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1  Using Arduino / Networking, Protocols, and Devices / Re: using nRF24L01 and Wiznet ethernet shield on the same Arduino on: March 31, 2014, 08:47:29 am
I've been trying to get the nRF24L01 and the Wiznet Ethernet shield working on the same Arduino for a while now, but have not had much success.  Specifically, I have a gateway Arduino w/ ethernet shield and nrf24L01. I'm trying to update Xively with a remote sensor node communicating with the gateway via nRF24L01.

I know you can't use both modules at the same time, and you need to set the select pin on the nRF24L01 such that it's different from the select pin of the Wiznet.  But there must be something going on with the Xively module.  I read somewhere I need to issue a stop command to the ethernet shield...not sure how to go about it.

It seems like such a common thing to want to do.  Ethernet gateway with nRF24L01's acting as network to remote Arduino nodes, updating to Xively.  But I haven't found any examples of other people doing it.

Any advice would be appreciated.



i have both working fine on a arduino duemilanove
pins are:
CE           -> arduino 8
CSN         -> arduino 9
SCK           -> arduino 13
MOSI     -> arduino 11
MISO     -> arduino 12

then on your setup you define
RF24 radio(8,9);
and voila, you can use ethernet and nrf together.
I'd suggest you try the GettingStarted example from rF24 library and see if the printed details look good
then you can start to play with ethernet library too
2  Using Arduino / Networking, Protocols, and Devices / Re: 433 Mhz RF signal cloning on: February 12, 2014, 09:29:42 pm
Thing is, the remote has a dip switch has i said before, and its value is 01010001 or 10101110 (dont know for sure because there's no indication if up is 1 or 0, so one of those values is the correct one )
so the output .wav file must contain that value 01010001  or 10101110 , and according to my analysis (picture below) it's no manchester coding, we can interpret 0 and 1 just looking at the bottom of the pulses (but i might be totally incorrect! )

I dont really need to understand what is the content of the data, just need to understand the minimum to be able to transmit it

i've lent my sdr, will capture some more samples again when i have it back
thanks for your time Rob smiley-wink
3  Using Arduino / Networking, Protocols, and Devices / Re: 433 Mhz RF signal cloning on: February 12, 2014, 02:03:39 pm
Riva, how can i measure the short and long pulses length to begin with ?
Using a logic analyser to capture the data and measure is easy but you seem to be using Audacity? Can zoom in enough to mark off the lengths of the highs and lows?
Failing that I did try to elicit help/support for an Arduino logic analyser here but got no offers of help so abandoned the project but it may be just about usable enough to measure your waveform.
@Riva:
Sorry for long time to reply but i have been busy with some other work.

Attached is what i captured with rtlsdr , if you could give me some directions to how to understand and measure high/low pulses width and pulse length from that .wav file, that woud be a start smiley-wink
i also tried to apply a low pass filter and leveler effect and got this, may be it helps to understand pulses width
4  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 27, 2013, 02:51:54 pm

That was the answer i was looking for. Tottaly makes sense for me now smiley-wink
So i must find a trickle charger that is able to provide at least 1.3A, but isnt that too much for constant charging the battery?

I'm not sure how you reconcile the words in bold with your subsequent sentence ... which underscores my comment that it was hard to know how to answer your question.

The reality is that you aren't going to make sense of stuff on this forum until you learn the basics of electricity - amps, volts, ohms and watts would be a good start. What's more, until you learn that I worry that you are going to misinterpret the advice here with expensive consequences.

...R

English is not my native language, so may be i didnt express exactly what i wanted.
It makes sense for me, the charger <-> battery question i had about how did the charger knows when to stop. And you explained it, in a way that makes sense for me.
The other thing, about the amps that the charger must have...
from what i read, the charger needs to be low amp, so it will slowly charger the battery, however for powering both arduinos + solenoid i need 1.3A, so may be i need to use a 1.5A charger and use some sort of current divider to provide low current to battery ?

@ Paul__B
i made a typo in :

Quote
my electric door lock works by being locked every time, and unlocking when i provide power to it.
So the battery will only be powering both Arduinos, at normal operation 0.7 + 0.1A = 0.8A, and then when i need to open the door it will use: 0.8 + 0.5= 1.3A (for 10 seconds), so it draw too much power from the battery when the main power fails.
should be: so it doesnt draws too much power from the battery, because it's taking 1.3A only for 10seconds...

