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31  Using Arduino / Networking, Protocols, and Devices / Re: what is the best protocol to connect more than 512 devices to an arduino?? on: April 19, 2014, 11:00:35 pm
I think you will have trouble using any bus with 500+ loads hanging off it.

How fast do you need to update the nodes?

Can you split them into a few groups?

What about daisy-chaining as that has no practical limit to the number of nodes (or the distance between them depending on the speed required).

Does it have to be a single motor per node? Can you say have 4 to reduce the number of nodes to 128?


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Rob
32  Using Arduino / Programming Questions / Re: How do I move a sequence through an array? on: April 19, 2014, 10:52:03 pm
Quote
I strongly support the method suggested by @DavidOConnor in Reply #1.
+1

There's almost never a good reason to physically move bytes around in C.

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Rob
33  Community / Gigs and Collaborations / Re: Project - Will pay for completion on: April 19, 2014, 10:46:55 pm
Does it have to be a real book? If not you can place all the mechanism inside a fake one and push/pull against a fixture at the back of the book shelf. That will not require any access to the rear, drilling of holes etc and will be 100% hidden.

Of course if the object is to allow you to then remove and use the book that's a different story.

This is why people need to know everything about a project.

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Rob
34  Using Arduino / Programming Questions / Re: Understanding Interrupts on: April 19, 2014, 10:35:35 pm
You can use them wherever you like. No need to include anything, they are part of the core.

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Rob
35  Using Arduino / General Electronics / Re: blackout circuit - 300ma cc circuit on: April 19, 2014, 10:16:43 pm
Firstly, what are you talking about.

Secondly, all that and you still have 145uA "leakage" current? Wouldn't a low-side FET be easier and better as well?

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Rob
36  Using Arduino / Project Guidance / Re: Automatic plant watering system on: April 19, 2014, 10:04:51 pm
Something like this I would think

http://www.ebay.com.au/itm/Ultra-quiet-Mini-DC-12V-3M-240L-H-Brushless-Motor-Submersible-Water-Pump-New-/231021868292?pt=LH_DefaultDomain_15&hash=item35c9f9f504

It's 12v though, any reason you can't use 12v?

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Rob
37  Using Arduino / Project Guidance / Re: Automatic plant watering system on: April 19, 2014, 06:48:29 pm
Quote
Would a pump like this fit the bill?
That pump looks like it's designed to be mounted directly onto a tank, much like the car windscreen washers we talked about before. In most situations that would not be appropriate as it's a lot easier to connect a pump with proper in/outlets.

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Rob
38  Using Arduino / Project Guidance / Re: Senior Project Multi-Processor Arduino Board on: April 19, 2014, 06:31:05 pm
Yeah I remember talking about doing that.

Using FIFOs or DPRAM would just be a fun thing to play with, total overkill for a dual AVR board though, a bit like having the Nürburgring or Daytona to yourself and doing laps in a Prius.

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Rob
39  Using Arduino / Project Guidance / Re: Senior Project Multi-Processor Arduino Board on: April 19, 2014, 07:42:19 am
Quote
Multiple processors should only be introduced if there is a need to do more than one thing at the same time, not just to improve speed.
Yes that's true, especially given the range of fast CPUs these days, multi-CPUs is a pet hobby horse of mine and even I struggle to justify it and for simple speed increase I can't at all.

In areas like offloading time-consuming IO (like the Lynxmotion SSC-32 Servo Controller) or maybe handling a complex serial protocol (technically the W5100 or FT232 are co-processors) I think there's a place for them.

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Rob
40  Products / Arduino Due / Re: Bill Of Materials (BOM) required for Arduino DUE on: April 19, 2014, 03:16:48 am
Arduinos are open source right? So is there not an official BOM and correct schematic available?

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Rob
41  Using Arduino / Project Guidance / Re: Senior Project Multi-Processor Arduino Board on: April 19, 2014, 03:10:15 am
For two CPUs some FIFOs  or dual-ported RAM would be fun to play with.

I'm currently working on a system that can have a master and 15 co-processors, loosely coupled with either SPI, UART or I2C.

Don't ask my why you would need 15, it just seemed like a nice round number smiley

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Rob
42  Products / Arduino Due / Re: Small-footprint Due on: April 19, 2014, 02:55:17 am
You want to be careful about feature creep, I've done two Due-compatible designs now and in both cases they got too big and complicated so I ditched them.

OTOH it's a shame not to have all the SAM features smiley

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Rob
43  Using Arduino / Programming Questions / Re: Having issues using an Arduino to emulate a shift register. Details inside. on: April 18, 2014, 06:29:04 pm
Thanks, that gives me a better idea of what's going on.

Looking at the 4014 data sheet I'm not convinced that code is right, presumably it does work but everything is done on the clock's rising edge not on the load edge.

Anyway I've done a new version.

Code:
// S88 pins setup
#define S88DATAIN 5
#define S88DATAOUT 4
#define S88CLOCK 2
#define S88LOAD 3

#define N_REGS 2
#define N_BITS (N_REGS * 8)

byte S88DataOutShiftRegister[N_BITS];
int rd_index = 0;
int wr_index = 0;

// S88 test data, when this works completely I want to add the wireless stuff to manipulate this data array.
uint8_t S88data[N_BITS] = {
0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1
};

void setup() {
  attachInterrupt(0, CLOCK, RISING); // Interrupt stuff for the CLOCK
  pinMode(S88DATAOUT, OUTPUT);
}

void loop() { // No loop stuff because it's all interrupt driven.
}

void CLOCK() {

byte dataInBit = (PIND >> S88DATAIN) && 1;
byte loadBit = (PIND >> S88LOAD)  && 1;

if (loadBit) {    // LOAD (PE pin on 4014) is asserted
// put the test data into the FIFO
for (int i = 0; i < N_BITS; i++) {
S88DataOutShiftRegister[i] = S88data[i];
}
rd_index = 0;
wr_index = 0;
} else { // LOAD is not asserted
// Get bit from upstream unit and add to FIFO
S88DataOutShiftRegister[wr_index++] = dataInBit;
wr_index = wr_index < N_BITS ? wr_index : 0;
}

// setup data out so it's at the right level for the downstream unit when the next clock occurs
if (S88DataOutShiftRegister[rd_index++])
PORTD |= (1 << S88DATAOUT);
else
PORTD &= ~(1 << S88DATAOUT);

rd_index = rd_index < N_BITS ? rd_index : 0;

}

As you say I don't have that gear so can't test it, I can't really set up two Arduinos (or indeed any hardware) right now either as I'm in the process of building my workshop and everything is in total disarray.

Anyway you don't have to go this way of course, you may feel more comfortable with the more inline approach used by GuyA's code, but it's worth plugging this in to see what happens.

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Rob
44  Products / Arduino Due / Re: Building an LCD TFT library for Arduino DUE on: April 18, 2014, 06:18:05 pm
Have you got a frame rate (or update time) for drawing a full bitmap?

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Rob
45  Using Arduino / Networking, Protocols, and Devices / Re: Serial communication (Arduino Mega 2560) on: April 18, 2014, 03:29:25 am
Quote
Moreover, the Serial1, Serial2 and Serial3 functions do not give any output on the screen.
Are they connected to a serial port on the PC? If so how, because that would require 3 USB->serial converter cables or dongles.

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Rob
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