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1  Using Arduino / Programming Questions / Re: Copying 8bits from PORTA to 4 bits PORTB on: Today at 08:33:51 pm
Or
PORTA = PINB & 0b00001111;

Are the bits at the Port B pins inputs or outputs?
2  Using Arduino / Microcontrollers / Re: Remap SPI pins (MISO, MOSI, CS) – is it possible ? on: Today at 08:29:47 pm
Only if you use software to bitbang the pins - slower than using the SPI hardware and the up to 8 MHz clock rate that the hardware offers.
SPI is nice, offers "drop & forget" transfer - and 2 directions at once!
3  Using Arduino / Project Guidance / Re: Controlling linear actuators on: Today at 08:21:09 pm
This thread dove into using relays to move an actuator.
http://forum.arduino.cc/index.php?topic=233760.0
Minimal parts, minimal cost.
4  Using Arduino / Project Guidance / Re: How to change volume of sound on: Today at 07:44:17 pm
http://www.murata.com/products/catalog/pdf/p37e.pdf
See page 12 for an example to drive a raw piezo element (vs a self contained unit).
The frequency can be from Arduino, driving 1K resistor and NPN/resistor/piezo element.

If you want it quieter, can use a frequency with a lower output level.
5  General Category / General Discussion / Re: Generating Square Wave with with modulated carrier frequency on: Today at 07:23:05 pm
I don't know then.
6  Using Arduino / General Electronics / Re: Help understanding transistors on: Today at 03:35:04 pm
Then you want N-channel MOSFET, or NPN transistor, connecting motor "-" to Gnd.
This is a low side switch.

With P-channel/PNP set up as a high side switch, between battery+ and motor, you need a Low on the gate/base to turn the device on; or an addtional NPN in front of the P-channel/PNP device.
7  Using Arduino / Project Guidance / Re: Using the Right Power Supply Setup on: Today at 03:31:27 pm
Looks ok.
8  Using Arduino / Programming Questions / Re: Better program then Sketch? on: Today at 03:30:10 pm
There are lots of alternatives.

Eried has an updated alternate IDE in the forum
UEICIDE here in the forum
You can use Notepad++, there is arduino keyword files that can be added
and there's always Atmel Studio 6 from atmel.com

I don't know about autocomplete for letting you know what's available in functions, macros, classes, libraries, etc.
9  Using Arduino / Project Guidance / Re: How to change volume of sound on: Today at 03:24:02 pm
That would work to drive a speaker.
10  Using Arduino / Displays / Re: 40 pin extension cable on: Today at 03:20:19 pm
No, I meant to the LCD.
Parallel data I am guessing, signals driven with
digitalWrite(pinX, HIGH);
etc. type commands?
11  Using Arduino / Programming Questions / Re: Sending/Receiving Data via RS232 on: Today at 03:17:54 pm
Or rather, is there an equivalent of

if (mySerial.Available() >0){
// read the next byte that came in
}
12  Using Arduino / Programming Questions / Re: Sending/Receiving Data via RS232 on: Today at 03:15:37 pm
@daflippymaster,
Let's keep the topic on track please.
You're comm's are pretty slow.
Could you connect Rx in parallel to an interrupt pin, and capture micros() in the ISR and then process the data?
13  Using Arduino / Displays / Re: 40 pin extension cable on: Today at 03:10:28 pm
How fast are the signals you are switching?
14  Using Arduino / General Electronics / Re: Help understanding transistors on: Today at 03:08:13 pm
That description requires P-channel MOSFETs. Fewer choices, pricier.
Are you sure you can't connect battery + to motor "+", motor "-" to MOSFET drain, MOSFET source to battery -/Gnd, and drive transistor gate from arduino?

You keep saying resistance - resistance, Rds, is property of MOSFETs.
If you want low resistance, and thus low voltage loss as V = IR, then you want a MOSFET.

BJT transistors have a voltage from collector that is pretty steady, independent of current. If you want to give up 0.7V of your 3V (4.5V? 6V?) in the transistor, and thus have a slower motor, go with a BJT transistor. PNP per your description, NPN per mine. Look for a low Vce at saturation, then search for the Ic current the motor needs.
http://www.digikey.com/product-search/en/discrete-semiconductor-products/transistors-bjt-single/1376376?k=pnp%20transistor&stock=1
15  Using Arduino / Project Guidance / Re: Arduino turn by turn navigation system on: Today at 02:59:39 pm
You got me there.
I don't know how you'd get the info from android.
Arduino can certainly drive a little TFT/OLED screen with info from elsewhere.
You can connect up a little MP3 card with files saying things:
turn
left
right
in a quarter mile
turn now
you missed it - turn around
destination ahead
on left
on right
recalculating

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