For now, i'll get the LM2596, the fuses and diode.
About the charger, can i use a trickle charger of 1.5A  and do what i said some lines above ?
5  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 26, 2013, 02:45:09 pm

Yes, but how does the charger and battery knows when to stop charging and continue feeding the arduinos?


It's hard to know how to answer this... I can't imagine what sort of system you think exists between a battery and a charger.

Neither the charger nor the battery knows anything. A current can only flow if there is a voltage difference. As a battery charges up its internal voltage increases. Eventually the internal voltage is the same as the external voltage provided by the charger (assuming the charger is set to a suitable voltage) and then no more current can flow into the battery. There is nothing to stop current continuing to flow into the Arduino.

...R
That was the answer i was looking for. Tottaly makes sense for me now smiley-wink
So i must find a trickle charger that is able to provide at least 1.3A, but isnt that too much for constant charging the battery?
6  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 26, 2013, 11:42:43 am

Yes, but why?
They are two independent arduinos because one is for the door and has RFID, an lcd and some sensors and the other one, is for controlling 4 relays, and a bunch of sensors. With only one, i hadnt pins to all those sensors, lcd, rfid and the nrf24l01 chip

All very well and I hope the LM2596 is much more efficient, but dropping 7V at 100 mA is 0.7 W, and even without a heatsink (which is the obvious solution), the heat should not be that bad (as long as you do not enclose the circuit too closely).
I thought the same, only 0.7W shouldnt make this hot, and also i notice that because of that the arduino starts to have a bad behaviour, rfid and lcd too. So it must be because of the hot temperature of 7805 regulator

Of course.  It is connected, so that is what it does.  It provides as much current as necessary - up to its current limit - which for a charger, it needs to be limited in some way to protect it.  But a 7812 has current limiting and thermal shutdown built-in.
Yes, but how does the charger and battery knows when to stop charging and continue feeding the arduinos?

@Hello_World_ROB :
my electric door lock works by being locked every time, and unlocking when i provide power to it.
So the battery will only be powering both Arduinos, at normal operation 0.7 + 0.1A = 0.8A, and then when i need to open the door it will use: 0.8 + 0.5= 1.3A (for 10 seconds), so it draw too much power from the battery when the main power fails.

I am NOT using arduino UNO, those are arduinos i created myself, both use 7805 regulator, and because they get too hot i started looking for switching regulators (like the LM2596 cause they are cheap on ebay)

For fuses, should i add two fuses, one for each arduino ?
For Node A that uses maximum 0.7A , and 0.8A fuse should work
and for Node B, that uses maximum 0.1A, a 0.2A fuse works too, correct?

The solenoid is being switched using a TIP120 and a diode

As for the diode mentioned several times, that should be placed between the charger and the battery, it must have a maximum current rate of 1.5A (cause both arduinos and the solenoid wont use more than 1.3A), right ?
wish one would suit this ?
7  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 25, 2013, 11:16:45 am
The two arduinos i refer, is Node A and Node B, they are two independent arduinos.

The power draw is as follows:
Node A
maximum: 0.7A

Node B
maximum: 0.1A

Door solenoid
maximum: 0.5A

total: 1.3A

I tried powering the Node B (that only draws maximum 0.1A) with 12V, and the 7805 regulator got too hot.
That's why i now bought the LM2596 dc-dc converter, to feed those two nodes with 5v and avoid the 7805 regulators.
The solenoid can receive the 12v directly from the battery.
The question that remains to me is, will the trickle charger continue to supply power to arduinos even when the battery is tottaly charged ?

So can i wire it as this image i posted before?
8  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 24, 2013, 09:07:15 pm
An UPS is expensive and i'd like to keep the thing on a diy style  and gain some knowledge
As refered by  Paul__B, the battery is only to be as a backup power, not for constant use.
Both of my diy arduinos have the LM7805 regulator and respective capacitors, but since i need to bring 12v to 5v (planning on using the LM2596 dC-dc converter cause it's cheap), i need to remove the LM7805 and the capacitors... and the LM2596 should bring a clean 5v power line to the arduinos, correct?
I am planning on using Lead acid battery, but dont know if every charger and battery combo will work as you refer (that stops charging once the battery is full)
but how does this works ? The charger will stop providing power once the battery is full, or the battery will not charge anymore and the charger keeps providing power (so it can power the arduino when it's not charging the battery)
I just need some directions on this, because this is the main question of the project... and this will help me on future projects that need to work even when the main power fail.

