Posts with «ic» label

Spit Out VGA with Non-Programmable Logic Chips

It’s not uncommon to bitbang a protocol with a microcontroller in a pinch. I2C is frequently crunched from scratch, same with simple serial protocols, occasionally complex systems like Ethernet, and a whole host of other communication standards. But VGA gets pretty tricky because of the timing requirements, so it’s less common to bitbang. [Sven] completely threw caution to the wind. He didn’t just bitbang VGA on an Arduino, but he went one step further and configured an array of 7400 logic chips to output a VGA signal.

[Sven]’s project is in two parts. In part one, he discusses choosing a resolution and setting up the timing signal. He proceeds to output a simple(-ish) VGA signal that can be displayed on a monitor using a single gate. At that point only a red image was displayed, but getting signal lock from the monitor is a great proof of concept and [Sven] moved on to more intricate display tricks.

With the next iteration of the project [Sven] talks about adding in more circuitry to handle things like frame counting, geometry, and color. The graphics that are displayed were planned out in a simulator first, then used to design the 7400 chip configuration for that particular graphic display. It made us chuckle that [Sven] reports his monitor managed to survive this latest project!

We don’t remember seeing non-programmable integrated circuits used for VGA generation before. But bitbanging the signal on an Arduino or from an SD card slot is a great test of your ability to calculate and implement precise timings with an embedded system. Give it a try!


Filed under: video hacks
Hack a Day 16 Oct 00:01

Tutorial – LM3915 Logarithmic Dot/Bar Display Driver IC

Introduction

This is the second of three articles that will examine the LM391x series of LED driver ICs. The first covered the LM3914, this will cover the LM3915 and the LM3916 will follow. The goal of these is to have you using the parts in a small amount of time and experiment with your driver ICs, from which point you can research further into their theory and application.

Although these parts have been around for many years, the LM3915 isn’t used that much however for the sake of completeness we’re writing the tutorial. The LM3915 offers a simple way to display a logarithmic voltage level using one or more groups of ten LEDs with a minimum of fuss. If you’re wanting to make a VU meter, you should use the LM3916 which we will cover in the final instalment of this trilogy.

Instead of having each LED represent a voltage level as with the LM3914, each LED connected to the LM3915 represents a 3 dB (decibel) change in the power level of the signal. For more on decibels, check out Wikipedia.

To display these power level changes we’ll run through a couple of examples that you can use in your own projects and hopefully give you some ideas for the future. Originally by National Semiconductor, the LM391X series is now handled by Texas Instruments.

Getting Started

You will need the LM3915 data sheet, so please download that and keep it as a reference. First – back to basics. The LM3915 controls ten LEDs. It controls the current through the LEDs with the use of only one resistor, and the LEDs can appear in a bar graph or single ‘dot’ when in use. The LM3915 contains a ten-stage voltage divider, each stage when reached will illuminate the matching LED (and those below it in level meter mode).

Let’s consider the most basic of examples (from page two of the data sheet) – a simple logarithmic display of voltage between 0 and 10V:

After building the circuit you can connect a signal to measure via pin 5, and the GND to pin 2. We’ve built the circuit exactly as above on some stripboard for demonstration purposes, with the only difference being the use of an 8.2kΩ resistor for R2:

To show this in action we use a signal of varying AC voltage – a sine wave at around 2 kHz. In the following video, you can see the comparison of the signal’s voltage against the LEDs being illuminated, and you will see the logarithmic voltage increase represented by the LEDs:

We used the bar display mode for the voltage increase, and the dot display mode for the voltage decrease. Did you notice that during the voltage decrease, the LEDs below the maximum level being displayed were dim? As the signal’s voltage was varying very quickly, the change in the LED’s location is a blur due to the speed of change. In the video below, we’ve slowed the frequency right down but kept the same maximum voltage.

Well that was a lot of fun, and gives you an idea of what is possible with the LM3915.

