Show Posts
Pages: 1 2 [3] 4 5 ... 370
31  Using Arduino / Microcontrollers / Re: Different bitrate for serial TX and RX? on: August 27, 2014, 05:10:37 am
I don't see why you couldn't use Serial.begin(9600); until you received some data, then use Serial.end(); followed by Serial.begin(115200); to blast it out a burst faster, then Serial.end(); and go back to Serial.begin(9600); for a while.

What happens if more data arrives when it's set to 115200?

32  Using Arduino / Microcontrollers / Re: Using an ATtiny85 as SPI Slave on: August 27, 2014, 05:09:42 am
master must know 'how long to wait there'. Since clock is pulsed by the master; it's not a problem if it waits 'too long' as long as not too little.

I2C is preferable for this, it automatically puts the master "on hold" until the slave responds.

33  Using Arduino / Microcontrollers / Re: Power Supply for Arduino on: August 27, 2014, 05:06:03 am
You will need protection. The 12V supply in a car can be nasty.


http://www.ebay.com/sch/i.html?_nkw=12v+noise+filter

34  Using Arduino / General Electronics / Re: I2C and the Atmega328P on: August 27, 2014, 04:51:13 am
That is not going to work!

Why?

Well, given that the pull-ups are enabled by the library by writing the pin HIGH after setting it as input, to pull the line low, the library must write it LOW and set it as an output - for each time it needs to.  However, when it wants to let it rise again, it must set it as an output and because it presumes the internal pull-up will be required, it will write the pin HIGH again.  This will happen on every transaction, so merely disabling the pull-up after "Wire.begin();" will be of no effect at all - it will pull up to 5V.

You would need to disable all instances of writing the pin high in the library itself.


Wrong. The chip has a hardware I2C unit which respects the "open collector" design of I2C.


35  Using Arduino / General Electronics / Re: fading 240v lights in vivarium (Safe method) on: August 26, 2014, 04:15:45 pm
Where would be the starting point for this project?

Get some servos.
36  Using Arduino / LEDs and Multiplexing / Re: Can you power a 10 segment LED bar using less than ten pins? on: August 26, 2014, 03:04:51 pm
I have an Arduino UNO and a 10 segment LED light bar and i want to find a way to use it without using up all my pins. Is there a simple way to use only a few pins to use the bar? i plan on using a potentiometer to make the bar go up and down.

Why don't you just use a chip that does that...

eg. LM3914

http://www.ebay.com/sch/i.html?_nkw=lm3914

37  Using Arduino / General Electronics / Re: I2C and the Atmega328P on: August 26, 2014, 03:00:24 pm
Im designing a quadcopter logic board and the device is the common mpu6050, while it can accept 5V, it wont last long.

...or do digitalWrite(SDA,LOW) immediately after you call Wire.begin()


CrossRoads, interesting. I thought that you disable internal pullups by setting up fuses?

No. Use digitalWrite() when the port is output
38  Using Arduino / General Electronics / Re: I2C and the Atmega328P on: August 26, 2014, 02:59:00 pm
I am designing a circuit based on the Atmega328p. Now, since I will be running it at 16mhz im going to supply it with 5V. I need to interface with a 3v3 I2C device. If I disable the internal pullups on the ATmega328p, can i just pull up the I2C lines to 3v3 and avoid using logic voltage shifters?

Yes, but you'll have to hack the I2C library to disable the pullups (which is easy).

(And obviously not give the code to anybody else, because they haven't modified their library...or put the library inside your sketch)

39  Using Arduino / Microcontrollers / Re: Different bitrate for serial TX and RX? on: August 26, 2014, 09:44:59 am
No.

40  Using Arduino / General Electronics / Re: Mean Well ELN 60 on: August 26, 2014, 06:29:23 am
I thought the unit would automatically adjust the voltage depending on how many leds are connected. Lets use our example again,

Let's hope so.

So where does the voltage adj range come in and whats it for?

Only meanwell knows for sure.

Whatever it is, it's not worth losing sleep over (or creating two forum threads).

41  Using Arduino / General Electronics / Re: Mean Well ELN 60 on: August 26, 2014, 04:10:51 am
So what is the voltage adj range then?

As noted in the other thread: It's a thing you can fiddle with if the output isn't right.

42  Using Arduino / General Electronics / Re: Mean Well ELN 60 on: August 26, 2014, 02:58:59 am
If i go with the Mean Well ELN 60-48, the data sheet says it will deliver an LED operational voltage of between 24 and 48v. So question one is if the LEDs have a forward voltage of 3.3v, the driver will run between 7 (24 / 3.3 = 7.27) and 14 (48/3.3 = 14.54) leds. And that the driver will automatically adjust the voltage depending on the number of leds connected. Is this correct?

Yes.

PS: Minimum would be 8 - 7*3.3 is only 23.1

PPS: Many people prefer to put in a few meters of WS2811 LED strip - far easier to power and control than all that messing around with high power LEDs.
43  Using Arduino / Microcontrollers / Re: Bootloader Arduino mini Pro 3.3V 8Mhz, Upload sketch, weird on: August 25, 2014, 09:54:13 am
It's in boards.txt.

You must have taken it out when you were editing it or something.

44  Using Arduino / Microcontrollers / Re: Bootloader Arduino mini Pro 3.3V 8Mhz, Upload sketch, weird on: August 25, 2014, 09:11:02 am
Set the lock bits.
45  Using Arduino / General Electronics / Re: USB power jack needed on: August 25, 2014, 09:08:34 am
Search for "USB socket" on eBay.

Pages: 1 2 [3] 4 5 ... 370