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1  Using Arduino / Networking, Protocols, and Devices / Re: HC-50 Bluetooth Module Not Discoverable For Pairing on: September 15, 2014, 06:35:13 pm
The HC-05 does not work with iPhone, but I guess that isn'r your problem.

You might find the following background notes useful

Check that the pin-row is kosher. A couple of users have had problems with solder bridges.
2  Using Arduino / Networking, Protocols, and Devices / Re: communication between two or more arduino by bluetooth on: September 15, 2014, 06:31:40 pm
HC-05 is a master HC-06 is slave only.

I think you could do this with a Mega, as it has four serial ports, but I don't think it is such a good idea. Bluetooth is fundamentally unsuited, and a proper solution with something like NRF24 is probably cheaper as they can work as a network i.e. you only need one at the base station.  Doing it with Bluetooth means a paired HC-05 on each serial port, which Arduino can address separately.

3  Using Arduino / Displays / Re: help : mega 2560 & 3.5" Tft display on: September 14, 2014, 06:05:05 pm
The SD card is not covered by the display library and depends entirely on the shield.  I imagine it is typical that you have to bridge across pads or use a jumper before you can use the SD. You also need to know which pis is used to select the card, it might not be the usual pin 4. In my case it was pin 53, i.e. it is called for both select and output.

#include <SD.h>
// set up variables using the SD utility library functions:
Sd2Card card;
SdVolume volume;
SdFile root;

// change this to match your SD shield or module;
// Arduino Ethernet shield: pin 4
// Adafruit SD shields and modules: pin 10
// Sparkfun SD shield: pin 8
const int chipSelect = 53;   

void setup()
  pinMode(53, OUTPUT);     
4  Using Arduino / Project Guidance / Re: Arduino + HC-05 bluetooth module on: September 13, 2014, 09:51:58 pm
Essentially, yes to both. Ditching software serial is also a good idea.
5  Using Arduino / Project Guidance / Re: Arduino + HC-05 bluetooth module on: September 13, 2014, 11:10:18 am
Using the hardware serial pin 2 for software serial surely can't be a good idea but the fundamental problem is probably that you are using software serial.  Don't bother wasting your time trying to justify doing that, but you might find it will work anyway, if you keep the baud rate down to no more than 9600.  Failing that, and you insist on using software serial, use something other than pin 1 for Tx

I don't see the need for the delay line, and it probably makes the 115200 baud rate a bit nonsensical.
6  Topics / Science and Measurement / Re: power measurement using arduino on: September 12, 2014, 01:19:48 am
suggest the components required for the project.

I guess that is dependent entirely on the means of generating the power.
7  Using Arduino / Networking, Protocols, and Devices / Re: easiest to use wifi shield on: September 11, 2014, 06:45:46 pm
I have been somewhat put off such devices .

Probably quite wise. One option is to use an Ethernet shield and a WiFi repeater. I already had an Ethernet shield, but if you have to buy both new it is still usually easier, cheaper, and stress-free.
8  Using Arduino / Storage / Re: Data Logger to SD to LCD on: September 09, 2014, 10:05:56 pm
I think all you need is the pixel drawing procedure, and this would depend on the library you are using. This thread

shows graph drawing using the Henning Karlsen library, which has excellent documentation, even though I had a lot of grief getting my display to work with it, and the data draw is staightforward enough.   Here, the data is from sensors, but handling it from myfile reads would be much the same.

I imagine other libraries have similar procedures.
9  Using Arduino / Sensors / Re: DS18B20 Water temperature sensor on: September 05, 2014, 09:23:25 pm
You might find this useful. It is derived from a tutorial by hacktronics

The hacktronics websight appears to have been hijacked or something

The above requires you to identify the sensors' addresses separately

// This sketch looks for 1-wire devices and
// prints their addresses (serial number) to
// the UART, in a format that is useful in Arduino sketches
// Tutorial:

#include <OneWire.h>

OneWire  ds(3);  // Connect your 1-wire device to pin 3

void setup(void) {


void discoverOneWireDevices(void) {
  byte i;
  byte present = 0;
  byte data[12];
  byte addr[8];
  Serial.print("Looking for 1-Wire devices...\n\r");
  while( {
    Serial.print("\n\rFound \'1-Wire\' device with address:\n\r");

    for( i = 0; i < 8; i++) {
      if (addr[i] < 16) {
      Serial.print(addr[i], HEX);

      if (i < 7) {
        Serial.print(", ");

    if ( OneWire::crc8( addr, 7) != addr[7]) {
        Serial.print("CRC is not valid!\n");
  Serial.print("\n\r\n\rThat's it.\r\n");

void loop(void) {
  // nothing to see here

10  Using Arduino / Project Guidance / Re: Powering Arduino in a vehicle on: September 05, 2014, 06:02:21 pm
I have been experimenting with various projects in a couple of my cars lately while powering my arduino through a cigarette lighter port. I have found that my arduino Sainsmart Nano 3.0 will flicker and sometimes and freeze a live data stream from sensors when the engine is in gear and accelerating, putting strain on the electric system. I know this is not a vehicle forum, however, I know I'm not the first to install an Arduino device in a vehicle, so I'm curious as to what the recommended powering method is for this type of thing to regulate voltage spikes and drops?

1. I have used a USB cigarette lighter adapter - glitches upon acceleration
2. I have used a cellphone power chord with the mini USB plug end on my Nano 3.0 - glitches upon acceleration as well

Maybe I should try soldering on some power wires directly to the board? What would you all recommend?

If you really are getting electrical glitches on acceleration, you might look to the rest of the car, as there could be a performance hit going on. The problem may simply be mechanical. There really isn't much to ensure a positive connection, only the springiness of the earth tabs on the sides of the charger, and one of mine was chronically troublesome until I butchered the earth to get a tighter fit. 
11  Using Arduino / Displays / Re: interfacing i2C DS3231 RTC with IIC / I2C 2004 204 20 x 4 Character LCD Display on: September 05, 2014, 10:44:05 am
I think is quite different from DS1307
Not different enough to worry about. The software is the same. It sounds like you are using a bare chip whereas I just use a module and don't know anything about shorting any pins. I imagine you don't need to know either, so just use the 0x57 in your code as I described. It costs nothing to try it.
12  Using Arduino / Sensors / Re: multiple signals to single Aruino on: September 05, 2014, 09:23:45 am
It may be possible to do what you want but it might be easier and safer to have the transmitter regularly transmit, and the receiver makes use of the data or not as required. That relieves the transmitter of any decision-making but still assures the receiver that it is working OK.
13  Using Arduino / Project Guidance / Re: Camera self-timer on: September 05, 2014, 09:05:16 am
Ah well, there you go. Trust Polaroid to do it differently............
14  Using Arduino / Project Guidance / Re: Easy and Simple Wireless on: September 05, 2014, 09:01:18 am
You forgot what is probably the most vital criterion - the range.
15  Using Arduino / Displays / Re: interfacing i2C DS3231 RTC with IIC / I2C 2004 204 20 x 4 Character LCD Display on: September 05, 2014, 02:02:53 am
This is what I use for the clock

I understand the 3231 uses the same. Note that there are two programmes, one to set the clock and one to run.

You neede to know the clock's I2C address so you can use a line like

#define DS1307_ADDRESS 0x68

for the LCD it is likely to be like

LiquidCrystal_I2C lcd(0x27,20,4);

There is a programme around that can sniff the address if you don't have it
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