Displaying weaker signals

In non-theoretical situations your input signal won’t conveniently be between 0 and 10 V. For example the line level on audio equipment can vary between 1 and 3V peak to peak. For example, here’s a random DSO image from measuring the headphone output on my computer whilst playing some typical music:

Although it’s an AC signal we’ll treat it as DC for simplicity. So to display this random low DC voltage signal we’ll reduce the range of the display to 0~3V DC. This is done using  the same method as with the LM3914 – with maths and different resistors.

Consider the following formulae:

As you can see the LED current (Iled) is simple, however we’ll need to solve for R1 and R2 with the first formula to get our required Vref of 3V. For our example circuit I use 2.2kΩ for R2 which gives a value of 1.8kΩ for R1. However putting those values in the ILED formula gives a pretty low current for the LEDs, about 8.3 mA. Live and learn – so spend time experimenting with values so you can match the required Vref and ILED.

Nevertheless in this video below we have the Vref of 3V and some music in from the computer as a sample source of low-voltage DC. This is not a VU meter! Wait for the LM3916 article to do that.

Again due to the rapid rate of change of the voltage, there is the blue between the maximum level at the time and 0V.

Chaining multiple LM3915s

This is covered well in the data sheet, so read it for more on using two LM3915s. Plus there are some great example circuits in the data sheet, for example the 100W audio power meter on page 26 and the vibration meter (using a piezo) on page 18.

Conclusion

As always I hope you found this useful. Don’t forget to stay tuned for the final instalment about the LM3916. And if you made it this far – check out my new book “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – LM3915 Logarithmic Dot/Bar Display Driver IC appeared first on tronixstuff.

Tronixstuff 09 Dec 04:05
bar  display  dot  driver  electronics  example  ic  level  lm3914  lm3915  lm3916  logarithmic  ti  tronixstuff  tutorial  voltmeter  vu  

Tutorial – LM3914 Dot/Bar Display Driver IC

Introduction

This is the first of three tutorials that will examine the LM391x series of LED driver ICs. In this first tutorial we cover the LM3914, then the LM3915 and LM3916 will follow. The goal of these tutorials is to have you using the parts in a small amount of time and experiment with your driver ICs, from which point you can research further into their theory and application.

Although these parts have been around for many years, the LM3914 in particular is still quite popular. It offers a simple way to display a linear voltage level using one or more groups of ten LEDs with a minimum of fuss.

With a variety of external parts or circuitry these LEDs can then represent all sorts of data, or just blink for your amusement. We’ll run through a few example circuits that you can use in your own projects and hopefully give you some ideas for the future. Originally by National Semiconductor, the LM391X series is now handled by Texas Instruments.

Getting Started

You will need the LM3914 data sheet, so please download that and keep it as a reference. So – back to basics. The LM3914 controls ten LEDs. It controls the current through the LEDs with the use of only one resistor, and the LEDs can appear in a bar graph or single ‘dot’ when in use. The LM3914 contains a ten-stage voltage divider, each stage when reached will illuminate the matching LED (and those below it in level meter mode).

Let’s consider the most basic of examples (from page two of the data sheet) – a voltmeter with a range of 0~5V:

 

The Vled rail is also connected to the supply voltage in our example. Pin 9 controls the bar/dot display mode – with it connected to pin 3 the LEDs will operate in bar graph mode, leave it open for dot mode. The 2.2uF capacitor is required only when “leads to the LED supply are 6″ or longer”. We’ve hooked up the circuit above, and created a 0~5V DC source via a 10kΩ potentiometer with a multimeter to show the voltage – in the following video you can see the results of this circuit in action, in both dot and bar graph mode:

Customising the upper range and LED current

Well that was exciting, however what if you want a different reference voltage? That is you want your display to have a range of 0~3 V DC? And how do you control the current flow through each LED? With maths and resistors. Consider the following formulae:

As you can see the LED current (Iled) is simple, our example is 12.5/1210 which returned 10.3 mA – and in real life 12.7 mA (resistor tolerance is going to affect the value of the calculations).

