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1  Using Arduino / Project Guidance / Re: Making multiple POST requests on: Today at 08:17:42 am
OK, that's the sketch where you didn't try to send a POST in loop().  What does the sketch where you DID try to send a POST in loop() look like and in what way is it not working as desired?
2  Using Arduino / Motors, Mechanics, and Power / Re: arduino micro + peltier module + h bridge + LM35 on: Today at 08:11:54 am
Don't Peltier modules draw a LOT of current?  I hope you have a very hefty 9V battery.

An Arduino will run on 3V but at 16 MHz you should not feed it less than 3.7V.  You can run at 8 MHz down to 2.4V:
3  Using Arduino / Networking, Protocols, and Devices / Re: SPI problem/SD card/DS3234 on: Today at 06:44:28 am
Hi, I have the same problem, but I don't understand very well how to resolve this problem ?

Use this library instead of the built-in SD library:
The new version of SdFat:
4  Topics / Robotics / Re: help with my arduino program! on: July 23, 2014, 08:13:27 pm
Hi, I have some doubts with the arduino program.
My objective is to control 5 servo motors with one button each.

Use arrays, like this:
#include <Servo.h>

const int ButtonCount = 5;

const int servoPins[ButtonCount] = {
const int buttonPins[ButtonCount] = {

int buttonStates[ButtonCount];    //Variable para leer el estado del pulsador
int directionStates[ButtonCount]; //Variable para leer la dirección del servo 1

Servo myservos[ButtonCount]; //Crear el objeto servo para controlar el servo

int positions[ButtonCount];   //Variable para almacenar la posición del servo

void setup() {
  for (int i=0; i<ButtonCount; i++) {
    myservos[i].attach(servoPins[i]);         //Conectar servo al pin 3
    pinMode(buttonPins[i], INPUT); //Iniciar pin del boton como entrada

void loop() {
  for (int i=0; i<ButtonCount; i++) {
    //lee el estado del valor del boton
    buttonStates[i] = digitalRead(buttonPins[i]);

    if (directionStates[i] == 0) {
      //boton presionado
      if(buttonStates[i] == HIGH) {
        directionStates[i] = 1;    //la direccion del servo es a la derecha

        //va desde 0 grados a 180 grados en pasos de 1 grado
        for(positions[i] = 0; positions[i] < 180; positions[i]++) {
          myservos[i].write(positions[i]);  //Dice al servo que valla a la posicion de la variable ¨pos¨
          delay(15); // espera 15ms para que el servo llegue a su posición
    else if (directionStates[i] == 1) {
      // boton presionado
      if (buttonStates[i] == HIGH) {
        directionStates[i] = 0;    // la dirección del servo es a la izquierda

        // va de 180 grados a 0 grados en pasos de 1 grado
        for(positions[i] = 180; positions[i]>=1; positions[i]--) {
          myservos[i].write(positions[i]);  //dice al servo que valla a la posición de la variable ¨pos¨
          delay(15);           //Espera 15ms para que el servo llegue a su posición
5  Using Arduino / Project Guidance / Re: Frequency Measurement of a Guitar String. on: July 23, 2014, 05:15:07 pm
Maybe average 10 readings, throwing out any data points more than 10% below the current average?

   float average = getFrequency();
   for (int i=1; i<=10; ) {
      float frequency = getFrequency();
      if (frequency < (0.9 * (average/i)))
           continue;  // Skip this sample
      average += frequency;
6  Using Arduino / LEDs and Multiplexing / Re: Can a ULN2803APG drive a 12V led strip with 440ma load? on: July 23, 2014, 03:53:19 pm
There is a chart in the datasheet showing output current vs. duty cycle with all outputs active.  I think that it is showing that you can get 440 mA out but only at about 5% duty cycle.   At 100% duty cycle the output current drops to about 60 mA. 

Perhaps some logic level power MOSFETs would handle the current better.
7  Using Arduino / Displays / Re: Reprogram Default Character Set on: July 23, 2014, 11:47:29 am
I didn't see anything in the the datasheet about restoring the character NVM (EEPROM).  I suspect you will have to find the data somewhere and upload it.

Looks like the evaluation kit includes defaultCM.mcm which contains the default character set:
8  Using Arduino / Networking, Protocols, and Devices / Re: Connecting my GPS to the Arduino on: July 23, 2014, 11:28:31 am
Some people have had problems with the serial receive buffer being too small to hold the whole message. You may want to edit this line in SoftwareSerial.h:
#define _SS_MAX_RX_BUFF 64 // RX buffer size
9  Using Arduino / Networking, Protocols, and Devices / Re: Connecting my GPS to the Arduino on: July 23, 2014, 08:39:13 am
Does the GPS have a clear view of the sky?
10  Using Arduino / Project Guidance / Re: Content length? on: July 23, 2014, 08:28:26 am
"The Content-Length entity-header field indicates the size of the entity-body, in decimal number of OCTETs, sent to the recipient or, in the case of the HEAD method, the size of the entity-body that would have been sent had the request been a GET."

Sounds like you should be counting the line endings, too.
11  Using Arduino / Project Guidance / Re: Sending data to 2 ports without delay on: July 23, 2014, 08:21:47 am
Add a 16-bit (or two 8-bit) shift registers.  Shift the data out and then latch all 16 bits in the output register simultaneously.

If you use the SPI interface you can shift data out at 8 megabits per second.
12  Using Arduino / Installation & Troubleshooting / Re: Arduino EtherShield v1.1 won't talk to Uno with strange baud rate on: July 23, 2014, 08:09:57 am
Hmm I have multiple chips... Would it make a difference if I try to (re)burn the correct bootloader?

It shouldn't.
13  Using Arduino / Project Guidance / Re: shaking servo's on: July 22, 2014, 08:19:50 pm
Are you using anything else?  SoftwareSerial disables interrupts while characters are being sent or received so that can cause servo jitter.  It might also be a wiring problem. If you don't connect servo ground to Arduino ground that can cause bad behavior.
14  Using Arduino / Networking, Protocols, and Devices / Re: How to get commands to arduino non locally without configuring router. on: July 22, 2014, 08:17:12 pm
Perhaps your router supports UPnP (Universal Plug-and-Play).  There are utilities that let you configure port forwarding through the UPnP protocol.
15  Using Arduino / Installation & Troubleshooting / Re: Arduino EtherShield v1.1 won't talk to Uno with strange baud rate on: July 22, 2014, 07:38:50 pm
Sounds like the replacement ATmega328P chip has the Duemilanove bootloader instead of the UNO bootloader (optiboot).  That should not cause a problem with the ethernet shield.
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