Electronic – arduino – Using an Arduino to read data from serial device then send data over bluetooth

arduinoserial

So from a general high level standpoint I need to grab data from a serial device and then send this data over bluetooth. I have a bluetooth modem picked out. I understand how to hook it up to the arduino. I however do no know how to hook the a serial device that will talk to the arduino.

It seems like I am trying to do too many simultaneousness serial connections.

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A serial protocol mostly uses a master/slave configuration with different addressing schemes:

SPI: Serial Peripheral Interface; pins often labeled MOSI, MISO, SS or Select, and S_CLK or CLK.
- Here is a library and user guide. Pins 10-13 are used.
I²C / TWI: Inter-Integrated Circuit / Two Wire Interface; pins often labeled SDA and SCL.
- The library is included, called Wire, and here is a user guide. Pins 4 and 5 are used with the Arduino Diecimila.
1-Wire: Actually needs two or more wires -- at least power/data and ground.
- Here is a library and user guide or two. Uses any free GPIO.
UNI/O: used with some EEPROM ICs from Microchip; will likely have to write your own library.
U[S]ART: Universal [Synchronous/] Asynchronous Receiver/Transmitter; typically does not use master/slave configuration, only being used for point-to-point communication.
- The library is built in, and there are extensions (two) and optimizations. It uses pins 0 and 1.
USB: Universal Serial Bus; uses a host/device scheme akin to master/slave. Pins often labeled V_CC, DATA+, DATA-, and ground or GND.
- Although possible without, usually requires extra hardware and interpreters for 8-bit micros like the Arduino to use. Ready-made Arduino platforms have USB-to-serial converter chips for IDE communication and extensions; there are also some shields (with libraries).
PS/2: Personal System/2 connector, an old IBM PC std. connector; pins are often labeled V_CC, DATA, CLK, and ground or GND; often made interchangeable with USB sockets.
- Here is a library and guide. Any GPIO can be used for DATA, but pin 3 must be CLK.

The library NewSoftSerial by Mikal Hart allows the user to implement an interrupt-driven software (as opposed to hardware, like UART peripherals) routine for serial communications. Use it if you need to, but be aware that debugging clashing interrupts is more challenging than debugging polling routines (which is apparently what the default libraries do).

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Electronic – arduino – Data from BMA180 accelerometer into arduino is sporadic

I2C is a bi-directional data bus. You appear to be using a uni-directional level translator (likely http://www.sparkfun.com/products/8745) wired such that it can only pass data from the low voltage side to the high voltage one, and not the reverse. This will prevent you from sending commands to the Accelerometer to request data, so you would only see anything if it decided to produce data on its own. (EDIT: apparently the convert is at least somewhat bi-directional)

Further, you must tie the VIO high. By leaving it floating you are probably letting noise trigger the chip somehow to occasionally produce data.

Also note that I2C requires pullup resistors.

Switching to SPI might be an option as in that case each pin would be un-directional, however you need to drive 3 outputs from the 5v to 3.3v side (/CS, SCK, MOSI) and your existing translator only supports 2. You could build something for the third from discretes.

If you left CS and SDO unconnected you might be able to operate the chip in stand alone mode where it would reliably produce data by itself, but then you would have to make the program capable of catching the data whenever it appears, perhaps by using an interrupt (or a polling loop if you can guarantee nothing else is going on).

Here is a tutorial on modifying the Arduino itself to run on 3.3v, thus eliminating the level conversion problem: http://www.adafruit.com/blog/2011/04/19/tutorial-tuesday-converting-an-arduino-to-3-3v/

Electronic – arduino – How to read and display data from a CO2 logger connected via RS-232

I'm assuming that you can already read the string into a buffer so I will start at the buffer. Your code should go something like this (you will need to import the string library):

String wholeString = String(yourLoadedCharBuffer);
int startTag = wholeString.indexOf("<co2>");
int endTag = wholeString.indexOf("</co2>");

String co2FullString = wholeString.substring(startTag+5,endTag-1);

This gives us "5.2527637e2", you add 5 to the start tag because it is 4 characters long and you want to start at the "5", and you subtract 1 from the endtag, because we don't want the first character of it.

int eStart = co2FullString.indexOf("e");
String decimalString = co2FullString.substring(0,eStart-1);
String powerString = co2FullString.substring(estart+1, co2FullString.length-1);

char decimalCharArray[] = decimalString.toCharArray();
char powerCharArray[] = powerString.toCharArray();

float decimal = atof(&decimalCharArray[0]);
float power = atof(&powerCharArray[0]);

float finalCO2Value = pow(decimal,power);

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Electronic – arduino – Data from BMA180 accelerometer into arduino is sporadic

Electronic – arduino – How to read and display data from a CO2 logger connected via RS-232

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