/0.01A = 280R NAV = 330R
Ic = (Vcc-Vled-Vce)/Rs = (5V-2V-0.2V)/330R = 8.47mA
then
ib = Ic/Beta = 8.47/100 = 84.8uA
to allow some tolerance let Ibnew = Ib x 10 = 848uA
Ri = (Vmcumin - Vbe)/Ibnew = (4.3V-0.7V)/848uA = 4.245K NAV = 4k7
The transistor:
Ie= (Vmcumax-Vbe)/Ri = (5V-0.7V)/4.7k = 915uA
Power dissipation for transistor is
Pd= Vce x Ie = 0.2V x (Ib + Ic) =0.2 x 0.009395 = 1.88mW
one can see, a very small transistor is required.
What else can I help you with?
How do you write the 8051 micro controller alp for finding the largest number in an array?
1
How do you connect potentiometer with 8051?
The simplest way would be via an ADC
Advantages of pic controller over 8051?
Well, honey, a PIC controller typically has a faster execution speed and lower power consumption compared to an 8051. Plus, PIC controllers often have a larger variety of peripherals and are more cost-effective for certain applications. But hey, at the end of the day, it all depends on what you need for your project, so pick your poison wisely.
Difference between 8031 8051 and 8751 microcontrollers?
Answer It is both 8 bit processors in a 40 pin package but it is not pin compatible, it have almost the same functions but it is very difficult to compare the two because it is not the same family.
Is 8051 programming is a programming language?
8051 programming refers to the Intel 8051 micro-controller. This is a small computer on a single chip having electronic input output that is used to control simple machinery.The 8051 uses an instruction set consisting of binary codes and data that may be used to describe the algorithms that the microprocessor runs. These instructions are published by Intel with a set of mnemonic words that are designed to enable the programmer to remember the instructions. These mnemonics are not part of a formal programming language because they have no syntax apart from the instruction and data values for each command that the processor might execute.The instructions could be placed in any order such that no particular algorithm is expressed.A formal programming language however requires structure and syntax that describes the algorithm as an abstract concept apart from the system that might run the program. A programming language, such as C, C# or Java will be portable across machines but 8051 assembly code will only run on that processor.In short then, the 8051 assembly code is not a programming language as such.
How temperature is measured using 8051 micro-controller?
how temperature is measured using 8051 micro-controler?
What are 8051 based systems?
The 8051 is a micro-controller series, basically a computer on a chip. A system based on the 8051 series micro-controller is simply that, a device or series of devices that operate under control of one or more 8051 micro-controllers.
Difference between avr micro controller and 8051 micro controller?
constructed on a single chip is called micro processor constructed on a single board is called micro controller
Why 8051 is called 8 bit micro controller?
A: Because it can only control 8 bits of data.
How do you write the 8051 micro controller alp for finding the largest number in an array?
1
What is purpose of ram in 8051 micro controller?
the internal RAM is for data storage and for many applications is all that is needed.
What are the advantages of PIC micro controller over 8051?
In general, personal preference and experience is what it comes down to. There are some PIC's that have built in RF systems; I don't believe there are any 8051's with this capability.
What are the advantages of PIC micro-controller over 8051?
In general, personal preference and experience is what it comes down to. There are some PIC's that have built in RF systems; I don't believe there are any 8051's with this capability.
How many ports in 8051 micro controller?
They are mainly four ports in 8051MC. port 0 port 1 port 2 port 3
Why you use 12mhz in 8051 micro controller?
Like many early microprocessors it has a 1mhz internal clock for its' operation. 12mhz is divided internally by 12 to derive this frequency.
What are the control signals for 8051 micro controller?
EA - External Access PSEN - Program store Enable ALE - Address Latch Enable RST - Reset WR - RD
How do you connect ADC 0804 with 8051 series?
8051 is old MCU technology there is other MCUs on the market with build in ADCs, the PIC MCU from Micro Chip is the most popular and is very easy to program, more about PIC at this link http://www.patenttrade.net
