Wednesday 20 April 2016
Saturday 10 October 2015
74HC165 Shift Register and your Arduino UNO
Today in this tutorial i'll explain you how to control 74HC165 parallel in serial out(PISO) shift register using your ARDUINO board.Here we used 74HC165 for increasing numbers of inputs of your ARDUINO board.Shift registers are often used for the purpose of saving pins on a microcontroller. Every microcontroller has a limited number of pins for general inputs and outputs (GPIO).Some time we have required more inputs and our controller does not provide such a inputs at that time parallel in serial out(PISO) shift register is used to increase inputs.
An 8 bit shift register needs 4 lines of a microcontroller. One pin to clock for data transfer,one for clock enable,one for shifting/loading/latching the bits,and one for serial data transfer.Here we used only 3 pins of microcontroller. One pin for loading the bits,one pin to clock for data transfer,one pin to serial data transfer.In 74HC165 Clock enable pin is active low so we connect it to ground.Two 74HC165 can be cascaded to increase lots of inputs.
Saturday 5 September 2015
Multiplexed Seven Segment Display interfacing with 8051
We have already discuss basic about "single seven segment interface to 8051" in which seven segment is individually drive through 8 pin of microcontroller AT89S52. If we want to display two,three or more seven segment display using single MCU than there is problem that we face is lack of I/O pins in MCU, as one seven segment would take 8 I/O pin and four seven segment would take 28 I/O pins.That's why multiplexing technique is used to drive multiple seven segment display. In this tutorial i'll explain you how to interface multiple seven segment display to 8051.
Here we'll used "persistence of vision" to archive this multiplexing.This technique is used in cinematography to display images so fast that our brain cannot distinguish any lag between two consecutive images. Similarly, when we multiplex more than one seven segments, we display only one Seven segment at a time, and we switch between them so fast that our brain cannot distinguish between them.
In multiplexing all the display are connected in parallel such that if you active any segment than the particular segment of all displays glow up.But we switch on and off the common line of segment very fast.
In multiplexing all the display are connected in parallel such that if you active any segment than the particular segment of all displays glow up.But we switch on and off the common line of segment very fast.
Circuit Diagram:
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| Multiplexed Seven Segment circuit diagram |
In the above circuit all the similar segment of seven segment display are connected together and which is connected to the PORT0 of AT89S52 through current limiting resistors(R2 toR9).Particular segment is turn on when the corresponding pin of PORT0 is high(1) because segment is common cathode.But it'll not glow until it's cathode is not connected to ground.But here cathode of the seven segments are not directly connected to ground.Three NPN (BC547) transistor is used as a switch to on and off the particular segment.Therefore, the transistor selects which displays is active at a time.Here base of all three transistor are connected to the P2.0, P2.1, P2.2 through base resistor don't forgot to put base resistor may your transistor stop working.Common line of segment is connected to ground when the logic high(1) is apply to the base of the transistor and disconnected when logic low(0) is apply to the base of transistor.
Saturday 29 August 2015
Burning the Bootloader on ATMega328 using USBasp Programmer
In this tutorial you'll learn how to burn arduino bootloader on new ATmega328 using USBasp ISP programmer.Please be noted that every Arduino Board comes with a microcontroller ATmega328 pre-program with arduino bootloader firmware. Therefore, there is no need to burn the bootloader firmware again.But if you want to make your own DIY arduino board than you need to burn arduino bootloader into ATmega328.So here i'll show you how to load arduino bootloader into atmega328 step by step.
Required components:
- USBasp Programmer
- Bread Board
- ATmega328
- 2pcs 22pf Cap.
- 16MHz Crystal
- 10K Resistor
- Hook up wire
- AVRdude Software
First of all wire up the circuit in breadboard as show in below diagram.Please connect all the connection carefully.
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| ATmega328 connection with USPasp |
Show in above circuit JP1 is from USBasp programmer. Connect all the connection carefully as per above diagram using jumper wire.If you wire up your circuit correctly than it's time to load hex file which is located in your arduino software folder here is complete path arduino-1.0.5-windows\arduino1.0.5\hardware\arduino\bootloaders\optiboot\optiboot_atmega328.hex you can also download from here optiboot_atmega328
Thursday 13 August 2015
Interfacing Seven Segment Display to 8051
Hi friends in this tutorial i'll explain you how to interface single seven segment display to 8051 micro-controller.You just need to some basic knowledge of seven segment display and 8051 programming.If your are newbie to seven segment display than you can learn basic about seven segment display from my older post about seven segment display.You can learn all about seven segment display from this post.
Now we interface common anode seven segment display with AT89S52. I already describe basic about common anode display.
Circuit Diagram
Here,common anode display is used to display digit 0 to 9 and some time used to display alphabets A to F,dot is use to display decimal point.Show in circuit diagram pin a to g of seven segment is connected to the port P2 of AT89S52 microcontroller through the current limiting resistors R2 to R9(330R) and common pin is connected to the Vcc(5V).Make sure that a to g pins of 7 segment are connected to the P2.0 to P2.6 respectively.Since we are using common anode seven segment display so we need to send logic-0 to the particular segment to glow.
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| Seven segment interface circuit diagram |
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