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1  Using Arduino / Interfacing w/ Software on the Computer / Re: Compatability issues with Arduino Uno and Arduino Mega on: Today at 10:08:48 pm
The standard Mega uses the same cable and power source as a standard Uno and the gear is interchangeable.

I don't know what the overall power limit is but the power per pin is the same 40Ma, and I imagine the overall is too. Since you want the pins, an external power source for what is on them may be necessary.

If you are using the USB cable for power, it might be a good idea to get a wall wart.

2  Using Arduino / Networking, Protocols, and Devices / Re: Factory reset of HC-06 on: Today at 09:52:41 pm
Hi, is it possible to factory reset the HC-06?

I experimented with setting a baud rate > 115200 (AT+BAUDA 460800). 

I don't think there is a reset per se

I understood the command for 115200 is AT+BAUD8. The HC-06 runs fine at that rate and maybe you have just sent a dodgey command. Maybe you can still return with AT+BAUD4.
3  Using Arduino / Project Guidance / Re: two water pump project for newbie on: Today at 09:22:18 pm

a) the pump seller said the pump has to work with a motor shield (I can get a L298N or L298P), is it necessary OR enough for powering that two water pumps?

There is no obligation to use a motor shield. All you need do is ensure the output current of the pin on the Arduino is not greater than the maximum specified.  The ability of the shields you quote depends on the power rating. In the picture you show, Arduino isn't driving a motor, it is driving a relay. If the coil current is within spec, it will be fine.

b) What about the power? Would it be OK if only attach a 9V battery to the UNO?

If you mean the little rectagular 9v, probably not. They are made to deliver volts, not power and really aren't any good for powering anything. A decent pack of 6xAAs might work quite nicely, depending on how long you want to run it, but could cost more than a wall wart.

c) I found a reference diagram (attached), i don't understand about the relay breakout part (relay = motor shield?)
The relay is doing what a motor shield might do. I imagine some motor shields have relays on them.
d) btw, normal water pump is one way, right? (not like motor when change the +/-?)
No, it depends on the motor. The pump needs to go one way to work but, if you wire it the wrong way, it might run backwards and not work.  The best thing to do is follow instructions.

4  Topics / Home Automation and Networked Objects / Re: Bathroom automation and waterproofing devices on: Today at 08:45:25 pm
additional important details.

I think it's time to read reply #1 again. All this stuff is just a case of re-inventing the wheel, and the end result is an expensive square one.
5  Topics / Science and Measurement / Re: Liquid Usage with a meter from Adafruit on: Today at 06:23:57 pm
Rate is the problem, not quantity. It's not a matter of maths, it's a matter of scale, and depends on when the quantity is assessed.

For me, as I said, display update is once per second, quantity is litres/day.  For a hydroponic greenhouse operator, rate may be litres/day and never know there might be a problem.

Read reply #7 again. Better still, try it for yourself.
6  Using Arduino / Displays / Re: TFT LCD Mega Shield V1.2 Pin assignment/layout on: Today at 03:07:31 am
I believe Cold Tears has cable for that. Alternatively, you could use M+F rainbow ribbon, which is available in a variety of lengths.
7  Using Arduino / Project Guidance / Re: Controlling 4 Digit 7 Segment Display on: April 15, 2014, 06:28:13 pm
Are you sure the wiring diagram is correct? The first thing to do is count the number of pins. If it really is 12, then check to see if the the dp and/or colon really works.

There are two things here that are beyond comprehension:

1. A situation where a user actually requires the dp and colon alight at the same time.

2. The company that made this is still in business.

In the light of 2, there probably isn't much point in trying to ask the company that made it, as they probably aren't.. If dp and colon really are on one pin, you might return it for refund - "not fit for purpose".

8  Using Arduino / Displays / Please help identify this display on: April 15, 2014, 11:21:37 am
I have had this TFT from Cold Tears for about two years and have never gotten round to using it.

I don't know what it is but I now have it running by using the Henning Karlsen UTFT library. I am using 480x320 resolution but it clearly isn't right. There is a line at the bottom missing, and the stuff that should be centred isn't

If I change the code for the bottom line from 307 to 227, I can see the line. This suggests that the display is 240 high but, if I use the 400x240 or 320x240 demos, I just get a white screen. In the 480x320 demo, I had to uncomment a line for use with Mega. I don't see a similar trick in the other demos.


