Tagged Questions

2
votes
2answers
104 views

How can I control 8 LEDs with a timing delay with only one microcontroller (PIC12) written in Assembly?

I can have 5 I/O pins enabled. I'm just confused on how to control them individually.
0
votes
0answers
53 views

LED display has noise

I am developing a LED display driver. It uses a PIC18F452 microcontroller and a 74hc245 IC. It uses the SPI protocol to send signals to the LED display. When there are small number of LEDs switched ...
0
votes
2answers
167 views

Transistors never work for me

TOday, I have built an LED cube. I put it all together, arduino, mess of wires and all, and it doesn't work. Fiddling with it a little bit, I find that if I short certain wires to ground, the LED's ...
2
votes
1answer
174 views

how to put led to indicate the signal is functioning

I want to connect an input signal to pc817 and the output to a microcontroller. I don't know how to put the LED at the input to indicate that the input signal is working. For example my input is ...
1
vote
1answer
86 views

Maximum LEDs on a matrix

There are several methods to drive LEDs using a microcontroller. The easiest method is just connecting all LEDs to an own pin on the microcontroller. Say you have \$n\$ pins available, you'll be able ...
3
votes
2answers
159 views

Multiple micro controllers to control LED matrix

I am planning to use 5 40 pin Picaxe micro-controllers to control a 70x70 LED board matrix. My plan is to use 4 of the micro-controllers to control the LEDs and the 5th to tell the other ...
1
vote
1answer
398 views

How to drive high power LED and Arduino by the same power source?

I am building a plant light consisted of 24 high power LEDs (Cree ML-E) and an Arduino Uno. I would like to power the LEDs and the Arduino by the same power source. Since creating circuits for dealing ...
2
votes
2answers
188 views

LED tachometer with PIC MCU (requires more current)

I've been working on an LED tachometer that will be installed on an open wheel race car. After putting the order through for the PCB I re-calculated the current draw and turns out the PIC's (16F877A) ...
0
votes
1answer
102 views

Performing different actions on the same timer

I am working with MC9S08AW60 on the Board-DEMO9S08AW60E. I have written the following code to perform Serial Comm, LED sequence and Keyboard Tx-RX. ...
-3
votes
2answers
278 views

RGB LED using PWM [closed]

I am working on a RGB project using PWM. I need help in C- code. I want to display different colors from LED. But due to my small info of C- language it is difficult. Is there any guy can help me in ...
1
vote
1answer
650 views

Building a 3x3x3 LED cube?

I need to built a 3x3x3 LED cube. I need to be able to turn every LED on (not at the same time) in different patterns. I need to use Charlieplexing (note that any other method is not a viable ...
8
votes
1answer
586 views

How can I calculate a Joule Thief

A Joule Thief is a simple step-up converter with which you can drive a 3.6V LED with a 1.5V battery even if it is spending the last drops of its life. It merely consists of a transistor, a transformer ...
1
vote
2answers
199 views

Switch on a LED: why doesn't this code work?

I am using DEMO9S08AW60E and using Codewarrior(Version: 5.9) with Processor Expert. ...
2
votes
1answer
181 views

DMX512 Remote controlled LED

I'm having a problem with this circuit. I am trying to get an LED wash light circuit to be remote controlled via DMX512. The problem is, after I designed the circuit for the RS485 (which will deliver ...
2
votes
2answers
563 views

RGB LED Strip - Variable Voltage Vs. PWM

I am going to install an Analog RGB (non adressable) LED strip in my room and need to make a driver for it. The LED strip specs are: 10 cm segment 12V @ 60mA max per segment I would be using ...
1
vote
1answer
377 views

driving a LED with an open drain digital input

I need to drive a LED from an STM32F217ZG. So I was thinking putting a classid circuit with a BJT. But then I saw that GPIO output of the microcontroller are configurables in open drain. So would ...
10
votes
3answers
609 views

Attaching a LED to PIC's Rx pin

I need some way to know whether the microcontroller (PIC) is receiving (or transmitting) any data. So I thought of keeping a ...
2
votes
2answers
478 views

How do I convert 6V DC to 12V DC in a relatively small form factor.

