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16  Using Arduino / Project Guidance / Re: Difference Between Arduino Uno & Arduino Mega 2560 on: September 10, 2014, 06:12:14 pm
Program size, RAM size and operating voltage are the main things. There's plenty of data on both.

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Rob
17  Using Arduino / Programming Questions / Re: how to avoid float variables? on: September 10, 2014, 04:07:41 am
As Budvar10 says, use integer values 10/100/1000 times larger than you need and deal with decimal points etc when the data is displayed, until then it's not important.

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Rob
18  Using Arduino / Programming Questions / Re: How to generate repetitive characters? on: September 09, 2014, 09:18:15 am
Not sure, I'm not that clued up on the nuances of compilers, bit of a black art to me smiley Certainly each 20 bytes will be contiguous.

Why do you need the strings to be zero-filled ?

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Rob
19  Using Arduino / Programming Questions / Re: How to generate repetitive characters? on: September 09, 2014, 08:56:12 am
What happens if you do

Code:
const char *options[3][20] = {
    "voltage",
    "current",
    "power"
};

There will be space after the strings but I'm not sure what values will be inserted. Maybe that doesn't matter unless you really need 0s.

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Rob
20  Using Arduino / General Electronics / Re: How to raise a component from a circuit board on: September 09, 2014, 05:14:00 am
Try googling "socket strips", also have a look at the Samtec site

http://www.samtec.com/connectors/standard-board-to-board/100-inch-square-post/sockets.aspx

They have many options of varying heights and insertion depths.

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Rob
21  Development / Other Software Development / Re: How to change rs-232 port mode to half-duplex? on: September 06, 2014, 06:56:59 pm
Good point.

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Rob
22  Using Arduino / Microcontrollers / Re: Uploading code to multiple micro-controllers simultaniously on: September 06, 2014, 05:47:15 pm
As has been noted you need a network running first, no matter what the final programming solution is. That could be I2C, RS485 etc etc. Anything that allows multi-drop. But assuming that's in place and also assuming we are talking about reflashing the chips (because just sending new parms over I2C is hardly worth talking about smiley)

Each node has a serial Flash/EEPROM/MRAM/FRAM/SRAM (let's call it EEPROM for now), part of the normal running code checks the network for a "burn me" command, having got that it reads a HEX file from the network and stores that file in EEPROM, any one or all of the nodes can do this at the same time with an appropriate protocol in place although for error reporting it might be better to do one at a time, makes no difference to the operator as there will be a program written on the PC to handle this all as a single operation.

When the nodes have successfully received and stored the new code they set a flag in the EEPROM and jump to the bootloader.

The bootloader checks that flag and reflashes the chip or not according to it's state. After flashing it clears the flag.

Another option would be to use a chip that allows code execution from RAM, I think that all ARMs can do that, in this case your "bootloader" is the main flashed code, it does similar to above then jumps into the new code in RAM. That code has to also sniff the network for the "burn me" command or maybe you have a hardware signal on the network to force the chips into the bootloader or even something like a timer that detects a break condition on the network and resets the chip. For that matter some UARTs will do that so no external hardware required.


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Rob
23  Using Arduino / Project Guidance / Re: Can you sniff RS2332 Data? on: September 06, 2014, 05:24:02 pm
Yeah ok.

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Rob
24  Using Arduino / Project Guidance / Re: Can you sniff RS2332 Data? on: September 06, 2014, 09:33:19 am
Quote
I know that if the RS232 Data is real RS232 then I will need to push it through a MAX232 or similar. But we can just ignore that I think for the moment.
How can you ignore +-12v on an Arduino pin?

Quote
Or should I actually have the RS232 Route to the Arduino and then setup a second serial port on the arduino to send the data to the external display?
No, just tap the existing wire as drawn, but see previous question.

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Rob
25  Development / Other Software Development / Re: How to change rs-232 port mode to half-duplex? on: September 06, 2014, 05:42:06 am
That shield uses a MAX232 transceiver, that chip is not able to disable the transmitter so no it is not possible to do half-duplex with that shield.

If you find an RS232 transceiver that can tri-state the driver (I can't think of one off hand, maybe the LTC2870/LTC2871) then as Westfw says you can implement half duplex yourself.

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Rob
26  Using Arduino / Microcontrollers / Re: SN74LS86 Pinout on: September 06, 2014, 01:31:50 am
I guess they were pulling your leg eh smiley

A "gate" typically has 2 inputs (although can be more) and one output and the output is high or low according to the levels on the inputs and the logic function of the gate. The particular chip is a "quad XOR gate", you can look that up as well.

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Rob
27  Using Arduino / General Electronics / Re: Exploding GSM shield on: September 05, 2014, 04:55:43 pm
Caps tend to do that smiley

Lucky you didn't fry the board.

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Rob
28  Using Arduino / Programming Questions / Re: Integers and Strings in the same serial message on: September 05, 2014, 04:33:25 pm
Quote
"Fan 1" was just an example, it could be set to "Motherboard Fan" or "Front Bay Fan" or "foobar",
OK, that's different.

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Rob
29  Using Arduino / Microcontrollers / Re: SN74LS86 Pinout on: September 05, 2014, 08:01:36 am
Please VishalSubramanyam you are talking gibberish, the 86 is a quad logic gate that has nothing to do with SPI, nobody seems to know that USBasp is, you have not stated what processor you are using.

In short you are wasting everyone's time unless you can explain the problem and the hardware being used.

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Rob
30  Using Arduino / Project Guidance / Re: Arduino schematics for commercial use on: September 04, 2014, 09:23:53 pm
Quote
Selling or marketing an unapproved, non certified product, can result in FCC fines of up to $15,000 per devise.
For people like us who may just sell a few (or even a few 100) boards don't you get around this by calling it a "prototyping device" or some such.

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Rob
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