I have now gone through my tax files and found that this is a 400x240 display but I still don't know the model and I cannot get a 400x240 demo programme to work.
9  Using Arduino / Networking, Protocols, and Devices / Re: Bluetooth Bee question and support on: April 15, 2014, 10:36:29 am
That is a plain vanilla HC-05 bluetooth module on a proprietary backboard which I believe is exclusively for use on an Xbee shield. I believe the pin spacing prevents you from using a standard breadboard. You may find that four jumpers are all you need to connect 3.3v, gnd, rx, tx to Arduino, with a 3.3v divider on the Rx pin but, since you have paid so much money for it, you might as well cough up some more and get the shield for which it is intended. It then becomes a simple plug'n'play job, and it probably then gives you a lot of extra features as well.

Here is some background on using the HC-05
10  Topics / Science and Measurement / Re: Liquid Usage with a meter from Adafruit on: April 15, 2014, 10:16:09 am
The display update was 1hz. I am dealing with mains pressure water with straight pipe 200mm each side. The actual flow would be about 5 l/min  but the readings are all over the place 2.13, 6.29, 4.96, 3.45, that sort of stuff, and by the time you have understood one reading that is so different from the one before, you have missed the next two. Not that that matters, as you have no idea which one to use anyway.

The problem was not so apparent with my Swissflow axial flow turbine, but that was using the frequency meter on a DMM, I never used it with Arduino. I did have a bad time with it, the problem may actually have been the same, and it may be a characteristic of all hall-effect turbines.

I have not progressed any further with this but rate is vital for me and I have to resolve it. I'm sure it can be fixed by either averaging ten readings or simply making the count period ten times as long, or something like that.
11  Topics / Science and Measurement / Re: Liquid Usage with a meter from Adafruit on: April 14, 2014, 07:04:56 pm

 Sorry misread the above post

If you are referring to me, that is the programme I was referring to. I stripped down to just read rate and total, no buttons. This is to go with a turbine sold by Jaycar, but will work with any of that ilk. You just need to change the calibration factor. The three I use all have their calibration in the data on eBay and were then adjusted after testing.

After serious long-term testing, it is clear this rig is extraordinarily accurate, around +/- 0.5% error, which might be as good as the Maddalena meter it was being tested against.

Instant flow rate is useless as the programme stands, but the total flow accuracy suggests that getting an average over ten seconds would work. My commercial meter might be doing the same thing anyway and only updates the display every 30 seconds.

12  Using Arduino / Sensors / Re: grouping temperature sensors on: April 14, 2014, 10:40:46 am

It is certainly at least Arduino compatible because it is mounted on Arduino Mega (it is not visible in the picture but if you have doubts - i can make a picture of a back side of device).

Apart from the words "Mega power supply", which could be meaningless, there is nothing  on the data sheets that even vaguely suggest it has anything to do with Arduino, and quite a lot which suggests it hasn't - .like 48v wires. Information on how it connects to Arduino would be more informative.  You really need the programme that is in it too but, once you have sorted the connections out, you might be able to write a new one. I believe the screen is one popular on Arduino, so there should be no problem with that.

And what makes you doubt that it could work with 3 sensors? In a scheme attached (pdf) you can see three sensors plugged ???

I don't doubt it will work with three sensors. I do doubt you are going to get it to work - with any - but, if you do, it is likely to work fine with five. This would surely be the case if it polls the DS18B20s by index rather than stored addresses.  

13  Using Arduino / Project Guidance / Re: DS18B20(solar heating) display through webserver - need help(now with LCD) on: April 14, 2014, 08:57:09 am
Those are the addresses of the thermometers.

If you did not get them yourself and still need to do so, check here
14  Using Arduino / Sensors / Re: grouping temperature sensors on: April 14, 2014, 08:37:43 am
it is not that i am hiding something - just not sure what is it.

Well there is probably no surprise about that.  I suspect the only people who know what it is are the original manufacturer and the original person who was supposed to receive it as what I imagine is a replacement module, which isn't you.

While the device is about the size and shape of a shield for an Arduino it clearly isn't one and has nothing to do with Arduino. It appears to be part of the controls for a refrigeration system. 

What harm can i make to a device if i connect 2 more sensors just to try

In the highly unlikely event that you can make it work with three DS18B20s, you can very probably make it work with five. You certainly won't do any harm but it seems the speculation in my previous was right - it's something to be hacked for spare parts.
15  Using Arduino / Displays / Re: Differences between lcd.begin() and lcd.clear() on: April 13, 2014, 11:42:52 pm

I am currently back looking at hardware issues, focusing on the display ground (easier at this time than placing it on a separate power supply).

You shouldn't need to have separate power to the display, have it entirely driven by Arduino and check for external nasties like relay coils and contact spikes.
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