New Project involving Xbee modules

manie

Senior Member
Stan, I will take a pic and upload, it is my GPRS/G3/HSDPA internet connection. The signal here is 3-4 bars GPRS, 2 bars G3, 1-2 bars HSDPA (if at all). Often the signal is lost and comms as well then. Now I've been connected for near 40 hours (no comms lost), I run between G3 and HSDPA, and web page etc. downloads are visibly faster. From litterally minutes to just a few 10's seconds. As said, the number of bars are not much better, but the signal quality is obviously better, unreal...

I will have a look at the 433MHz from Jaycar, is it the same as from Sparkfun ??
 
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manuka

Senior Member
Glad it's so effective-back in 2004 (when I dreamt this "wokfi" approach) many sceptics thought I was teasing them! EXACTLY WHERE ARE YOU IN THE R.S.A?
 

manie

Senior Member
Stan i looked at Jaycar 433MHz Tx/Rx (9.95 Oz$$) as well as link below on Futurlec,

http://www.futurlec.com/Radio.shtml

Are the Jaycars and some of the Futurlec units similar or same ? The Jaycar ones are cheaper in ZAR (shipping as well) so that is obviously the one to experiment with. Will appreciate comments...
Manie
 

manuka

Senior Member
They've indeed quite a range- including the Chinese HopeRF offerings- but none look akin to the Jaycar's Keymarks => www.picaxe.orconhosting.net.nz/txrx433.jpg Aside from anything else,these have terminal ID clearly silk screened!

For simple "across the room" work almost any of the numerous el cheapo 433 devices around will do. They're so easy to use with a PICAXE that you'll almost weep! There are bandwidth & superhet versus super-regen. issues, but IMHO sensitive receivers are more desirable- some cheapies are very deaf, with -90dBi typical. The Jaycar units are ~ -105dBi, with superior ones bettering -115dBi. You pay more for FM versions,as these are less prone to RF impulse noise- any electric fences on your farm? Stan
 

manie

Senior Member
Well I've strung the first Xbee piece together, just hard wire between it and 28x1 project board. It powered first time without smoke ! Tomorrow I'll start the second unit with 2nd 28x1 project board.

@BB and @Dippy: Is that forward planning 5 months ago ? As I did not get the Xbee connect boards, now I will study how to configure the little beast for 1200 or 2400 bps.., don't worry, I'll holler when I'm stuck. This is a lot more fun than Mosfets !
Manie
 

manie

Senior Member
Stan, saw your post now. YES, in RSA electric fences and HEAVY burglar bars and VICIOUS dogs and SENSITIVE security systems has unfortunately become a way of life !!

I bought the 100A SS relay from Jaycar, only to receive an e-mail saying " we do not ship to RSA anymore as goods do not arrive at the destination.........". They will refund the amount to my card, so puts Jaycar to PERMANENT rest, SHEEEEZZZZZ, could'nt they say so on their order system or NOT ACCEPT payment from RSA ?? I suppose now I'll have to wait for their convenience when the MAYBE refund me at the end of their financial year...... "disgusted I am" says master Yoda... Hell, Rev-Ed has been shipping and Electronic Goldmine has been shipping, and ALL successfully. Oh well, you don't win 'em all do ya ?
Manie
 

manuka

Senior Member
Manie: Rascals in your part of the world are certainly a well known headache,and those not in politics are apparently worse, but at least those barking dogs should be interference free. If you're really keen on Jaycar stuff perhaps get it sent in via their NZ or UK outlets. Good luck!
 
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manie

Senior Member
Manie: Rascals in your part of the world are certainly a well known headache,and those not in politics are apparently worse, but at least those barking dogs should be interference free. If you're really keen on Jaycar stuff perhaps get it sent in via their NZ or UK outlets. Good luck!
Rascals ? ONLY ? What a circus !
 

manie

Senior Member
Having looked at the thread on "n9600" baud and the post regarding max232 chip etc. it seems that the following is true for me ??

1 I'm using USB download cable. Therefore I can communicate between laptop and Xbee module via suitable voltage divider without using Max chip... true or false ?

2 I can do Xbee setup this way too... true or false ?

3 I can communicate between Picaxe 28x1 and Xbee(out of the box) at 9600 baud...true or false ?

4 If I use 9600 baud, I could maybe suffer data loss in comms... true or false ?

What are the pitfalls using 9600 baud between laptop/28x1/Xbee and vica versa ?

