JeePlugs with 5V ? « Jee Labs Talk

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JeePlugs with 5V ?

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hamlet

Hello,
I'd like to use some JeePlugs as a 5V I2C network !
Which plugs do you think I can use without trouble ?
Expander and Output plugs seems to be OK...
Also LCD but I'm not quite sure about the resistors and stuff.
I'd like also to use the RTC and pressure plugs, but the DS1340 as the BMP085 don't seems to like 5V. Do you happen to have something equivalent by chance ?
And in the description of the shield, you say that you have to let the PCB bare. I really just replace every components by wire ?
Could I use 2 plugs from the shield as 3.3V plugs and the 3 others with 5V ? Maybe with a bit of dirty cut-and-wire job on the PCB...

I hope I'm not too overwhelming with my questions...
I'd be glad to write a bit about using 5V plugs if I achieve to do so !
I'm impressed by your work, and I hope you'll continue for a long time.
Regards,

Posted 07/12/2009 22:08:52
jcw

This has been asked before - but I can't seem to find the URL right now. Ah, wait - it was on the weblog, not this forum:
http://news.jeelabs.org/2009/11/05/meet-the-plug-shield/#comments

Each of the plugs documentation pages now mentions when a plug can be used at 5V as well as 3.3V - and BMP085 isn't one of them. More and more advanced sensors seem to be going the "up-to-3.6V" route these days.

What you can do, is use the plug shield with both 3.3V plugs in the port headers and 5V plugs in the A4/A5 Arduino pins at the same time. The PCA9515 I2C level converter is clever enough to allow slaves on both buses (they still have to have distinct I2C addresses).

The docs about using the shield "bare" were a bit confusing. I've tried to re-phrase the plug shield docs page, hopefully it's clearer now: http://news.jeelabs.org/docs/ps1.html

Posted 07/12/2009 23:53:30
jcw

As for the second part of your post - thanks, and continuing a long time is indeed my intention, there's bound to be lots more fun ahead :)

At the risk of repeating myself a bit, at times - when you want to write something on the wiki, so it becomes a more permanent page and easier to find for others, email me. I'll be happy to add you as member to http://wiki.jeelabs.net/

Posted 07/12/2009 23:59:24
jcw

Darn send button... missed your DS1340 RTC comment. You could use the DS1307 instead. I've still got a couple left, so if you order from the shop and remind me when doing so, I could put one of those on the board for you if you like.

(Update: Nah, got mixed up - the DS1340Z-33 will work on 5V, sorry for the confusion)

Posted 08/12/2009 00:05:37
hamlet

Ok, thanks for the clarification about which plugs can use 5V !

About the shield, I'm not totally sure about what you said...
I'd like to use some some of the port headers with 5V, to be able to 'plug' the Plugs easily in, as I think A4/A5 Arduino pins are not conveniently placed to handle a 6-pin Plug.
Do you think I can 're-route' some of the port headers to use directly A4/A5 ?
Or does it involve too much change, in that case could you create another shield PCB for that need ?
Or maybe it would be simpler to use two shields, one in 3.3V, the other in 5V ?

Now that I come to think about it, is there somewhere an explanation of the 6 wires ?
I just found the labels : PWR, DIO, GND, +3.3V, AIO, IRQ but I can't figure out how they are used in an I2C plug...

Well maybe I should just start to buy stuff, and try to play with it !

Posted 08/12/2009 14:40:12
hamlet

One more question :
Can I use the Thermo Plug on the Plug Shield, along with I2C plugs ?
If, as I fear, not, could you imagine a shield which provide few headers connected to various digital I/O of the Arduino ? Maybe with few jumpers to choose for each header between 3.3V and 5V, and between I2C and other...
I'd like to help you on this, but I've never used anything like Eagle, and my electronic skills are really basics !
But I think that a modular plug Shield would be of interest for anybody who would like to use your fabulous plugs with any "standard" Freeduino.