I want to convert 6V DC from batteries to 12 V DC to drive 1m of LED strip (60 LEDs per meter) whilst using the 6 V to power a microcontroller 4 TPIC5C569 Shift Register 1 SD Card 32 LEDs Also, the ...
5
votes
1answer
469 views

Led Matrix using PIC

For a project I am working on, I want to build a 9x9 monocolor LED matrix also with 9 push buttons to control the LEDs using the PIC. So far I have gathered that I think I will be needing shift ...
0
votes
0answers
252 views

Atmel microcontroller LED circuit build [closed]

so now I'm building this is a follow on from my previous posts. If this is first time reading. I am trying to do- press switch for activation first light comes on pre programmed in 1.5secs then ...
3
votes
3answers
293 views

microcontroller programming

In reference to this question Is it possible to program the LEDs each to flash on consecutively each with its own activation speed in the sequence chase then add some sort of a randomizer ...
3
votes
1answer
243 views

LED randomizer microcontroller SFF (Small Form Factor) circuit

I want 12 leds in the circuit programmed to go around at a certain speed. 17 smd leds in total. What I need to do is for the chase to randomly chose to slow down for 1 second or speed up for 1 second ...
1
vote
2answers
2k views

Designing high-power LED driver with PWM

Update: Provided I set up the PIC and program it correctly (planning on using this guide to interface it as a USB HID device), would this be a suitable configuration? I'm not entirely certain how I ...
5
votes
2answers
448 views

How can I use one microcontroller to increment/decrement 4 sets of LEDs using 8 push button inputs?

I want to design a very small project for a portable score keeper. It consists of using one microcontroller to control 4 sets/groups of LEDs on a small PCB. It is a very small scale project (3.5in X ...
2
votes
1answer
123 views

Patterns for a strip of leds

I am working on how to get a strip of 60 leds to generate a pattern or how to get at least a running light with 8 on leds. So I have two questions a) Can they it be done without the help of Arduino or ...
1
vote
2answers
277 views

Is is possible to communicate over 1 XBee to multiple microcontrollers?

MC1>XB1 ==> XB2>MC2,MC3,MCn What I am looking to do is control large LED panels, wirelessly, with control of each LED pixel. My concern is the processing limitations of a single controller and/or the ...
3
votes
3answers
607 views

How to flash LEDs with a microcontroller?

What I'm planning to do is program a microcontroller to keep track of time and flash LED lights. The features I would need: Decrease/increase interval between flashes Flash specific LED lights ...
10
votes
3answers
467 views

Possible causes for 7-segment LED flicker

I'm working with a vendor overseas to revamp an existing product. We're trying to keep cost down. Currently the product consists of: 4 large buttons 4 double digit 7-segment LEDs. (each button has ...
1
vote
3answers
524 views

Want to control 30V LED strip with a microcontroller, any help or ideas?

Like the title says i want to control around 30volts of current (multiple LEDs that will be running all at once, added up to about 30volts.) i want to use a micro-controller to control it so i can add ...
3
votes
3answers
543 views

3 RGB-LED with only 3 resistors

I have 3 RGB LEDs with common anode, a shift register and a microcontroller. Currently I have connected a series resistor for each cathode of the RGB LED, so there are 9 resistors in sum. I wondered ...
1
vote
2answers
597 views

Simple solution for driving a large-ish RGB LED array with PWM

I'm working on a small toy-like device that has a 10 x 8 "pixel" array of RGB LEDs at its core; thus there are 10 x 8 x 3 = 240 individual LEDs to be controlled. I'd like to control the intensity of ...
1
vote
1answer
184 views