Manie
 

Dippy

Moderator
1 & 2. Remember XBee uses 'true' polarity at ~3V so, if you can set the polarity of your USB - serial adaptor and it is sensitive enough then maybe fine. I can't say deffo as I don't your USB adaptor in my hot sweaty hands ;)

I have been lent (by CISECO) a USB board, which is a USB-serial chip plus an XBee connector. Works a treat.
A standard serial would require a MAX232 or another inverting / level-shifting circuit I believe.

3. If you can set any microcontroller to 9600 true polarity then you can potentially talk to XBee. That is precisely one of the good points about XBee... ease.

4.Could you suffer data loss at 9600?
Of course you could, but it is in 'your hands'.
If you send a data block (or 'packet') holding 50 bytes from your PC ,via XBee to PICAXE and just use soft Serin then yes.
If you use the Hser.. hardware serial (background receive) then you should be OK if you can write the code.
If you just send a few bytes then you may get away with a soft serial Serin - especially if you use a crystal on the PICAXE.

I have had no problems whatsoever using soft serial on a PIC reading 20 byte packets from an XBee at the 'out of the box' specs.
I have had no problems sending AT setup commands (and receiving the acknowledgements) to XBee using soft serial.
In my case it took a while to get it going as it wasn't PICAXE BASIC, but the bit-bang principle is the same.

PITFALLS? The only one I can think of is the need for greater timing precision. Hence my recommendation for using a crystal if you intend soft serial. 9600 isn't exactly super-fast, but requires greater accuracy than slower bauds.
And, (whilst unlikely but still possible) duff PCB design can introduce nasty LCRs into the signal line and may distort the pulse -esp leading and trailing pulse edges. At faster baud rates any distortion will be a bigger fraction of the pulse and increase likliehood of foul up.
Obviously you will be able to see this with your Tektronix. But, usually, you'll have no problems.
 

manie

Senior Member
"Obviously you will be able to see this with your Tektronix. But, usually, you'll have no problems."

Yeah, yeah, Tektronix indeed... mine was a lot cheaper, only 20MHz dual with small CRT, real OLD style. For digital work it helps a lot though....

Dippy, I use the Rev-Ed USB download cable. Is the output 5V there ?

It seems that setting up with a 28x1 between the laptop and Xbee, one can talk to the 28x1 with "serrxd" via the download cable at 9600bd (and 8MHz), forward data with serout to Xbee at 9600bd and do the return info in reverse with sertxd to the laptop. A little bit of coding required but can save some $$$ (not requiring extra Max's etc.) and still be able to do both data transmission as well as Xbee setup, local Xbee and remote. Do you think this is feasable ?
Manie
 

manie

Senior Member
OK, my first query (complaint ?). The Axe210 Xbee-Connext datasheet is as clear as a misty morning here on the Eastern Lowlands ! Questions, lots.... Max3232 chip, well actually a Max232N, "industry standard" and "pin compatible" to the newer 3232...

Max232N: According to Axe210 datasheet states on page 3:

1 Pin11, "T1in", how can Transmit1 be "in" ?
2 Pin13, "R1in", receiving from where ?
3 Pin12, "R1out", how can Receive1 be "out" ?
4 Pin14, "T1out", transmitting where ? There is jumper which can connect to EITHER of Xbee's Txd OR Xbee's Rxd.... Pins 11/13 seems like it connects to the stereo jack comming from the laptop...

The Max232N datasheet shows Pin11 as "input from", I suppose either computer OR Picaxe ?

I would like to be able to have comms BOTH to/from Picaxe AND laptop... good I have 2 inputs and 2 outputs, BUT, which is which and where does "this" or "that" go ? I have blown one 28x1 already, hate to do that !!! I am now thouroughly confused. Do I HAVE TO buy the Xbee Connect boards to understand the basic working ? Sorry but I do need a bit of a clearer explanation PLEASE...
Manie
 
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Andrew Cowan

Senior Member
You can build the circuits yourself - the PICAXE connect boards just make it a lot easier. I reccommend buying one - you only ever need one xbee connected to a PC.

A
 

manie

Senior Member
Sounds logical yes, but no learning curve there for future reference Andrew. Would be nice to build one yourself for a complete project. For possible sale of controller I would definitely buy the boards ready made and populated, makes economic sense then. Admittedly, must think about it...