Yes, it should be fail-safe, but i want to keep the door locked just in case somebody brings the power down so they can enter the room.
9  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 23, 2013, 10:28:01 pm
Robin2, about the trickle charger constantly connected to the battery, wont that overcharge the battery?
10  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 21, 2013, 09:35:43 am
Ok, thank you for your help smiley-wink
11  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 20, 2013, 02:44:25 pm
Ok, what kind of diode can i use ? And also what values of resistors i need to go from 12v to 5v so i wont damage the arduino ?

About the schematic i posted, it should work, right ? Both arduinos receive the +5v power that comes from the switching regulator that receives power from the 12v charger or battery if a power failure happens
12  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 20, 2013, 09:23:04 am
Yes, the drawing you made, makes sense smiley
Where i live power failure is not very common... it can happen 1 once in a week, or 2 or 3 times in a month but for very short period, so the battery is only to prevent me being locked outside the room.

Despite planning on using 12v for both arduinos, I am having some problems with the 7805 regulators now :/
With that readings on node B, (55mA normal operation and 0.5A for 10 seconds when it opens the door lock), powering with a 12v 2A wall supply, the regulator 7805 is getting too hot (i mean, if i touch it i can burn my finger in a matter of seconds).
But according to my calculations: (12-5)*0.5 = 3.5W maximum because normaly it would be (12-5)*0.05 ?, shouldnt the regulator operate normaly with this power dissipation ?


Would this work and prevent the 7805 from being too hot ?


With that schematic how would i be able to detect if i'm getting power from charger or from battery ?
13  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 19, 2013, 09:17:18 pm
Thank you for the explanations
One thing that made me confused was the 0.5 on the 10A scale being the "exact" same value as 0.49 on the 20m scale

According to the door lock specifications sheet, it can use from 200mA to 450mA.
So 450mA plus 50mA from normal operation = 0.5A smiley-wink that right.

About the backup battery  circuitt:
(1) Over estimating power draw from the two arduinos... let's say they draw 0.6 (node a) + 0.6 (node b) = 1.2 amps
A battery with 1.5AH, would work for one hour, correct?
(2) Can you give me some hints/examples, to connect the battery/charger to both arduinos and one of them sense if it's working with battery or not ?
14  Using Arduino / Project Guidance / Re: Backup Battery on mains failure on: December 19, 2013, 08:27:55 am
Yes im thinking about a 12v lead acid battery.
About the readings can someone comment?
I would like to see a circuit showing what i need to do related to charger/battery and the two arduinos plus a detection circuit(so one of the arduinos can check if its running from battery)
15  Using Arduino / Project Guidance / Backup Battery on mains failure on: December 18, 2013, 11:03:46 pm
Hi,
I've been creating some arduino nodes with nrf24l01 and some relays to control my room and now I want to power them when there is a failure on the main power, but need some help with the current readings i got from both nodes.

First, Node A:

normal operation :


With one of the four relays ON:


So, from what i understood, Node A is consuming 42.9mA on normal operation and 110.8mA with 1 relay ON, is that correct ?

Next, Node B:

normal operation:


and because with the red probe on the 200mA MAX (bottom right side) it couldnt power the electric door lock, i had to move it to 10A and now that's where current readings made me confused
with eletric door lock ON:


http://imageshack.us/a/img812/6186/7kjb.jpg (scale 20m) it seems equal to the 10A scale shown above?! 0.5 ~ 0.49 ... CONFUSED smiley-neutral
http://imageshack.us/a/img837/7884/2tlk.jpg (scale 200m) also this doesnt make any sense to me

so at normal operation is consuming 55.9mA and it's consuming 500mA with the door lock on ?

With that questions answered i can understand what capacity i need for a battery.
Since i'm powering those arduinos with 12v, i'm gonna look for a 12v battery and charger, correct ?
(1) Now, i want them to work directly from a 12v charger (power supply) and , when there's a mains power failure, they detect the failure and work from the battery and disconnect from the battery when main power returns.
(2)  Also, i want that the arduino can detect if there was a power failure, or more simple, it knows when it's running from the battery.
I'm power
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