Posted 08/12/2009 15:35:08
jcw

To answer your pinout Q: see http://news.jeelabs.org/docs/ports.html and http://news.jeelabs.org/docs/jp1.html

As for the rest - yes, it's all possible, but I don't quite see what the benefits would be. There's a (fairly new) "JeeNode NoRF" kit with 4 port headers. It's less "standard" than a FreeDuino in terms of hardware, but then... so are "ports" and "plugs"?

"The nice thing about standards is that you have so many to choose from" -- Andrew S. Tanenbaum

Posted 08/12/2009 18:03:31
jcw

The Thermo Plug is not I2C - can't be used on a Plug Shield. But it's 5V, you could tie it to the Arduino's I/O and power pins.

Posted 08/12/2009 18:11:10
hamlet

I currently have 2 reasons to choose a classical Arduino for my project :
- I will need a GPS, and think about using the GPS Shield from [url=http://www.adafruit.com/index.php?mainpage=productinfo&cPath=1721&productsid=98]Adafruit[/url]
- I'd like to power 5V lamp (hacked from USB stuff really), if possible without a new wire, with the expander Plug

If you can think of how to do that with a JeeNode, I'd be glad !

Posted 08/12/2009 18:43:28
jcw

GPS - I've got a serial unit here, waiting patiently for me to hook it up to a UART Plug:
http://www.sparkfun.com/commerce/productinfo.php?productsid=8266

What do you want to do with lamp + Expander? On/off and PWM control? You could do that with an Output Plug, or even with an LCD plug (which has an expander plus one transistor for the backlight control). Both can run the I2C @ 3.3V with 5V on PWR for the light.

[i]... Where Art Thou Going, so deep in the night? ;)[/i]

Posted 08/12/2009 22:32:53
hamlet

GPS, seems great but expensive...
Do you know of cheaper GPS unit I could plug in the UART plug ?
I'll try to find some myself.

If I understand correctly, with a JeeNode, I can have 3.3V I2C with 5V PWR pin ?
I didn't notice that, and it seems to fulfill my requirements !

If you want to have a more global idea of project, you can have a look at my (messy) notebook : url]http://www.google.com/notebook/public/03169397961726059967/BDSbzSgoQ7PeljtAk[/url]

Posted 08/12/2009 23:16:10
jcw

Aha, automotive context :) - just one note: cars can be very noisy environments, electrically speaking. A 3.3V or 5V level I2C bus of 20 meter around the vehicle is probably not robust enough. Maybe I2C bus repeaters can fix that, but you might want to google for "CAN-bus".

Posted 09/12/2009 00:34:49
hamlet

Thanks for pointing the noisy electrical environment problem out !
In fact I don't like the idea of CAN, which sounds to me like too professional, too expensive... And a quick search with Arduino + CAN-bus didn't show any good results.
But it's not really a problem since the I2C network around the vehicle will be for lights only, and could be switched off on the road.
The problem that I can see is more about the sensors and the power I will use, even with the engine started. Do you have any idea about how the JeeNode and others could react to be powered through [url=http://sigma-shop.com/product/43/power-adapter-10-15vac-to-12v-5v-dc-for-your-atmel-avr-or-microchip-pic-project.html]that level converter[/url] for example ?
Also I'm more and more thinking about using the RF capabilities of your Nodes, do you think there will be an issue in a vehicle ?

Posted 09/12/2009 01:19:59
jcw

Impossible for me to say - I've no experience whatsoever in such an environment. It's bound to be harsh (Faraday cage, large currents, EMP spikes, spark plugs, shifting ground potentials, common power lines). Also for RF - but it's short-range, which might help. Maybe it'll work out just fine if this is for stationary use.

That level converter looks like a dual linear regulator. Probably ok, a JeeNode adds a second level of regulation down to 3.3V - if you're concerned about power consumption, you'll need to look into switching regulators. A 12->5V linear regulator will always turn 7V into heat. But hey, start simple - then extend / improve / replace where needed to reach your goal :)

Posted 09/12/2009 01:47:03