Edit:
I require a 40x1 to do the donkey work due to the need for PLENTY anal/dig inputs and minimum 8 outputs. This 40x1 will then have to talk to "on-site" 18x and Xbee, which will then transmit data for view and RESPONSE to the office with the other 18x/Xbee. The response (if any) goes back to "on-site" Xbee Connect which must then talk back to the 40x1 to implement instruction (if any).
A bit of a round-about way with LOTS of RS232 in between. There must be a more elegant way or not ?
Manie
 
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manie

Senior Member
Manie: Ah- have you made proof of concept trials yet?
No, I need to get it all going to do proof of concept (I don't have anything to do proof with...), then it either works or does'nt.... if not, then will have to install the "Pro" with more power I think. Also there is still the option of antenna "dish" reflectors etc. Why is this "proof" surfacing so frequently ? Is there a problem with Zigbee concept ?
Manie
 

manuka

Senior Member
"Proof" arises from experience indicating a 1mW 2.4GHz signal will be marginal at 100m unless the propagation path is totally LOS (line of sight) & reasonably interference free. At the very least do some quick reception trials with 433 MHz or UHF CB gear!

Electronics is no different from numerous other fields of human endeavour! As mentioned many times before, I find the sickening 1916 Somme battlefield disaster a sobering insight into meticulous high level planning being thwarted by a neglect of fundamentals - such as mud.
 

manie

Senior Member
"Electronics is no different from numerous other fields of human endeavour! As mentioned many times before, I find the sickening 1916 Somme battlefield disaster a sobering insight into meticulous high level planning being thwarted by a neglect of fundamentals - such as mud."

My goodness, a Churchill supporter for sure !! But true. Stan, the site is quite "open" with good LOS, just have to clear a six foot (1.8m) fence on a pole really. If the distance is a problem then HOPEFULLY the third Xbee as a repeater station will help planted half way. I can even get mains power to it, so no battery problem though two 7AH 12V batteries cycling should also do. The farmer is a meticulous kind of guy and will maintain batteries, housing etc.

I do NOT HAVE even UHF CB gear mate ! Running on faith here for now. Should it fail, well then I have modules to use at home, then I'll just go the full modem route (up to 28km LOS claimed....) We'll have to see. In the meantime I'll do the boards with Picaxe one side and Max232N on the PC side.

On the Max232N datasheet it is not clear what the output Txd voltage is, seems it should be 5V as the supply requirement is 4.5V and up. I suppose I will have to put this output (input to the Xbee) through a divider same as from the Picaxe. Am I correct here ?

Thanks again for all "warnings/watchouts/checklists" that is so important to even OLDER newcomers like me...
Manie

Edit: Stan, make no mistake... I bow my head to superior knowledge and HARD GAINED EXPERIENCE yourself/BB/Dippy/Andrew et al have gained over time... I suppose sometime I'll get there too...
 
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manuka

Senior Member
M: Licence free UHF CB sets,although they look like kids toys,are marvellous tools & near essentials in regions without cell phone coverage. I've long used such 40 channel ~470MHz sets (being the local "PRS" UHF CB band) to great effect in the Oz/NZ wilds, & they're ideal for PPT(push to talk) intercar convoy coordination,camping, skiing, TV antenna alignment,"kids spy rings",boating,"fumble fingers" farming & of course emergencies. Ranges are ~3km LOS, although simple antenna can easily boost this to 10km. Heavy vegetation, mesh fences & solid buildings will cut ranges to a few 100m however-the very reason I've mentioned them for you. IMHO of course cheapie 433 MHz data units would be even better for PICAXE proof of concept...

With global prices starting at an absurd ~US$15-$20 price each,UHF CB sets are near must haves IMHO. Most ½ Watt cheapies run on AAA NiCds, so it's worth buying types with docking station rechargers for "always ready" convenience. I prefer larger Uniden types as well, as they've controls easier to use in demanding wet & dirty conditions.

Extra: Just did a google.za search & see RSA UHF CB uses 5-8 chs. on ~460MHz, with sobering prices on even the entry level Zartek ZA200 handhelds. Canyon CN-WT1 (twin pack ?) cheapies noted at R290.
 

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Andrew Cowan

Senior Member
Isn't making the ariel larger illegal?

Not sure on licence free UHF CB sets - but I know it is with other things (eg some cheap 433MHz modules).

A
 

manie

Senior Member
Andrew, a 3m x 3m Quad I suppose would be illegal, but a 12dB Yagi as sold by Maxstream etc. I don't know. Common sense must prevail, one wants to get reliable comms, not swamp the country side....

Stan: Thanks for your google in my country !!!! I never look here but will now ! Will definitely get a pair for tests and just plain use and fun afterwards...
Manie
 

hippy

Technical Support
Staff member
You would need to consult the official legislation and rules for your own jurisdiction to determine exactly what is and is not legal. The bottom line is usually that if not license exempt it cannot legally be used without a license.

My understanding of license exempt use in the UK is that specific product working within particular limits are defined as license exempt and modifications ( certainly any which take a product beyond the allowed limits ) would lose the licence exempt status, so would be illegal to use.

