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1  Using Arduino / Networking, Protocols, and Devices / Re: Trouble with DMX on: July 22, 2014, 01:23:35 am
/* receiver output enable (pin2) on the max485. 
*  will be left low to set the max485 to receive data. */

/* driver output enable (pin3) on the max485. 
*  will left low to disable driver output. */

Is there any reason they have to be these values for the MAX485?  I'm wanting to put an interrupt in here but these take up the two pins I need.
Sorry for the late reply, was away for the weekend.
The MAX485's DE/~RE do not need to be on pins 2/3 and you should be able to combine them both onto the same single pin as the signals are mutually exclusive. When ~RE is low, DE needs to be low and vice versa as your not transmitting and receiving at the same time.
2  Using Arduino / Sensors / Re: Light sensor trigger on: July 18, 2014, 03:54:37 am
In your sketch you don't set pin 12 as output so doing the digitalWrite(12,HIGH) is just turning on the internal pullup resistor for that pin.

Do you need to just detect sudden changes in level but compensate for varying ambient levels of detect when the level goes over a certain value?

The below untested code will (hopefully) do a rolling average to compensate for ambient but if the value alters more than a certain value in a single step then it will trigger.
#define differenceTrigger 50  // How much a reading must differ by to trigger

const int sensPin = A0;       // Sensor input pin

int rollingAverage;           // Used to store rolling average of sensor

void setup (){
  rollingAverage = analogRead(sensPin); // Pre load average so we don't trigger on first read

void loop(){
  int currentReading = analogRead(sensPin);
  int tempResult = currentReading - rollingAverage; // Needed to ensure abs() works correctly
  if (abs(tempResult) >= differenceTrigger){        // Has it jumped more than trigger value?
  rollingAverage = (rollingAverage + currentReading) / 2; // Compute new rolling average
3  Using Arduino / Networking, Protocols, and Devices / Re: Trouble with DMX on: July 18, 2014, 02:45:47 am
The code your posted is using the hardware serial port of the Arduino (the same one used for USB) but appears to be hi-jacking the RX interrupt routine from the hardware serial so in theory you should be able to receive DMX and send to USB.
The PC serial speed would need setting to the same baud rate as the DMX (250000 baud) and some PC's serial ports might not go this fast.
A quick look at the link you supplied, the guy says he had to alter his hardware serial library to allow the RX interrupt hi-jacking.

If all you want to do is DMX receive a single channel on/off then maybe altering the code to just turn the Arduino's in build LED on off instead of sending the results over serial to the PC might help.
4  Using Arduino / Sensors / Re: Noisy square wave readings - input filter guidance on: July 17, 2014, 01:20:25 pm
Do you have either a pullup/pulldown resistor on the signal pin to stop it floating?
5  Using Arduino / Storage / Re: 16 x 2 LCD conflicting with SD card shield on: July 17, 2014, 01:17:39 pm
A quick look at the link and the LCD also uses pin 10.
    A0: Buttons
    D4: LCD bit 4
    D5: LCD bit 5
    D6: LCD bit 6
    D7: LCD bit 7
    D8: LCD RS
    D9: LCD Enable
    LCD backlight with current limiting, brightness and on/off controllable by D10.

The SD Card Shield V3.0 uses pins...
D10 – Used for CS of SPI
D11 – Used for MOSI of SPI
D12 – Used for MISO of SPI
D13 – Used for SCK of SPI
6  Using Arduino / Sensors / Re: Noisy square wave readings - input filter guidance on: July 17, 2014, 10:06:46 am
Does pin 2 still work okay as your image shows first try pumping 10V into it. You can test it by jumpering to another pin and see if it still reads pulses when the other pin is toggled.
Also (as mentioned) a common ground is needed.
7  Using Arduino / Storage / Re: 16 x 2 LCD conflicting with SD card shield on: July 17, 2014, 06:16:40 am
You will need to supply links to the shields in question but an initial thought is 1 or more pins is being used by both shields.
8  Using Arduino / Microcontrollers / Re: ST72324BJ6T6 with arduino? on: July 17, 2014, 05:57:45 am
That's a shame, all I can suggest is abandon the parts you cannot salvage or grab an IDE suitable for the ST7 (you should be able to fine free ones) and start coding. If you can get a C++ IDE (or for other languages you may know) then the basic principle should be the same.
9  Using Arduino / Storage / Re: 23LC1024 SRAM problems... on: July 17, 2014, 05:45:27 am
I am not familiar with the Nanode Gateway but a quick look online says it's a 3.3V device so maybe that's a problem. Also are you sure the pin your using for SS is not used by other built in peripherals.
10  Community / Website and Forum / Re: Forum Font on: July 16, 2014, 09:55:38 am
Which screen resolution are you using?
Of course so broken labels are not a "feature", your bad visualization may depend by some condition not properly tested by designers.
Firefox 30.0 1280x1024 (native monitor resolution)
I also suffer the font problems with Reference/Preview.
11  Using Arduino / Microcontrollers / Re: ST72324BJ6T6 with arduino? on: July 16, 2014, 07:01:31 am
Can you separate out the keypad and LCD or are they part of the main board with the MCU.
12  Community / Website and Forum / Re: Is arduino forum under stress? on: July 16, 2014, 03:12:17 am
Are arduino suffering another DOS attack?
13  Using Arduino / General Electronics / Re: Best way to power 3w RGB LED? on: July 16, 2014, 03:00:30 am
Have a look here, pretty much what your wanting to do but minus the BT. I have attached the schematic and you have a couple of spare pins to drive a BT module.
14  Using Arduino / Storage / Re: 23LC1024 SRAM problems... on: July 16, 2014, 02:52:07 am
How have you got the SRAM chip connected? Is it using breadboard and patch wires or is it soldered into a PCB?
It seems some people have problems with this SRAM and/or library though I have only once had read errors and altering the SPI clock speed cured that. I put the problem down to poor connection/noise as later test using same breadboard & arduino had no problems. Grumpy_Mike also had problems but never reported back if and how he cured them, maybe he can comment?
15  Using Arduino / Storage / Re: Why don't sdcard and rfid reader share the same pin? on: July 16, 2014, 02:28:37 am
By the way, anyone can explain me the abbreviations on sd card breakout and rfid reader, as well.
You will need to link to the devices your talking about as there are dozens of different designs using different pinouts and pin labels.
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