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9691  Using Arduino / Project Guidance / Re: What are the Atmega644P options these days? on: June 16, 2013, 10:33:57 pm
$5, supports 324/644/1284 family.
PL & schematics.
onboard USB/Serial with MIKROE483 from, or offboard with your choice of USB/Serial adapter.
9692  Using Arduino / Programming Questions / Re: Arduino to Arduino. Non ISP. Non USB. on: June 16, 2013, 10:27:31 pm
Or Nick Gammon's uploader
9693  Using Arduino / General Electronics / Re: Sizing transformer for linear DC supply on: June 16, 2013, 10:21:19 pm
How about a 7.5V supply and then your 6V regulator after that?
9694  Using Arduino / LEDs and Multiplexing / Re: Board Game Position on: June 16, 2013, 10:09:34 pm
How about some MAX7219's?
Control 64 LEDs each, $1.25 each, 6 will control 384 LEDs.
Layout the LEDs however you'd like.
9695  Using Arduino / Project Guidance / Re: Usb punch on: June 16, 2013, 09:58:20 pm
Try this link - Newark has a whole series of punches available.

How much of the connector has to fit thru? The outer molded plastic, or just the metallic part?
9696  Using Arduino / Installation & Troubleshooting / Re: Uno passes loop-back test, but upload fails on: June 15, 2013, 10:49:54 pm
Do you have anything connected to D0, D1 that could be interfering with USB comm's?

Select File:Preferences, and check Verbose Output for "Upload".
What shows when you try and upload?
9697  Using Arduino / General Electronics / Re: Better understanding of filter/values for (best) audio output? on: June 15, 2013, 08:24:59 pm
You are correct xl97 - up to you to decide if the sound quality is what you want.
Make yourself a simple excel spreadsheet to select different resistor values, find a frequency that satisfies your ear.

R8 =  1.4K
C18 =  10nF


R8 =  2.8k
C18 =  5nF

1/(2*Pi*R*C) , if you double R & half C, the math cancels out. So leave C alone at 10nF, play with R.
Use a 2K or a 5K trim pot, play with it till it sounds good, measure R and put in that value.
9698  Using Arduino / LEDs and Multiplexing / Re: LED matrix - how to use 74HC595 for LED cathodes on: June 15, 2013, 02:10:26 pm
1. Yes, 0.1uF just plain old ceramic caps.

2. Gnd pin needs to be connected to Arduino Gnd, otherwise sporadic operation will be seen.
9699  Using Arduino / General Electronics / Re: Better understanding of filter/values for (best) audio output? on: June 15, 2013, 02:01:47 pm
First, there's no opamp - the LM386 is a selfcontained amplifier, the values connected around are to an AC signal in, to reduce the gain of the DAC, to set the LM386 gain at 20, and to stabilize the output per the LM386 datasheet.
The only filtering is the lowpass filter out of the DAC. The Ac coupling does induce some filtering.

If the DAC is being updated at 22K, then yes, filtering should be set to <=11KHz.
9700  Using Arduino / Project Guidance / Re: Bootloader advice for wireless transmitter/receiver on: June 14, 2013, 08:14:44 pm
Read the datasheet,

Section 27, pg 269.

There is bootloader space, there is application space.  The bootloader starts and then transfers control to the application.
If there is no bootloader, the application just starts.

Extra flash - easiest way is probably to add FRAM memory - reads/writes fast & easy like SRAM, holds data like EEPRPOM in case power is lost.

I don't know about connecting at the PC side, that's not something I've looked into.
9701  Using Arduino / Motors, Mechanics, and Power / Re: Amplify the output voltage of the arduino on: June 14, 2013, 09:30:33 am
Do you have a 10V supply available? If so, can just have the arduino output control a transistor whose output then switches at 0-10V level.
Otherwise, you need charge-pump kind of circuit such as is found in MAX232 where caps are used with switching circuitry to get +/-10V levels out.
9702  Community / Website and Forum / Re: [FAQ] Update my Email Address on: June 14, 2013, 09:27:03 am
Responding ...
9703  Using Arduino / Project Guidance / Re: Maximum frequency arduino mega 2560 can sample on: June 14, 2013, 12:31:58 am
There are lots of ways to make a Frequency to something converter.
That something can be a voltage, which the arduino can read and convert into a number from 0 to 1023. A low-pass filter will smooth the 75MHz out to a DC kind of level that is easily measured.
That something can be a time. If you take the 75 MHz and divide it down thru a counter, you can slow it down enough so that the high time and low time of a square wave can be measured. A divide by 10 counter will get you down to 7.5MHz.
Or you count the number of pulses in a time period and determine the frequency from there.
9704  Using Arduino / Project Guidance / Re: Whats the difference in models? Im a Noob on: June 14, 2013, 12:19:13 am
Uno has 20 pins that can be inputs or outputs.
Atmega1284P designs have 32 IO.
Mega has 54 (60?) IO.
All can use some kind of connection to RF modules for remote control.

Uno can be a good start while you learn C++ programming.
9705  Using Arduino / General Electronics / Re: Better understanding of filter/values for (best) audio output? on: June 14, 2013, 12:13:32 am
Yes, bigger, more signal.  At that point not much current is flowing, so it may not make much dfference.
R8/C18 make the low pass filter.
The resister limits the amount of current that can charge up the cap when voltage is rising, the cap discharges as the voltage drops. The cutoff frequency is 1/(2*Pi*R*C) which is the frequency where the output will be 1/2 the input.

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