Where a product is not a complete unit ( eg, aerials are added after purchase ) the rules are often in the form, 'license exempt providing output power does not exceed XmW", so adding an aerial which puts output power too high would again lose the license exempt status.
 

manie

Senior Member
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manuka

Senior Member
M: That Polygon looks good (if your budget can handle it!), & it's Nordic chip set is well thought of. But it's got a very high data rate, & only low power (10mW Tx) with the Rx looking a tad "deaf", so you may well have range issues. You'll need another PCB for the PICAXE etc of course, & that D9 they've provided may be redundant hence.

I've not run across that exact Polygon setup - is it RSA made?- , but reflect that it's very akin to the cheaper Chinese Yishi & HopeRF "2nd generation" data transceivers that a bunch of us have been evaluating. If you are back to 433 then consider these Asian offerings? Most of the items shown at that RSA link are of course on 433.92MHz, the UHF ISM band ideal for many slow data rate telemetry/telecommand setups. Compared with ZigBee, 433 setup is a breeze, but (as mentioned earlier) interference may be an issue.

For the zillioneth time- you REALLY need to FIRST establish proof of concept with a simple site evaluation! Even the meanest 08M/tx/rx setup can do this- see => http://www.picaxe.orconhosting.net.nz/txrx433.jpg and => http://www.picaxe.orconhosting.net.nz/433txrxtones.jpg If you can't obtain the Jaycar tx/rx pairs due to RSA issues,then put up your hand & ask us to send you a pair. Paypal etc can handle most international needs- or maybe you can direct some RSA Stellenbosch wine our way! (All this responding makes for thirsty work). Stan
 
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eclectic

Moderator
@Manie.

Just another little voice, but, please listen to Uncle Stan. :)

The cheapo modules are excellent for simple testing.

OK, they ain't the Rolls-Royce of radios, but,
for £2 - 3 ?

I can only suggest that you buy a few
TX modules and a few Rx modules.
They are so simple to play with.

Perhaps base your decision on speed of shipping-delivery?

I've got several spare Tx/Rx modules, which I don't need,
but, I'm sure if I tried to post them abroad,

then HM C+E would send me to the Tower!

e
 
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manuka

Senior Member
I've some spare Jaycar tx/rx pairs myself- how about a trade for favourable umpiring in the next SA/NZ cricket match?! Upon reflection I'd even ponder similar for Aust/NZ OD matches. Stan
 
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eclectic

Moderator
Which products have you tried? That shop seems to have some very nice (and cheap) products!

A
@Andrew

These two, or very similar designs.
(The coil on my Rx is the “resistor” style.)

http://cgi.ebay.com/Wireless-Radio-Superregenerative-Receiver-Module-RM1SG_W0QQitemZ300265755222QQihZ020QQcategoryZ85899QQcmdZViewItemQQ_trksidZp1742.m153.l1262#ShippingPayment

http://cgi.ebay.com/Mini-RF-Wireless-Radio-Transmitting-Module-TM50-1_W0QQitemZ290293253428QQihZ019QQcategoryZ1200QQcmdZViewItemQQ_trksidZp1742.m153.l1262

I've had a couple working as part of a greenhouse monitor.
Adequate across a small garden.

e
 

manie

Senior Member
I shall listen !!!!!! I will get either direct or via your assistance, how do you disguise wine so that taxes/penalties/and duties are not incurred ?? As to fair umpiring Stan: We've suffered long enough in the days of "oppression" when the world did not "like" us....LOL LOL
 

manuka

Senior Member
Yes- quite a bit of new work with HopeRF,Yishi & Friendcom 433 MHz modiules. However the associated forum topic was becoming bloated, so we'll not post further until things further developed.

433MHz has wavelengths around 70cm, meaning woks etc (which are marvellous at 2.4GHz) are much too small to act as concentrating parabolic dishes. Classic Yagi's etc best suit 433 MHz
 

manie

Senior Member
I went ahead and bought two 433mHz RS232 OEM modules from Polygon (locally). Complete with pigtails and 1/4 wave whips. This is the unit with the D-sub 9pin plug/socket. Will be more "plug'n'play" that way, so I can concentrate on the issues to make it work and not fight the wiring.

Here is a jpg showing the general view with the chicken house 101m away. Fences are 1.8m high so a 3m pole will clear them nicely. Thoughts ?

Manie
 

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manuka

Senior Member
Well- that roof cladding looks a tad combustible, but you won't have any trouble with the neighbours! That fence indeed may be a 1mW XBee issue, so 433 MHz could be the answer.
 
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