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16  Forum 2005-2010 (read only) / Syntax & Programs / Re: Random LED fading not working on: June 12, 2010, 11:55:49 am
HEF4794B will allow you to control 8 outputs with PWM. It's a higher current version of the 74HC595

You wire the outputs to 8 LEDs, the inputs are from ordinary digital pins on the arduino, then wire a pwm pin to the enable output pin.

This will dim all of the LED's. You can write code to set the PWM to a value and then turn on an LED at that value then turn it off and go to the next one.  

You can also tie the enable output pin high and fake a PWM in your code by rapidly turning each LED on and off.
17  Forum 2005-2010 (read only) / Syntax & Programs / Re: Shift Register on: December 17, 2007, 05:58:44 am
It sounds like you need to be using quite a few analog mux IC's. You'd scan through them looking for a change.  You'd be hard pressed to get enough pins on the arduino to run that many without expanding the digital IO as well.

This will run 8 of the pads and eat three digital pins for the address.

PulseIn flat out sucks as a command. Try and avoid it.
18  Forum 2005-2010 (read only) / Syntax & Programs / Re: timing without using delay on: December 05, 2007, 08:25:24 pm
I can point here

You may get better results if you post your code.
19  Forum 2005-2010 (read only) / Interfacing / Re: Long Distance oneWire (DS18S20) on: November 20, 2010, 07:02:23 pm

Give this a read too.
20  Forum 2005-2010 (read only) / Interfacing / Guidelines for Reliable Long Line 1-Wire® Networks on: November 20, 2010, 06:59:34 pm

It's actually "Slew Rate Control" and the document explains how to make it work.

I personally would like for them to create a 1-wire RS485 transceiver. I may look using bidirectional buffers to control data to a standard RS485 transceiver.
21  Forum 2005-2010 (read only) / Interfacing / Re: Gnoduino? on: December 31, 2010, 10:09:02 pm
You're welcome. I wanted to post the instructions which I had a hard time finding due to microscopic font disease on the website.

I'm a new user to it so I won't have any greater insight than the rest of you.

Thanks for the RPM instructions logic, I'd missed those and did the build install option as root.

python build install

22  Forum 2005-2010 (read only) / Interfacing / Gnoduino? on: December 31, 2010, 03:33:20 am
Is an article about how to install Gnoduino welcome here? It's the Arduino Java IDE ported to Python and intended for the Gnome desktop.
23  Forum 2005-2010 (read only) / Interfacing / Re: Serial over USB WITHOUT restart? (using #echo) on: January 05, 2011, 06:51:38 am
Would activating the pull up on another I/O pin and tying it to reset work?
I'm willing to try it if it won't result in slagged I/O ports.

24  Forum 2005-2010 (read only) / Interfacing / Re: 8-bit formula conversion to 10-bit formula. on: January 01, 2011, 03:44:45 pm
Would an external AREF like these do substantially better?,C1,C1778,C1503,C1506,P1989
25  Forum 2005-2010 (read only) / Interfacing / send serial port to LCD on: November 20, 2010, 07:37:19 pm
This is included in the arduino IDE
file -> examples -> liquidcrystal -> serial display

  LiquidCrystal Library - Serial Input
 Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
 library works with all LCD displays that are compatible with the
 Hitachi HD44780 driver. There are many of them out there, and you
 can usually tell them by the 16-pin interface.
 This sketch displays text sent over the serial port
 (e.g. from the Serial Monitor) on an attached LCD.
 The circuit:
 * LCD RS pin to digital pin 12
 * LCD Enable pin to digital pin 11
 * LCD D4 pin to digital pin 5
 * LCD D5 pin to digital pin 4
 * LCD D6 pin to digital pin 3
 * LCD D7 pin to digital pin 2
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)
 Library originally added 18 Apr 2008
 by David A. Mellis
 library modified 5 Jul 2009
 by Limor Fried (
 example added 9 Jul 2009
 by Tom Igoe
 modified 8 Feb 2010
 by Tom Igoe
 This example code is in the public domain.

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup(){
    // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // initialize the serial communications:

void loop()
  // when characters arrive over the serial port...
  if (Serial.available()) {
    // wait a bit for the entire message to arrive
    // clear the screen
    // read all the available characters
    while (Serial.available() > 0) {
      // display each character to the LCD
26  Forum 2005-2010 (read only) / Interfacing / Re: pduino+arduino mega+20 servos on: November 20, 2010, 07:26:04 pm

You could use a demultiplexer to switch one PWM to many. You would  be using it to pick which servo to send the pulses to. The only limit would be the time it takes to switch the chip to the servo and then to send the PWM to the servo. The downside is that you can not sustain a PWM, when you switch it to the next servo the previous servo will no longer be getting any PWM.

27  Forum 2005-2010 (read only) / Interfacing / Re: arduino2560  crashes after running 2-10 hours(SD) on: November 11, 2010, 12:30:12 am

28  Forum 2005-2010 (read only) / Interfacing / Re: Modbus library with 4-byte types support on: November 11, 2010, 12:24:33 am
I believe 4 byte is non-standard. You may have to rewrite the library to implement that.
29  Forum 2005-2010 (read only) / Interfacing / Re: Controlling an 8ch IC switch on: July 12, 2010, 11:45:56 pm

You have limited I/O on the Arduino but if you don't need to do much else 8 in and 8 out are possible.  Analog I/O is even more limited but to control switches or read buttons it's not needed and can act as digital I/O

You can use 8 of the Arduino digital outputs to control 8 channels on two chips. If you're feeling frisky you can use a serial in parallel out IC and get less I/O pins to control 8 OR MORE digital  outputs which will control 2 OR MORE quad bilateral switches. You do have to match the signal you want switched to the quad bilateral switches.

If this is for analog this will work well. If it's for something simple like 'on/off' then you can use the Arduino pins or the pins driving a transistor or the pins driving a transistor driving a relay.

When switching some signals with relays  you will need to do a bit of research as switching high power audio tends to cause blown amps.

Messing with household AC can be lethal.

Button inputs are easy and documented. There are examples built in to the development environment.
30  Forum 2005-2010 (read only) / Interfacing / Re: fast serial sendin on: June 24, 2007, 06:31:31 pm
It's pretty simple code but I don't know what library for USB they are using.

What use is this for the average user? I didn't know that the USB device on the board had an eeprom. smiley

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