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Once you have a track and a kart to race on it, what’s missing? A lap counter that can give your lap times in hardcopy, obviously! That’s what led [the_anykey] to create the Arduino-based Lap Timer to help him and his kids trim those precious seconds off their runs, complete with thermal printer for the results.

The hardware uses an infrared break-beam sensor module (a Velleman PEM10D) to detect when a kart passes by. This module is similar to a scaled-up IR reflective object sensor; it combines an IR emitter and receiver on one end, and is pointed at a reflector placed across the track, up to 10 meters away. When a kart breaks the beam, the module reports the event to the rest of the hardware. Only needing electronics on one side allows the unit to be self-contained.

An obvious shortcoming of this system is the inability to differentiate between multiple karts, but for timing a single driver’s performance it does the trick. What’s great about this project is it showcases how accessible hardware is today; a device like this is possible to put together with what are essentially off-the-shelf components available to any hobbyist, using an Arduino as the glue to hold it together. We’d only comment that a red-tinted piece of plastic as an overlay for the red display (and a grey-tinted one for the green) would make the LED displays much easier to read. Still, this is a very clean and well-documented build. See it in action in the video embedded below.

If race timing that can handle multiple vehicles is more your speed, we’ve previously seen DIY lap counters intended for drone racing.


Filed under: Arduino Hacks

Beehive connected to internet.Learn how to pull realtime sensor data from a beehive to monitor its weight, temperature, and humidity over the internet.

Read more on MAKE

The post The Internet of Bees: Adding Sensors to Monitor Hive Health appeared first on Make: DIY Projects, How-Tos, Electronics, Crafts and Ideas for Makers.

Apr
16

Arduino Vs. Arduino: The Reseller’s Conundrum

arduino, arduino hacks, Arduino vs arduino, Licensing, News, sparkfun, trademark Commenti disabilitati su Arduino Vs. Arduino: The Reseller’s Conundrum 

Over the last few months, the internal struggles between the various founders of Arduino have come to a head. This began last November when Arduino SRL (the Italian version of an LLC) sued Arduino LLC for trademark infringement in Massachusetts District court. To assuage the hearts and minds of the maker community, Arduino SRL said they were the real Arduino by virtue of being the first ones to manufacture Arduino boards. A fork of the Arduino IDE by Arduino SRL – simply an update to the version number – was a ploy to further cement their position as the true developers of Arduino.

This is a mess, but not just for two organizations fighting over a trademark. If you’re selling Arduinos in your web store, which Arduino do you side with?

[Nate] from Sparkfun is answering that question with a non-answer.

Currently, Arduino SRL is the only source of Arduino Unos. Sparkfun will continue to buy Unos from SRL, but they’re not necessarily siding with Arduino SRL; people demand blue Arduinos with Italy silkscreened on the board, and Sparkfun is more than happy to supply these.

There are, however, questions about the future of Arduino hardware. The Arduino software stack will surely be around in a year, but anyone that will be purchasing thousands of little blue boards over the next year is understandably nervous.

redboardThis isn’t the first time Sparkfun has faced a challenge in Arduino supply. In 2012, when the Arduino Uno R3 was released, all the documentation for their very popular Inventor’s Kit was obsoleted overnight. In response to these supply chain problems, Sparkfun created the RedBoard.

Sparkfun has always offered to pay royalties on the RedBoard to Arduino LLC, just as they do with the Arduino Pro and Pro Mini. Effectively, Sparkfun is on the fence, with offers to manufacture the Arduino Zero, Uno, Mega, and Due coming from the LLC.

The reason for this is consumers. If someone wants an Arduino SRL-manufactured board, they’ll buy it. If, however, a customer wants to support Arduino LLC, that option is on the table as well.

It’s not a pretty position to be in, but it does show how someone can support one Arduino over another. In a year or two, there will only be one Arduino, but until then, if you have a preference, at least Sparkfun is giving you a choice.

Credit to Sparkfun for the great Spy vs. Spy image. Why don’t you sell googly eyes?