Now to calculate a new Ref Out voltage – for example  we’ll shoot for a 3 V meter, and keep the same current for the LEDs. This requires solving for R2 in the equation above, which results with R2 = -R1 + 0.8R1V. Substituting the values – R2 = -1210 + 0.8 x 1210 x 3 gives a value of 1694Ω for R2. Not everyone will have the E48 resistor range, so try and get something as close as possible. We found a 1.8 kΩ for R2 and show the results in the following video:

You can of course have larger display range values, but a supply voltage of no more than 25 V will need to be equal to or greater than that value. E.g. if you want a 0~10 V display, the supply voltage must be >= 10V DC.

Creating custom ranges

Now we’ll look at how to create  a lower range limit, so you can have displays that (for example) can range from a non-zero positive value. For example, you want to display levels between 3 and 5V DC. From the previous section, you know how to set the upper limit, and setting the lower limit is simple – just apply the lower voltage to pin 4 (Rlo).

You can derive this using a resistor divider or other form of supply with a common GND. When creating such circuits, remember that the tolerance of the resistors used in the voltage dividers will have an affect on the accuracy. Some may wish to fit trimpots, which after alignment can be set permanently with a blob of glue.

Finally, for more reading on this topic – download and review the TI application note.

Chaining multiple LM3914s

Two or more LM3914s can be chained together to increase the number of LEDs used to display the levels over an expanded range. The circuitry is similar to using two independent units, except the REFout (pin 7) from the first LM3914 is fed to the REFlo (pin 4) of the second LM3914 – whose REFout is set as required for the upper range limit. Consider the following example schematic which gave a real-world range of 0~3.8V DC:

The 20~22kΩ resistor is required if you’re using dot mode (see “Dot mode carry” in page ten of the data sheet). Moving on, the circuit above results with the following:

Where to from here?

Now you can visually represent all sorts of low voltages for many purposes. There’s more example circuits and notes in the LM3914 data sheet, so have a read through and delve deeper into the operation of the LM3914. Furthermore Dave Jones from eevblog.com has made a great video whcih describes a practical application of the LM3914:

Conclusion

As always I hope you found this useful. Don’t forget to stay tuned for the second and third instalments using the LM3915 and LM3916. Full-sized images are on flickr. And if you made it this far – check out my new book “Arduino Workshop” from No Starch Press.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

The post Tutorial – LM3914 Dot/Bar Display Driver IC appeared first on tronixstuff.

Tronixstuff 13 Sep 15:13
bar  display  dot  driver  electronics  example  ic  led  level  lm3914  lm3915  lm3916  ti  tronixstuff  tutorial  voltmeter  

Arduino Mp3 Player – Arduino JukeBox

A full Arduino MP3 player using a SD card and a MP3 module based on a chip from VLSI (VS1002d, VS1003 VS1053). The player includes a small amplifier and two speakers, making it a small Jukebox in the age of Ipods. The project includes a small library for the management of the MP3 and the SD chip. A Funny Arduino project ..

via [arduino-guay]

Arduino Blog 15 Nov 16:05
ic  jukebox  mp3  mp3 player  music  vs1002d  vs1003  vs1053  

Arduino Starter Kit is here to Rock

We are eager to announce the launch of the official Arduino Starter Kit! We have been working hard together in developing a complete selection of 15 projects that will let you become a true arduino tinkerer!

But that’s more:

The new starter kit has been developed together with a series of ten video tutorials hosted by Arduino co-founder Massimo Banzi, which can be viewed at www.rs-components.com/arduino. Ideally used in conjunction with the videos, the kit provides an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It contains all of the essential components required to start programming with the Arduino Uno board, and a guidebook featuring 15 different projects, which are designed to evolve the user from beginner to professional level. Comprising a motor, servomotor and driver, the kit also offers particular benefits to users wishing to apply mechatronics to their designs.

read through for the whole components and projects list

We are aware this kit will let a lot of people step in the Arduino world: for this reason we opened a brand new category of the arduino forum. You can buy the Kit on RS Components and will soon be available on the Arduino Store and the other distributors [notify me when this happen]

 

Vertical Plotter Prototype

Nice Grasshopper-to-Arduino plotter hack from FablabTorino maker Pietro Leoni, a collabotator at Carlo Ratti Associati studio in Turin. We’d love to see code & sketches online soon, as much as a second edition of the plotter.

