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41 Threads found on edaboard.com: Multiplexing Led
By strobing I suppose you mean... (a) flashing each led for a brief instant, (b) multiplexing the led's in rotation? An easy way to do item B is to use a 4017 IC (1-through-10 sequencer). It rotates a clock signal through 10 output pins. You probably want to light each led for a brief instant. (Item A above.) Your (...)
I doubt the led/transistor current is only 20mA because they are multiplexed. multiplexing causes PWM dimming so the peak current must be pretty high to make enough average current. As you can see from the specification for saturation, beta is not used when a transistor is used as a switch. Beta is used when a transistor is a linear amplifier with
Hello All, I am working on displaying day, date & time information on 7 segment led using 74HC595 shift registers and COMMON ANODE configuration. Please see my attached diagram. I am explaining the acrchitecture as follows: 1) The top row displays time in HH:MM:SS format. 2) The middle row displays date in DD:MM:YY format. 3) The lowest row
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Hi, on first sight it seems ok. But the display seems to be an 4 x 7- segment led display. It is in multiplexing technique. Mind that the current on the digit wires (1, 2 , 3, 4) must handle max. 8 x led current. Now it depends on the led current if the AVR can source current. Also mind that with (...)
charliplexing. Switching ON one segment at one time. NOT ALL SEGMENTS. I'm working on hardware. I dont have proteus file right now. charlieplexing is not the same as (just) multiplexing segments, its purpose is to use as few pins as possible Looks like complicated way of doing things! 'Ch
ok First of all you need to have some circuit diagram for it....another thing why do you want to use two processor PIC16F877a and PIC16F72 ..... My suggestion here will be do this project in LCD than doing in seven segment displays as multiplexing seven segment require one interrupt timer...... Good Luck
Hi, After a lot of searching, I have found some similar threads but not the solution for my problem. I have two 2.3" common anode displays and I want to multiplex them and I made some circuit but it don't work. The problem is that displays are blinking, refresh rate is 60 Hz measured few times. P-channel mosfet for high side switching is BS250 and
Are you sure of your power needs? 7-segment displays usually draw far less current than 3A at 30V, that's 90W ! Most led displays use multiplexing so only one digit at a time is actually powered up and they sequence fast enough that they all appear to be lit at the same time. Can you give more information on exactly what you are trying to achive,
Hi I wan't to control around 100 RGB led (not an led matrix) and need to obtain different colours. Now I am trying the multiplexing by switching the common anode of led using a ring counter and applying the 3 channel PWM from MCU. But for me, I cannot sacrifice the led brightness, I want maximum brightness. (...)
u need to do multiplexing.....if u want to drive the matrix with few i/o pins of microcontroller. there are many led driver IC's in the market....
One possible option is the use of a Port Expander or Shift Register. 6 Digits 7-Segment led multiplexing using a Shift Register The port pins of a PIC can only be configured as input or output, not bidirectional, however the direction of a port pin can be ch
You can see Dot Matrix 8x8 or led 16X8. This is for PIC, you can see the logic to multiplexing and shifting character.
Hey guys i know how to multiplex seven segments. i have done up to four. but now i have eight. this is i doing the front pannel of my power supply, current and voltage display that is. the ic is uln2003. So should i brake them down into four and use another uln2003 or this aggangment is good? I will be using pic16f887 and apart form this mulipl
hi can anyone help me out to solve the issue in multiplexing 7 seg led using pic 16f83.... its a 10min timer counts from 0 00 to 9 59 i got output but the numbers are fluctuating... i attached code and proteus design file....
take a look at microchip application note AN529 it explains multiplexing the led displays, to use less i/o ports than you do ... it is for an older pic 16c54, but the principles are the same with a 16f877 just read the app note and you will learn how to implement your
hey! guys i wanted to use the timer 2 of 8051 to use it as the multiplexing delay for seven segment led display. So guys if anyone of u know how can i use timer 2 of 8051 please give the pseudocode or C code or assembly code will work too. thanks
hi , any one know how to write 4 digit 7 segment led display with multiplexing approach for pic18f2480 plz guide me regrads R.Anandaraj
Hi i want to use a pic microcontroller to control an array of 50 leds. I'm using two ULN2803 ICs to control the anode and cathode of the leds but i'm having problems with my schematic because ULN2803 is a NPN transistor array and i can only sink the voltage and not supply it. Is there any PNP array IC? 66524 This i
Hi, I'm building an led display from a group of 5x7 matrices. I'm building it in stages as I have got to grips with PIC programming, shift registers, multiplexing etc. My next challenge is understanding how to power it though, and I'm having no luck finding anything to help me on the web. I will be running about 10 5x7 matrices, lighting them a
An example of multiplexing is explained at the following link. Though it is for PIC but it can quickly be adopted to 8051 knowing the concept Lab 11: multiplexing seven segment led displays :Embedded Lab
You want to show each digit at least 50 times/sec so depending on how much lines you must switch you multiply that with 50, for example if you have 8 rows and you want them to switch at a speed of 50 times/sec you have to use multiplexing of 8*50=400Hz It is a similar thing with the seven segment display, the multiplexing there is accomplished
The SAA1064 is a 32-bit led controller with an I2C bus. The led controller is a bipolar integrated circuit made in an I2L-compatible 18v process. This product is optimized to drive four 7-segment led displays with decimal point by means of multiplexing between two pairs of digits. It features an I2C-bus slave transceiver (...)