LED before input to Micocontroller

I am designing a circuit to provide a logic high (5V) or logic low (0V) to a microcontroller. How can I incorporate an LED into the circuit so that it is on/off when the logic is high/low, while still ...
8
votes
1answer
1k views

Drawing on 8x32 LED matrix with 74HC154

How do I send a pattern into an 8x32 LED matrix? I'm using the AT89S52 microcontroller with a 74HC154 4-16 line decoder, programming in C with the Keil IDE. I've done vertical scanning, but am stumped ...
-2
votes
1answer
3k views

how to make a propeller clock using a micro controller?? [closed]

I would like others to explain, how to make a propeller clock, which is responding to human voice.
2
votes
4answers
621 views

14 volts and PWM with Atmega8

I wanted to control the LEDs on my model railroad with a microcontroller and (maybe Soft-)PWM, but just saw, that most of the LED stuff you can buy for model railroads runs at 12-16V and also the ...
2
votes
2answers
605 views

I want to build an interactive LED Table. What are my options for a controller?

I have seen a couple of videos and instructables where people have created a matrix of LEDs controlled by photodiodes/photoresistors inside coffee tables, so that when you put your hand over the table ...
2
votes
1answer
248 views

need help “hacking” LED display

The display is a scrolling LED sign which looks like this: It is also distributed in the US by Grandwell (SLC16H-IR). The messaging software that it comes with does not allow full control of the ...
2
votes
1answer
403 views

Voltage controlled voltage source

I am designing a high powered LED driver controlled by a microcontroller. Now it would be very easy to make a constant current limiter so I don't burn out my LED. I have a bunch of LM317's and ...
4
votes
2answers
546 views

Building a simple mcu-driven array of LEDs

I'm planning to put together a simple shift-register driven array of LEDs as a first project, something akin to this: But using a 74HC595 shift register (two, eventually) and a transistor to drive ...
6
votes
5answers
5k views

How can I control many LED's with just a few pins on my micro?

I am using an Atmel ATTINY13 which has a 6-pin I/O. I'd like to control about 15 LED's but am unsure how to connect everything. Without multiplexing of any sort, it seems I'd only be able to control 6 ...
2
votes
1answer
482 views

How to switch/power a 13x13 LED Matrix?

Hey all - I have an AVR project in mind that will require a 13 by 13 LED matrix of bright white LEDs. I'll be wiring up my own matrix to do this (not using premade 8x8's). I plan on using some shift ...
7
votes
3answers
4k views

How to pick a switching transistor to drive LEDs? Or, how to read a transistor data sheet?

I'm going to be driving a bank of 20-25 LEDs from a single output of a PIC micro. Obviously, I need a transistor, because that's going to be somewhere in the vicinity of 400 mA (the LEDs are speced at ...
7
votes
9answers
1k views

Serial control of 25 LEDs from a single pin

I have a microcontroller with one available digital pin. How can I control 25 LEDs?
1
vote
1answer
546 views

Problems driving leds with the MM5450

First what is my final goal: to drive 24 RGB LEDS using a microcontroller connected serially to a Micrel MM5450 LED driver. It would be nice to be able to drive all of them individually (72 LEDs), but ...
4
votes
2answers
997 views

LED Driver for 300mA LEDs

I'm trying to put together a project with some bright LEDs but I'm not sure how to control them. Ideally I'd like to drive about 64 of these LEDs that have a forward current of 300mA and voltage drop ...
3
votes
2answers
1k views

How much current can a microcontroller/DSP pin sink/source?

I'm using a TMS320F2812 and want to drive LEDs of some of the pins. I couldn't figure out what the safe levels of current were which could go in or come out of the IO pins from the datasheet. What is ...
15
votes
10answers
3k views

I'd like to learn how to make my own USB gadgets

I've been writing Linux character device drivers for other people's stuff for some time. I'd like to find a new hobby and the thought of making my own USB gizmos seems really neat. I would be ...