Filed under: Arduino Hacks, news
Mar
19

SXSW Create: Sparkfun Gives Kids Awesome Badges to Hack

arduino hacks, badge, badge hacking, cons, LED matrix, sparkfun, sxsw, sxsw create, wearable hacks Commenti disabilitati su SXSW Create: Sparkfun Gives Kids Awesome Badges to Hack 

By far the most desirable booth for the crowds at SXSW Create was the Sparkfun quadrant. We call it a quadrant because they had a huge footprint approaching 1/4 the tented area, but it was well used. They brought a number of staff down to Austin in order to give away a legit electronic badge project they call BadgerHack.

sxsw-sparkfun-badgerhack-kit-thumbWe love badge hacking. LOVE IT! But South-by isn’t purely a hardware conference so the badges aren’t made of PCBs (for shame). Add to that, free entry to Create scores you a wristband but no badge.

This is the answer to that, a badge giveaway and build-off aimed at kids but cool enough to make me feel only slightly awful for accepting one when I pretty much knew they were going to run out before the final day was done.

The USB stick PCB is, as you guessed it, an Arduino compatible loaded up with an FTDI chip and an ATmega328p which they call the BadgerStick. Accompanying this is a multiplexed 8×7 LED matrix board. Solder the three pin headers and the battery holder leads, connect to the plastic badge using the supplied double-stick tape, and you have a badge that scrolls a message in LEDs.

DSC_0508What an awesome giveaway. I really like it that they didn’t cut corners here. First off, the kids will value the badge much more because they had to actually assemble it rather than just being handed a finished widget. Secondly, there is the USB to serial chip and USB footprint that means they can reprogram it without any extra equipment. And an LED matrix… come on that’s just a gateway drug to learning Wiring. Bravo Sparkfun and Atmel for going this route with your marketing bucks.

The badge activity rounded out with some hardware interfacing. There’s a 3-pin socket that attendees could plug into 4 different stations around the booth. Once done they received a coupon code for Sparkfun that scrolls whenever the badge is booted up. For some at-home fun, the writeup (linked at the top) for the BadgerHack firmware is quite good. It offers advice on changing what is displayed on the badge and outlines how to build a game of Breakout with just a bit of added hardware.


Filed under: Arduino Hacks, cons, wearable hacks
Ago
21

How to Fix Your Broken MicroView

arduino, ArduinoISP, AVR, bootloader, crowdfunding, GeekAmmo, MicroView, Problem, sparkfun, tutorial, Workthrough Commenti disabilitati su How to Fix Your Broken MicroView 

The MicroView Blink  sketch running on our fixed boardThe response by GeekAmmo and Sparkfun to the MicroView problem has been amazing, but you can fix your broken one fairly simply if you're prepared to crack the case.

Read more on MAKE

Ago
20

Are you experiencing problems with your new MicroView?

arduino, bootloader, crowdfunding, Electronics, kickstarter, Micrcontrollers, MicroView, Problems, Shipping, sparkfun Commenti disabilitati su Are you experiencing problems with your new MicroView? 

Gauges on the MicroViewIf you're having problems with your MicroView, you aren't alone, as it appears that close to 2,000 boards may have been sent out without bootloaders. We talk to Marcus Schappi about the problem.

Read more on MAKE

Ott
18

MQ-3 Alcohol Sensor, Breakout Board + Arduino

adafruit, alcohol, alcohol sensor, arduino, Gas, gas sensor, sparkfun, tutorials Commenti disabilitati su MQ-3 Alcohol Sensor, Breakout Board + Arduino 

A lot has happened since our last article was published and to celebrate the continuance of bildr we’ll be playing with the MQ-3 Alcohol Gas Sensor. Coupled with the SparkFun Gas Sensor Breakout Board, connecting the MQ-3 to your Arduino is a breeze.

The MQ-3 is a heater-driven alcohol sensor that outputs an analog signal (usually interpreted somewhere between 150 and 1023 depending on how long you let the sensor warm up), which through the use of your Arduino code and calibration, can be interpreted for whatever use you need.

Putting The Pieces Together

When attaching your MQ-3 to the SparkFun Breakout Board, it should be noted that it doesn’t matter which way the MQ-3 alcohol sensor is pressed in. Both the A pins are electronically the same as well as the B pins. The center pins on both sides are the heater element pins. Since the circuit will be running on +5V DC it doesn’t matter which way the sensor is soldered to the board. As long as you have the SparkFun logos and pin labels facing downward, so you can still see them when the sensor is flipped over, you are good to go!

Note: Again, the MQ-3 is heater-driven so be aware that the sensor will become warm and may even emit a smell at first. This is completely normal.

Calibration: If you take your time, you can find out what values equate to specific percentages or even blood alcohol concentration in the case of a breathalyzer. You will of course need to calibrate your MQ-3 based on your specific Arduino code since sensor readings will vary. Although I can’t help with your specific calibration scenario, the best advice I can give you is to use several isopropyl alcohol bottles at different percentages for your testing. Do NOT get the sensor wet with alcohol! Simply squeeze to breathe the vapors of the alcohol into the sensor and take your readings.

mq3-arduino-hookup

Code

The Arduino code for this is very simple if you just want to view the raw data.

int mq3_analogPin = A0; // connected to the output pin of MQ3 

void setup(){
  Serial.begin(9600); // open serial at 9600 bps
}

void loop()
{
  // give ample warmup time for readings to stabilize

  int mq3_value = analogRead(mq3_analogPin);
  Serial.println(mq3_value);

  delay(100); //Just here to slow down the output.
}
Unless otherwise stated, this code is released under the MIT License – Please use, change and share it.

This is a tutorial on using the MSGEQ7 Spectrum Analyser with Arduino, and chapter forty-eight of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 30/01/2013

In this article we’re going to explain how to make simple spectrum analysers with an Arduino-style board. (Analyser? Analyzer? Take your pick).

First of all, what is a spectrum analyser? Good question. Do you remember what  this is?

It’s a mixed graphic equaliser/spectrum analyser deck for a hi-fi system. The display in the middle is the spectrum analyser, and roughly-speaking it shows the strength of  different frequencies in the music being listened to – and looked pretty awesome doing it. We can recreate displays similar to this for entertainment and also as a base for creative lighting effects. By working through this tutorial you’ll have the base knowledge to recreate these yourself.

We’ll be using the MSGEQ7 “seven band graphic equaliser IC” from Mixed Signal Integration. Here’s the MSGEQ7 data sheet (.pdf).  This little IC can accept a single audio source, analyse seven frequency bands of the audio, and output a DC representation of each frequency band. This isn’t super-accurate or calibrated in any way, but it works. You can get the IC separately, for example:


and then build your own circuit around it… or like most things in the Arduino world – get a shield. In this case, a derivative of the original Bliptronics shield by Sparkfun. It’s designed to pass through stereo audio via 3.5mm audio sockets and contains two MSGEQ7s, so we can do a stereo analyser:

As usual Sparkfun have saved a few cents by not including the stackable header sockets, so you’ll need to buy and solder those in yourself. There is also space for three header pins for direct audio input (left, right and common), which are useful – so if you can add those as well.

So now you have a shield that’s ready for use. Before moving forward let’s examine how the MSGEQ7 works for us. As mentioned earlier, it analyses seven frequency bands. These are illustrated in the following graph from the data sheet:

It will return the strengths of the audio at seven points – 63 Hz, 160 Hz, 400 Hz, 1 kHz, 2.5 kHz, 6.25 kHz and 16 kHz – and as you can see there is some overlap between the bands. The strength is returned as a DC voltage – which we can then simply measure with the Arduino’s analogue input and create a display of some sort. At this point audio purists, Sheldonites and RF people might get a little cranky, so once again – this is more for visual indication than any sort of calibration device.

However as an 8-pin IC a different approach is required to get the different levels. The IC will sequentially give out the levels for each band on pin 3- e.g. 63 Hz then 160 Hz then 400 Hz then 1 kHz then 2.5 kHz then 6.25 kHz  then 16 kHz then back to 63 Hz and so on. To start this sequence we first reset the IC by pulsing the RESET pin HIGH then low. This tells the IC to start at the first band. Next, we set the STROBE pin to LOW, take the DC reading from pin 3 with analogue input, store the value in a variable (an array), then set the STROBE pin HIGH. We repeat the strobe-measure sequence six more times to get the rest of the data, then RESET the IC and start all over again. For the visual learners consider the diagram below from the data sheet:

To demonstrate this process, consider the function

readMSGEQ7()

in the following example sketch (download):

// Example 48.1 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield - basic demonstration
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(115200);
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for(band=0; band <7; band++)
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
 // display values of left channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(left[band]);
 Serial.print(" ");
 }
 Serial.println();
// display values of right channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(right[band]);
 Serial.print(" ");
 }
 Serial.println();
}

If you follow through the sketch, you can see that it reads both left- and right-channel values from the two MSGEQ7s on the shield, then stores each value in the arrays left[] and right[]. These values are then sent to the serial monitor for display – for example:

If you have a function generator, connect the output to one of the channels and GND – then adjust the frequency and amplitude to see how the values change. The following video clip is a short demonstration of this – we set the generator to 1 kHz and adjust the amplitude of the signal. To make things easier to read we only measure and display the left channel:


Keep an eye on the fourth column of data – this is the analogRead() value returned by the Arduino when reading the 1khz frequency band. You can also see the affect on the other bands around 1 kHz as we increase and decrease the frequency. However that wasn’t really visually appealing – so now we’ll create a small and large graphical version.

First we’ll use an inexpensive LCD, the I2C model from akafugu reviewed previously. To save repeating myself, also review how to create custom LCD characters from here.

With the LCD with have two rows of sixteen characters. The plan is to use the top row for the levels, the left-channel’s on … the left, and the right on the right. Each character will be a little bar graph for the level. The bottom row can be for a label. We don’t have too many pixels to work with, but it’s a compact example:

We have eight rows for each character, and the results from an analogueRead() fall between 0 and 1023. So that’s 1024 possible values spread over eight sections. Thus each row of pixels in each character will represent 128 “units of analogue read” or around 0.63 V if the Arduino is running from true 5 V (remember your AREF notes?). The sketch will again read the values from the MSGEQ7, feed them into two arrays – then display the required character in each band space  on the LCD.

Here’s the resulting sketch (download):

// Example 48.2 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield and I2C LCD from akafugu
// for akafugu I2C LCD
#include 
#include "TWILiquidCrystal.h"
LiquidCrystal lcd(50);
// create custom characters for LCD
byte level0[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111};
byte level1[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111};
byte level2[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111};
byte level3[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111};
byte level4[8] = { 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level5[8] = { 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level6[8] = { 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level7[8] = { 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(9600);
 // setup LCD and custom characters
 lcd.begin(16, 2);
 lcd.setContrast(24);
 lcd.clear();
lcd.createChar(0,level0);
 lcd.createChar(1,level1);
 lcd.createChar(2,level2);
 lcd.createChar(3,level3);
 lcd.createChar(4,level4);
 lcd.createChar(5,level5);
 lcd.createChar(6,level6);
 lcd.createChar(7,level7);
 lcd.setCursor(0,1);
 lcd.print("Left");
 lcd.setCursor(11,1);
 lcd.print("Right");
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
// display values of left channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band,0);
 if (left[band]>=895) { lcd.write(7); } else
 if (left[band]>=767) { lcd.write(6); } else
 if (left[band]>=639) { lcd.write(5); } else
 if (left[band]>=511) { lcd.write(4); } else
 if (left[band]>=383) { lcd.write(3); } else
 if (left[band]>=255) { lcd.write(2); } else
 if (left[band]>=127) { lcd.write(1); } else
 if (left[band]>=0) { lcd.write(0); }
 }
 // display values of right channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band+9,0);
 if (right[band]>=895) { lcd.write(7); } else
 if (right[band]>=767) { lcd.write(6); } else
 if (right[band]>=639) { lcd.write(5); } else
 if (right[band]>=511) { lcd.write(4); } else
 if (right[band]>=383) { lcd.write(3); } else
 if (right[band]>=255) { lcd.write(2); } else
 if (right[band]>=127) { lcd.write(1); } else
 if (right[band]>=0) { lcd.write(0); }
 }
}

If you’ve been reading through my tutorials there isn’t anything new to worry about. And now for the demo, with sound -

That would look great on the side of a Walkman, however it’s a bit small. Let’s scale it up by using a Freetronics Dot Matrix Display - you may recall these from Clock One. For some background knowledge check the review here.  Don’t forget to use a suitable power supply for the DMD – 5 V at 4 A will do nicely. The DMD contains 16 rows of 32 LEDs. This gives us twice the “resolution” to display each band level if desired. The display style is subjective, so for this example we’ll use a single column of LEDs for each frequency band, with a blank column between each one.

We use a lot of line-drawing statements to display the levels, and clear the DMD after each display. With this and the previous sketches, there could be room for efficiency – however I write these with the beginner in mind. Here’s the sketch (download):

// Example 48.3 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield with a Freetronics DMD
// for DMD
#include  // for DMD
#include  // SPI.h must be included as DMD is written by SPI (the IDE complains otherwise)
#include  
#include "SystemFont5x7.h" // keep next two lines if you want to add some text
#include "Arial_black_16.h"
DMD dmd(1, 1); // creates instance of DMD to refer to in sketch
void ScanDMD() // necessary interrupt handler for refresh scanning of DMD
{ 
 dmd.scanDisplayBySPI();
}
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 // for DMD
 //initialize TimerOne's interrupt/CPU usage used to scan and refresh the display
 Timer1.initialize( 5000 ); //period in microseconds to call ScanDMD. Anything longer than 5000 (5ms) and you can see flicker.
 Timer1.attachInterrupt( ScanDMD ); //attach the Timer1 interrupt to ScanDMD which goes to dmd.scanDisplayBySPI() 
 dmd.clearScreen( true ); //true is normal (all pixels off), false is negative (all pixels on)

 // for MSGEQ7
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 int xpos;
 readMSGEQ7();
 dmd.clearScreen( true ); 
 // display values of left channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+1;
 if (left[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (left[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (left[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (left[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (left[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (left[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (left[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (left[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }

 // display values of right channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+18;
 if (right[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (right[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (right[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (right[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (right[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (right[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (right[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (right[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }
}

… and here it is in action:

Conclusion

At this point you have the knowledge to use the MSGEQ7 ICs to create some interesting spectrum analysers for entertainment and visual appeal – now you just choose the type of display enjoy the results.

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, or join our 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.


This is a tutorial on using the MSGEQ7 Spectrum Analyser with Arduino, and chapter forty-eight of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 30/01/2013

In this article we’re going to explain how to make simple spectrum analysers with an Arduino-style board. (Analyser? Analyzer? Take your pick).

First of all, what is a spectrum analyser? Good question. Do you remember what  this is?

It’s a mixed graphic equaliser/spectrum analyser deck for a hi-fi system. The display in the middle is the spectrum analyser, and roughly-speaking it shows the strength of  different frequencies in the music being listened to – and looked pretty awesome doing it. We can recreate displays similar to this for entertainment and also as a base for creative lighting effects. By working through this tutorial you’ll have the base knowledge to recreate these yourself.

We’ll be using the MSGEQ7 “seven band graphic equaliser IC” from Mixed Signal Integration. Here’s the MSGEQ7 data sheet (.pdf).  This little IC can accept a single audio source, analyse seven frequency bands of the audio, and output a DC representation of each frequency band. This isn’t super-accurate or calibrated in any way, but it works. You can get the IC separately, for example:


and then build your own circuit around it… or like most things in the Arduino world – get a shield. In this case, a derivative of the original Bliptronics shield by Sparkfun. It’s designed to pass through stereo audio via 3.5mm audio sockets and contains two MSGEQ7s, so we can do a stereo analyser:

As usual Sparkfun have saved a few cents by not including the stackable header sockets, so you’ll need to buy and solder those in yourself. There is also space for three header pins for direct audio input (left, right and common), which are useful – so if you can add those as well.

So now you have a shield that’s ready for use. Before moving forward let’s examine how the MSGEQ7 works for us. As mentioned earlier, it analyses seven frequency bands. These are illustrated in the following graph from the data sheet:

freqresponse

It will return the strengths of the audio at seven points – 63 Hz, 160 Hz, 400 Hz, 1 kHz, 2.5 kHz, 6.25 kHz and 16 kHz – and as you can see there is some overlap between the bands. The strength is returned as a DC voltage – which we can then simply measure with the Arduino’s analogue input and create a display of some sort. At this point audio purists, Sheldonites and RF people might get a little cranky, so once again – this is more for visual indication than any sort of calibration device.

However as an 8-pin IC a different approach is required to get the different levels. The IC will sequentially give out the levels for each band on pin 3- e.g. 63 Hz then 160 Hz then 400 Hz then 1 kHz then 2.5 kHz then 6.25 kHz  then 16 kHz then back to 63 Hz and so on. To start this sequence we first reset the IC by pulsing the RESET pin HIGH then low. This tells the IC to start at the first band. Next, we set the STROBE pin to LOW, take the DC reading from pin 3 with analogue input, store the value in a variable (an array), then set the STROBE pin HIGH. We repeat the strobe-measure sequence six more times to get the rest of the data, then RESET the IC and start all over again. For the visual learners consider the diagram below from the data sheet:

strobing1

To demonstrate this process, consider the function

readMSGEQ7()

in the following example sketch:

// Example 48.1 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield - basic demonstration
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(115200);
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for(band=0; band <7; band++)
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
 // display values of left channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(left[band]);
 Serial.print(" ");
 }
 Serial.println();
// display values of right channel on serial monitor
 for (band = 0; band < 7; band++)
 {
 Serial.print(right[band]);
 Serial.print(" ");
 }
 Serial.println();
}

If you follow through the sketch, you can see that it reads both left- and right-channel values from the two MSGEQ7s on the shield, then stores each value in the arrays left[] and right[]. These values are then sent to the serial monitor for display – for example:

If you have a function generator, connect the output to one of the channels and GND – then adjust the frequency and amplitude to see how the values change. The following video clip is a short demonstration of this – we set the generator to 1 kHz and adjust the amplitude of the signal. To make things easier to read we only measure and display the left channel:


Keep an eye on the fourth column of data – this is the analogRead() value returned by the Arduino when reading the 1khz frequency band. You can also see the affect on the other bands around 1 kHz as we increase and decrease the frequency. However that wasn’t really visually appealing – so now we’ll create a small and large graphical version.

First we’ll use an inexpensive LCD, the I2C model from akafugu reviewed previously. To save repeating myself, also review how to create custom LCD characters from here.

With the LCD with have two rows of sixteen characters. The plan is to use the top row for the levels, the left-channel’s on … the left, and the right on the right. Each character will be a little bar graph for the level. The bottom row can be for a label. We don’t have too many pixels to work with, but it’s a compact example:

lcdfullon

We have eight rows for each character, and the results from an analogueRead() fall between 0 and 1023. So that’s 1024 possible values spread over eight sections. Thus each row of pixels in each character will represent 128 “units of analogue read” or around 0.63 V if the Arduino is running from true 5 V (remember your AREF notes?). The sketch will again read the values from the MSGEQ7, feed them into two arrays – then display the required character in each band space  on the LCD.

Here’s the resulting sketch:

// Example 48.2 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield and I2C LCD from akafugu
// for akafugu I2C LCD
#include "Wire.h"
#include "TWILiquidCrystal.h"
LiquidCrystal lcd(50);
// create custom characters for LCD
byte level0[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111};
byte level1[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111};
byte level2[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111};
byte level3[8] = { 0b00000, 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111};
byte level4[8] = { 0b00000, 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level5[8] = { 0b00000, 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level6[8] = { 0b00000, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
byte level7[8] = { 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111, 0b11111};
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 Serial.begin(9600);
 // setup LCD and custom characters
 lcd.begin(16, 2);
 lcd.setContrast(24);
 lcd.clear();
lcd.createChar(0,level0);
 lcd.createChar(1,level1);
 lcd.createChar(2,level2);
 lcd.createChar(3,level3);
 lcd.createChar(4,level4);
 lcd.createChar(5,level5);
 lcd.createChar(6,level6);
 lcd.createChar(7,level7);
 lcd.setCursor(0,1);
 lcd.print("Left");
 lcd.setCursor(11,1);
 lcd.print("Right");
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 readMSGEQ7();
// display values of left channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band,0);
 if (left[band]>=895) { lcd.write(7); } else
 if (left[band]>=767) { lcd.write(6); } else
 if (left[band]>=639) { lcd.write(5); } else
 if (left[band]>=511) { lcd.write(4); } else
 if (left[band]>=383) { lcd.write(3); } else
 if (left[band]>=255) { lcd.write(2); } else
 if (left[band]>=127) { lcd.write(1); } else
 if (left[band]>=0) { lcd.write(0); }
 }
 // display values of right channel on LCD
 for( band = 0; band < 7; band++ )
 {
 lcd.setCursor(band+9,0);
 if (right[band]>=895) { lcd.write(7); } else
 if (right[band]>=767) { lcd.write(6); } else
 if (right[band]>=639) { lcd.write(5); } else
 if (right[band]>=511) { lcd.write(4); } else
 if (right[band]>=383) { lcd.write(3); } else
 if (right[band]>=255) { lcd.write(2); } else
 if (right[band]>=127) { lcd.write(1); } else
 if (right[band]>=0) { lcd.write(0); }
 }
}

If you’ve been reading through my tutorials there isn’t anything new to worry about. And now for the demo, with sound -

That would look great on the side of a Walkman, however it’s a bit small. Let’s scale it up by using a Freetronics Dot Matrix Display - you may recall these from Clock One. For some background knowledge check the review here.  Don’t forget to use a suitable power supply for the DMD – 5 V at 4 A will do nicely. The DMD contains 16 rows of 32 LEDs. This gives us twice the “resolution” to display each band level if desired. The display style is subjective, so for this example we’ll use a single column of LEDs for each frequency band, with a blank column between each one.

We use a lot of line-drawing statements to display the levels, and clear the DMD after each display. With this and the previous sketches, there could be room for efficiency – however I write these with the beginner in mind. Here’s the sketch:

// Example 48.3 - tronixstuff.com/tutorials > chapter 48 - 30 Jan 2013 
// MSGEQ7 spectrum analyser shield with a Freetronics DMD
// for DMD
#include "DMD.h" // for DMD
#include "SPI.h" // SPI.h must be included as DMD is written by SPI (the IDE complains otherwise)
#include "TimerOne.h"
#include "SystemFont5x7.h" // keep next two lines if you want to add some text
#include "Arial_black_16.h"
DMD dmd(1, 1); // creates instance of DMD to refer to in sketch
void ScanDMD() // necessary interrupt handler for refresh scanning of DMD
{ 
 dmd.scanDisplayBySPI();
}
int strobe = 4; // strobe pins on digital 4
int res = 5; // reset pins on digital 5
int left[7]; // store band values in these arrays
int right[7];
int band;
void setup()
{
 // for DMD
 //initialize TimerOne's interrupt/CPU usage used to scan and refresh the display
 Timer1.initialize( 5000 ); //period in microseconds to call ScanDMD. Anything longer than 5000 (5ms) and you can see flicker.
 Timer1.attachInterrupt( ScanDMD ); //attach the Timer1 interrupt to ScanDMD which goes to dmd.scanDisplayBySPI() 
 dmd.clearScreen( true ); //true is normal (all pixels off), false is negative (all pixels on)

 // for MSGEQ7
 pinMode(res, OUTPUT); // reset
 pinMode(strobe, OUTPUT); // strobe
 digitalWrite(res,LOW); // reset low
 digitalWrite(strobe,HIGH); //pin 5 is RESET on the shield
}
void readMSGEQ7()
// Function to read 7 band equalizers
{
 digitalWrite(res, HIGH);
 digitalWrite(res, LOW);
 for( band = 0; band < 7; band++ )
 {
 digitalWrite(strobe,LOW); // strobe pin on the shield - kicks the IC up to the next band 
 delayMicroseconds(30); // 
 left[band] = analogRead(0); // store left band reading
 right[band] = analogRead(1); // ... and the right
 digitalWrite(strobe,HIGH); 
 }
}
void loop()
{
 int xpos;
 readMSGEQ7();
 dmd.clearScreen( true ); 
 // display values of left channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+1;
 if (left[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (left[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (left[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (left[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (left[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (left[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (left[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (left[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }

 // display values of right channel on DMD
 for( band = 0; band < 7; band++ )
 {
 xpos = (band*2)+18;
 if (right[band]>=895) { dmd.drawLine( xpos, 15, xpos, 1, GRAPHICS_NORMAL ); } else
 if (right[band]>=767) { dmd.drawLine( xpos, 15, xpos, 3, GRAPHICS_NORMAL ); } else
 if (right[band]>=639) { dmd.drawLine( xpos, 15, xpos, 5, GRAPHICS_NORMAL ); } else
 if (right[band]>=511) { dmd.drawLine( xpos, 15, xpos, 7, GRAPHICS_NORMAL ); } else
 if (right[band]>=383) { dmd.drawLine( xpos, 15, xpos, 9, GRAPHICS_NORMAL ); } else
 if (right[band]>=255) { dmd.drawLine( xpos, 15, xpos, 11, GRAPHICS_NORMAL ); } else
 if (right[band]>=127) { dmd.drawLine( xpos, 15, xpos, 13, GRAPHICS_NORMAL ); } else
 if (right[band]>=0) { dmd.drawLine( xpos, 15, xpos, 15, GRAPHICS_NORMAL ); }
 }
}

… and here it is in action:

Conclusion

At this point you have the knowledge to use the MSGEQ7 ICs to create some interesting spectrum analysers for entertainment and visual appeal – now you just choose the type of display enjoy the results.

LEDborder

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, or join our 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: Arduino and the MSGEQ7 Spectrum Analyzer appeared first on tronixstuff.

Set
19

Kit Review – AVR ISP Shield

arduino, AVR, avrisp, DEV-11168, dev11168, isp, kit, kit review, review, shield, sparkfun, tronixstuff Commenti disabilitati su Kit Review – AVR ISP Shield 

Introduction

In the last few weeks I needed to flash some ATmega328P microcontrollers with the Arduino bootloader. There are a few ways of doing this, and one method is to use an AVR ISP shield. It’s a simple kit to assemble and use, so let’s  have look at the process and results.

As the kit is manufactured by Sparkfun, it arrives in typical minimalist fashion:

The kit includes the following items:

That’s it – no URL to instructions or getting started guide or anything. Luckily we have a bit of knowledge behind us to understand what’s going on. The PCB has all the components as SMT including the status LEDs, so the only soldering required is the shield header pins and the six or ten-connector for the programming cable. You receive enough header pins to fit everything except for both six and ten – you can have one or the other, but not both. Having some handy I thought adding my own socket would be a good idea, however the pins are placed too closed to the group of six, nixing that idea:

Assembly

After collecting all my regular soldering tools and firing up the ‘888 it was time to get to work:

The first thing to fit were the shield headers. A simple way to do this is to break off the required lengths:

… then fit them to a matching board:

… then you place the shield on top and solder the pins. After that I used some of my own headers to fit both six and ten-pin ISP headers – it never hurts to do both, one day you might need them and not have soldering equipment at the ready. Finally the zero-insertion force (ZIF) socket goes in last. Push the lever down so it lays flat before soldering. Then you’re finished:

Operation

Now to program some raw microcontrollers. Insert the shield into your board. We used Arduino IDE v1.0.1 without modifying the original instructions from the Arduino team. Now upload the “ArduinoISP” sketch which is in the Examples menu. Once this has been successful the PLS LED will breathe. You then insert the microcontroller into the ZIF socket and gently pull the lever down. The notch on the microcontroller must be on the right-hand side when looking at the shield. Finally – check the voltage! There is a switch at the bottom-left of the shield that allows 5V or 3.3V. This only changes the Vcc so programming a 3.3V microcontroller will still involve 5V via SPI – possibly causing trouble.

Next  you need to select the target board for the microcontroller you’re programming. For example, if it’s going into a Uno – click Uno, even if you’re hosting the shield with an older board such as a Duemilanove. Next, choose the programmer type by selecting Tools > Programmer >  Arduino as ISP. Now for the magic – select Tools > Burn bootloader. The process takes around one minute, during which time the “PROG” LED on the shield will blink and flicker. It turns off once finished, and the IDE also notifies you of this. For the curious, the process is in the video below:

As you hopefully noticed earlier a cable is included which allows in-circuit programming from the shield to your existing project or prototype. However we didn’t have use for it at this time, it will come in handy when doing more advanced work later on.

Conclusion

It’s simple and it works. So if you need to flash a whole tube of raw micros with the Arduino bootloader, this is an option. In Australia you can get the kit from Little Bird Electronics. Full-sized images available on flickr. This kit was purchased without notifying the supplier.

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.




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