multiplexing 6 7-segment displays.... im having a problem in a delay time...could u plz me help me, plz tell me the human-eye deceiving time...i mean ,the time in which human eye cannot differentiate between two events.i need dat critical time, if any-one has source code in C.i would b greatful.:oops:
Your question is a bit like "which screws do I need to build an aeroplane?" Before deciding on a parts list, you need to decide on the method of displaying you want to use. For example, are you using static drive or multiplexing, if multiplexing, what scan rate do you propose and how bright does it have to be? Is your 8x8 matrix a single cha
hello there, i am trying to multiplex five input switches to generate one output display by led. they have possible of 32 input for five bits of data. how do i make the data selection in c code??? i am using pic16f877a and am a newbie in programming. it would be appreciated if anyone can guide me. thx.
the circuit is attached help me develop the assembly code to scroll right to left and up and down
Hi pasicr, You could use 'Charlieplexing'. But the output intensity may not be appreciable. Also you need multiplexing and with 8 uC pins you can control almost 56 leds(individually). Hi I have the same problem, I want to operate 10 leds in series at a time, and want with ful glow. I tried it but intensity is not goo
Hello , Can some one please help me with my project. I need a sample code for a text, to simulate with proteus. I've tried to do it myself but i just cant get my head round it. I am familiar with the pic 16f628 and ASM. Any help would be appriciated. please help .Thankyou
I suspect the two led of the same colour are connected in reverse. The drive polarity is then reverse to light each led of the pair individually. The overall lighting of the leds is controller at a much higher rate than you can see, making use of multiplexing and perception of vision to create the effect you see. (...)
Hello I am doing a system with 8 numbers of 7 segment digits. common cathod ,directly driven from PIC port pins. Usually for systems with 4 digits what I do is a use a 300R resistor series with MCU port pins and timing I adjust by trial and error and it used to be ok. But here what ever I do with timing I am not getting a bright display. I
I need to multiplex 16 ledS with a pic, how can i make the hardware to do that?. I need to see the 16's leds without flicking.
Direct I/O control of each individual RGB led? No multiplexing?
I think that the best solution was given by another posts and is the multiplexing. It turns the circuit more simplest and use less lines. You can group the led and the activate by an transistor for example if the mux frequancy is high you will not notest the blink. using the cpld to drive your led is an problem becouse with 5 (...)
Very long message multiplexing Dear Members, Be it alpha-numeric LCD or say 7 rows 48 colums led dot matrix,I have probably a common problem.I can scroll relatively small messages quite good.But if the number of characters increases I fall short of RAM.I thought it to be normal and I was wrong.From market,a AT89C2051 and AT93C66 combination can d
Thanks all....that was what I suspected!! Actually I'm using timer0 overflow interrupt at 32mSec for multiplexing and for other purpose as well!! If I lower down its time period other....timing factor will get disturbed, so how to cope up with this trouble. BTW, I'm using 90S2313.
Hi ! The way you use multiplexing depends on several factors: - The maximum current handled by the led - The number of leds multiplexed - The multiplexing frequency - If there is a transistor switching the leds For example, if I use 4 seven segments led displays (...)
Hi everyone. I want to make a led grid to print custom messages and graphics. Let's say it's 128x64 for now. What are the limits of how many I can multiplex on the same circuit and how do you do that? All I know so far is how to do it with 7seg displays. How do I control so many circuit paths? Multiple MCUs? For 128x64, if I was able to br
Dear ALL, Anybody having any experience handling CD4094B whose clock and strobe are shorted? I have to use such a board for led matrix multiplexing. Any idea what happens when clock and strobe tied togetherin a SIPO shift register? Best Regards. A.S.Rudra
Basically yes - but the LCD has a much slower response than an led so the multiplexing frequency cannot be very high. On the other hand a static drive is not good either because it will cause "burn-in" of the segments. Check this link for some useful information:
I need a sample program that uses moving display message using pic micro. Program can be in assembly or better picbasic pro. Thanks. :idea: