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Some devices are internally either in the open drain or in the open collector configuration.
So in order to create a closed path for the current the device is pulled up with a resistor to the supply.
Wiki User
∙ 13y ago
Wiki User
∙ 10y agoSome of the 8051 output signals are "open drain", these need pullup resistors to bring them to the high state.
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What is the purpose of 8051 microcontrollers?
8051 Microcontrollers were popular computer chips used in Intel computers throughout the eighties and nineties. Though technology has advanced beyond their common use, they can still often be found in engineering schools as tools used in introductory microcontroller classes.
How do you reduce 48 volts dc to 12 volts dc with resistors?
Yes. You can use a voltage divider. Say, for instance, one 1KOhm resistor in series with a 3KOhm resistor. Connect the 3k resistor to the 48 volts and connect the 1k resistor to ground. The 1k resistor will have 12 volts acress it. These resistors need to be at least 1 watt each as they are going to dissipate 0.576 watts and get warm. Now, if you attempt to pull power from the 1k resistor, note that regulation will be poor because the impedance of the load will go in parallel with the 1k resistor and change its value.
Why you use 250 Ohm resistor in series with HART protocol communication?
You need to use the 250 Ohm resistor in series with HART protocol communication because it acts as a shunt resistor.
Where you can find a variable resistor on Multisim?
possibly use a potentiometre
A 1.2 k ohms resistor is placed across an 18-V source The minimum acceptable power rating for the resistor is?
1/2 watt (In theory you could use a "0.27 Watt" resistor, however there would be no safety factory and there is no standard value resistor that size.)
In microcontroller 8051 at a time how many timers you can use?
we can use both timers ...
How do you add and subtract 16 bit numbers using 8051 microprocessor?
The 8051 is a microcontroller, not a microprocessor. To add or subtract, use the ADD or SUBB opcodes.
What is a 8051 Micro-controller?
An 8051 microcontroller is a popular 8-bit microcontroller that was first introduced by Intel in 1980. It is widely used in embedded systems due to its simple architecture, low cost, and ease of use. The 8051 microcontroller typically includes CPU, RAM, ROM, I/O ports, timers, and serial communication interfaces on a single chip.
Why you use crystal in 8051 microcontroller?
for accurate time rc oscillator is common in non time critical stuff
What is microcontroller 8051?
The 8051 is a microcontroller. It has the MCS-51 core by Intel and was designed for embedded systems in the 1980's. The name of the CMOS version is 80C51. Today the core is still used in microcontrollers from other companies like Atmel, e.g. AT89C51.
Draw the block diagram of 8051 series microcontroller?
You might want to look up an image online. You can use this to draw your own diagram and label the parts.
Why use AT89C51 but not others?
89c51 microcontroller is of the series of 8051,one of oldest yet commonly used microcontroller.89c51 have the less complex features then other microcontroller and it is also easily available and cheap in comparison of other microcontrollers.
What is the purpose of 8051 microcontrollers?
8051 Microcontrollers were popular computer chips used in Intel computers throughout the eighties and nineties. Though technology has advanced beyond their common use, they can still often be found in engineering schools as tools used in introductory microcontroller classes.
How do you interface a relay to a microprocessor type 89C51?
you cannot directly interface a relay to a microcontroller, you need a buffer circuit in between the two, you can use a NPN transistor BC 547, connect the controller pin directly to the base of the transistor (since there is an internal 10k pull up resistor inside the controller no need of any base resistor). Connect the transistors emitter to the gnd & the collector to the relay coil, the another end of the relay coil goes to the supply, check this link for complete information http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Relay-Interfacing.html
Why common cathode connection is used in seven segment display using microcontroller 8051?
The output of 8051 micro controller is active high so we must need to use the common cathode type display . it will work glow when any input is high . The anode terminals of leds's of seven segment connected to 8051's output and cathode is common and grounded . so it require common cathode because 8051 provide active high output.
What are the applications of 8051 microcontroller?
embedded systemindustrialcomputer networkingThe 8051 has been in use in a wide number of devices, mainly because it is easy to integrate into a project or build a device around. The following are the main areas of focus: i. Energy Management:Efficient metering systems help in controlling energy usage in homes and industrial applications. These metering systems are made capable by incorporating microcontrollers.ii. Touch screens:A high number of microcontroller providers incorporate touch-sensing capabilities in their designs. Portable electronics such as cell phones, media players and gaming devices are examples of microcontroller-based touch screens.iii. Automobiles: The 8051 finds wide acceptance in providing automobile solutions. They are widely used in hybrid vehicles to manage engine variants. Additionally, functions such as cruise control and anti-brake system have been made more efficient with the use of microcontrollers.iv. Medical Devices:Portable medical devices such as blood pressure and glucose monitors use microcontrollers will to display data, thus providing higher reliability in providing medical results.source : engineersgarage.com/8051-microcontroller
How do you interface 3-multiplexed 7-segment displays with 8051or5052or--53--54--55 microcontroller to display a random number from 000 to 999 with 1sec delay?
You should use a mechanism called persistance of vision for interfacing multiple seven segment displays. here is tutorial for mulplexing displays using 8051 microcontroller. http://www.shree-electronics.com/interfacing_multiple_7_segment_displays.htm