 

Wearable Fabric on the Arduino Store

We are happy to announce the first wearable kit on the Arduino Store . This kit has been made by Plug’n'Wear specifically for us. All fabrics in this kit are produced in Italy, and strongly related to a textile family business. If you want to get deeper into the story of this product have a look at Riccardo Marchesi presentation (still in Italian, soon to be traslated!) at World Wide Rome 2012.

Read over for Kit’s features

This kit features:

  1. 1x Circular Stretch Sensor Designed by Hannah Perner-Wilson, this circular knit stretch sensor works perfect when you need to detect tension in many projects.
  2. 2x Textile push button to make easy digital inputs in cloth, scarfs o bags.
  3. 2x Spools of Conductive thread, ready to be hooked over a sewing machine
  4. 2x Soft potentiometer kit will let you import analog data into your wearable project: this kit includes 1 meter of knitted conductive tape and a metal ring. Watch it in action (see video)
  5. 10x 1k ohm resistor
  6. 10x 10k ohm resistor
  7. 1x Textile perfboard is going to change the way you think of wearable circuits. You can sew or even solder components (SMD & through-hole) on this . It can be easily cut or sewn with a standard sewing machine. Washable. Size: 15 cm x 15 cm (6″ x 6″) / Pitch: 2.54 mm (0.1″)
  8. 1x Knitted Coated Copper Tape. Small conductive tape made of coated copper fine wire (112 micron). Flexible, easy to cut, sewable with a standard sewing machine, It can be easily welded ( The coating will melt and tape will be soldered). The surface of this tape has a good insulation thrughout its lenght. Resistance: 107 Ohm/m. Width: 9 mm (0.35″)
  9. 1x Analog Textile Press Button, working with a resistive principle (resistance goes down when you press it). It works as a bend sensor as well. By connecting more sensors together it is possible to make a matrix analog switch. Sensitive area 40mm x 40mm (1.57″x1.57″)
  10. 2x LilyPad LED Bright White A simple, very bright, 250mcd, white LED LilyPad

source: [arduino store]

Arduino and the LTC2440 24bit ADC

Have you ever wondered how to improve the resolution of analog readings of your Arduino board? If yes, this is for you.

John Beale, discussing on the Dangerous Prototypes’ forum, quickly describes how to connect a Linear’s LTC2440 ADC to an Arduino board, which will provide you with an amazing 24 bit resolution.

The ADC, which is available in a SSOP package, can be connected to the Arduino via the SPI bus. Here John provides a brief sketch and some very useful comments to make it working properly.

[Via: Dangerous Prototypes]

Arduino Blog 11 Jul 14:56
24 bit  adc  hardware  ic  ltc2440  tutorials  

Insert Coin: BoardX is an open-source, modular motherboard for prolific prototypers

In Insert Coin, we look at an exciting new tech project that requires funding before it can hit production. If you'd like to pitch a project, please send us a tip with "Insert Coin" as the subject line.
We're more than a little enamored with Arduino and its DIY microcontroller ilk. But we'll admit, there are a few limitations that the compulsive prototyper might find bothersome. Chief amongst them is the lack of modularity, Now, sure, you can easily add all sorts of sensors, ports and radios to your Uno (or Duemilanove if you're old school) but that generally requires piling shield, upon shield, upon shield, until you've got a stack of boards three-feet high. And, if you want to use an ARM chip instead of an AVR for a project? Well that's a whole other set of boards. Kevin Greene has decided to address these perceived "weaknesses" with BoardX -- a modular, open-source prototyping platform.

Continue reading Insert Coin: BoardX is an open-source, modular motherboard for prolific prototypers

Insert Coin: BoardX is an open-source, modular motherboard for prolific prototypers originally appeared on Engadget on Tue, 01 Nov 2011 13:15:00 EST. Please see our terms for use of feeds.

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