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31  Using Arduino / Project Guidance / Re: connection of dtmf decoder MT8870 and arduino uno on: August 06, 2014, 09:06:25 am
i have a dtmf decoder MT8870 and i'd like help on how
to connect it to the 2phones and arduino then
see it function...information plus schematics
will be well appreciated.ThankYou.

 Hooking a 8870 to an arduino is pretty simple, just 4 data input pins and one dataready input pin. However your desire to "connect it to the 2 phones" is not clear at all. What are the objectives of the project?

32  Using Arduino / General Electronics / Re: Gauging Interest: Printed Circuits on Paper on: August 06, 2014, 08:41:15 am
Maybe I missed where the original poster gave the conductivity of the ink?

The folks with the idea on Kickstarter say 0.2 Ohms/square.

Square what, acres?   smiley-wink
33  Using Arduino / Programming Questions / Re: Arduino Basic Program question on: August 06, 2014, 08:17:06 am
The AVR internal temperature sensor is a subject that never fails to pop up once a year or so. It's interesting but bottom line is that it is not a useful feature and I've yet to see a useful utilization of using it in a practical project.

 On the other hand access to the internal 1.1vdc voltage reference has been shown useful for being able to calculate the Vcc of a AVR at run time, useful in battery powered projects.

34  Using Arduino / General Electronics / Re: How to connect the arduino uno to the car alternator and also to use a 7.4V bat? on: August 06, 2014, 08:08:04 am
In a auto the alternator output and the battery are the same DC power bus. Just the voltage value changes when the motor is running and the alternator puts out a slightly higher voltage then just the battery alone when not running.

35  Using Arduino / Programming Questions / Re: digitalRead reads LOW even though it should be HIGH on: August 05, 2014, 04:49:43 pm
Well the wiring looks OK, and your measurement seems correct, so that leaves your sketch code. Post and let us look at it.
36  Development / Other Hardware Development / Re: 1284p/nRF24L01+/proto dev board - Skinny Bob! :-) on: August 05, 2014, 12:27:40 pm
It's actually got an auto-power switching circuit using a Schottky that will power the 3v3 VR from the 5V rail, unless there is a higher voltage on the Vin input, in which case it will draw power from that.

 Ah, missed that feature of the added diode, thought it was just to protect the 5 vdc regulator, cleaver.
37  Development / Other Hardware Development / Re: 1284p/nRF24L01+/proto dev board - Skinny Bob! :-) on: August 05, 2014, 11:02:44 am
Only suggestion I might make is to power the 3.3 vdc regulator from the output of the 5 vdc regulator rather then feeding the 3.3vdc regulator from the Vin source voltage. That way if one was to power the board via an external regulated 5 vdc the 3.3vdc would be available?
38  Using Arduino / Microcontrollers / Re: Pro Mini programming with USBasp on: August 04, 2014, 08:07:45 pm
Good stuff.

So - and of course I would not try this using Windoze - where is your up-to-date code for the USBASP devices and a description of how else it differs from the previous?  May I presume it is also 2560-able?

Well first one must identify if their specific USBasp is of the design that matches the firmware attempting to upgrade, unfortionaly not all USBasp devices except the same firmware release. There are sellers that have and ship USBasp programmers that have updated firmware, but most don't have a clue what they are actually selling.

 Lastly I don't think any USBasp programmer can handle above the 128KB (64K words) flash memory size limit, so don't work correctly with 2560 boards. My USBasp works fine with my 1284P board with it's 128KB (64K words) flash size,, and I don't own a 2560 board but have had many report problems trying to use a USBasp programmer.
39  Using Arduino / General Electronics / Re: Simplest single-cell supercap charging circuit? on: August 04, 2014, 07:54:00 pm
Keep in mind that the USB standard for current output capacity is 500mA max and if exceeded the PC generally will shutdown the USB port. Even being allowed to use 500mA requires your device to 'negotiate' for permission in software with the USB host.

USB 3.0 has higher current capacity but is still pretty new and not on many machines.

40  Using Arduino / General Electronics / Re: ICSP Header on board, is it necessary? on: August 04, 2014, 07:35:26 pm
Hi folks,

Electronics N00B here. I've got a project that I'm working on that involves a Spark Core w/ Arduino adapter shield, an IO sensor shield, and a Seeeduino Relay Shield v 2.0. The relay shield shipped with an ICSP header pre-soldered to the board, but keeping it on guarantees that it won't stack on top of the sensor shield. The essential question I have is if it's necessary for me to keep the ICSP header on? Apologies in advance if this isn't the correct place to ask.

Not needed, all the pins used on the ICSP header are also available on the standard shield pin headers.

41  Using Arduino / Sensors / Re: My quest for analogRead accuracy failing miserably on: August 04, 2014, 09:09:05 am
int voltagepin = 1;

This looks like trouble.   The analog input pins use the defined code names  A0,  A1,  A2.....

Pin 1 isn't even a good pin to use for digital I/O,  because on most arduinos it is the serial connection pin.

No. For legacy reasons analog input pins can be addressed using three different methods, however the third method is not portable across different arduino boards (example Uno Vs Mega boards).

For example a Uno, these three result in the same analog input pins being addressed:

1.     A0 to A5
2.    0 to 5       // not the same as digital pin addresses 0 to 5, the analogRead() function  'just knows' it means the analog input pins not digital pins
3.    14 to 19

A0...A5 is the most recent and best method of using analog pins, even if using them as digital pins.

42  Using Arduino / Sensors / Re: Protecting the AD pins on: August 03, 2014, 09:16:41 pm
And r3 is there to limit current to the ad pin if all else fails.

Well it's then much too low a value as if and when the ADC internal clamping diodes conduct they are rated at less then a milliamp before damage can result.

There is no such protection that covers 'if all else fails'.  smiley-wink
43  Using Arduino / Sensors / Re: Protecting the AD pins on: August 03, 2014, 08:13:55 pm
Should work OK. R3 isn't doing anything useful so could be eliminated.

44  Using Arduino / LEDs and Multiplexing / Re: 9x9x9 LED cube on: August 03, 2014, 08:02:08 pm
Cube continues to improve!
Now 9x9x7, and have the shift register to columns working & mapped out.
Can send a byte via serial port on/off the LEDs in that and see it where expected.
You can't tell from this picture, but there is a 3x3x3 cube lit up within the outer perimter all lit up.
Now to get some animation going!

 Very impressive. Having build  a 5x5x5 cube it was a lot of fun building the cube and circuits and writing the basic scanning code. Where I burned out was coming up with nice animations and sequences. Without some kind of PC based 'visual cube editor' I found it just too tedious hand writing the patterns with simple HEX code. Now it sits on my desk just blinking via random patterns, looks great.

45  Using Arduino / Microcontrollers / Re: Burn BootLoader......... on: July 29, 2014, 05:45:48 pm
Hi to all that read this.......

Is there anyway that I can burn an Atmega328 (UNO) chip ,  so instead of the traditional pin13.
(Change it to pin9).  I want to use SPI,  and that involves using pin13. 

SPI can work fine even with the on-board pin13 led, why do you think it must be moved? It's only active in code when the bootloader code is running and once a user's sketch is working the led will not limit pin 13 use as part of the SPI bus, it just will blink with SPI data transfers.

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