Inexpensive Mesh Network

[arhi]

I tried few wireless different networking "ideas/tools" by now and those include:
- irda
- FM radio modules
- AM radio modules
- BT module

What I need is
- devices to communicate on low speed (1200bps for example or 9600)
- more then one device in the "network"
- computer to be able to be "part of the network"
- cheap & easy (usart or spi or i2c towards uC for example)

From what I saw Zigbee covers most of it, it is kinda standard in sensory network... but I'm sure there are some other solutions out there (for example I know that microchip have some Zigbee like module) ... and as I just tested some and still have not decided what to "use for future products" .. any pointers on what to try / read would be appreciated

 

[3v0]

Good question. Note that this post has a Microchip bias in that it is what I most often work with.

Read more about zigBee. It seems to be the only mesh network in the list. The MRF24J40 uses a 4 wire SPI interface and is about $3 US.

If you keep the number of nodes down some of the others could work but you would have to do a wee bit of coding to make any of them act like a mesh.
-----------------------------------------------------
My thinking/rambling.

If mesh networks existed back when I studied networking it was glossed over or called by another name. I recall fully connected networks and self healing but not mesh. I found the problem interesting enough to do some surfing.

In part what you pick depends on how network code you want to design yourself.

At first glance ZigBee looks like the clear choice to me.

ZigBee's current focus is to define a general-purpose, inexpensive, self-organizing mesh network

BT

They (wifi and BT) use the same frequency range, but employ different modulation techniques. While Bluetooth is a replacement for cabling in a variety of small-scale applications, Wi-Fi is a replacement for cabling for general local area network access.

I think the problem here is "small scale". You may have a problem with a mesh network on BT.

With naked AM/AM units you have to provide all networking software. Non trivial.

irDA. Again mostly point to point.

If you are willing to not use a mesh net there is also MiWi.
https://www.electro-tech-online.com/custompdfs/2009/02/MiWi20Application20Note_AN1066.pdf

 

[arhi]

well ... I could survive with point to multipoint network ( master + many slaves ) but I like mesh better ...

the cheapest zigbee module I can get here is XB24-AWI and it is 24$ .. that's not in any way cheap (as zigbee is advertised to be) ...

the MRF24J40-I/ML is 3.4 - 2.6$ (depending on the amount) wich is "cheap" but I'm not sure what I need "on top", seams that that is only transciever so, I need the whole zigbee stack ... is there a free zigbee stack implementation for PIC or MSP430? I need to check the part about the antenna too, I'm not verse in pcb antenna's and I do not do this professionally so I do not need xyzK$ dev tools and zycL$ software to calculate and design and then ship to a professional company to develop boards and attach chips .. I do it in my home using blue press'n'peal foil and HCL+H2O2 solution ... if possible on single side boards ... I drill holes by hand (and I cannot find to purchase darn drill press so I keep breaking drill tips) ...

BT is too expensive to even consider ... 50$ for cheapest BT module is too much, no free BT stack for any uC's that I know how to use ... it is just not worth it...

IR is interesting still, especially for one way communication where "sender" is not power limited ... you can drive "enough" IRED's with "enough" power to make the "line of sight" irrelevant , decoding is immensly simple, it is very cheap and easy to work with, easy to debug ..

The AN you linked is using the same zigbee transciever MRF24J40 but with microchip stack ... again a AC163027-4 is 40$ - tooooooooooooo much .. and I can do smd but QFN is out of mine area ... It should be "doable" with smd rework (heat gun) but I never tried...

Anyhow ... seams like not many forum visitors have experience with this kind of technology ... or everyone just uses zigbee ..

 

[3v0]

Microchp offers the zigBee stack or free.

Microchip offers a free ZigBee™ software stack, enabling lower development and system costs. With its ZigBee™ compliant platforms, the Microchip stack was written to meet the ZigBee™ industry standard and ensure interoperability. Embedded system designers can now utilize Microchip's Free downloadable ZigBee™ Stack in concert with the Microchip MRF24J40 and PIC® microcontrollers.

1.Zero-cost-license and royalty-free ZigBee™ protocol stack.

2.Efficient footprint for entire ZigBee™ protocol

3.Source-code format, allowing designers to customize their products

4.Utilize Microchip’s broad portfolio of compatible
PIC® microcontrollers

The referance design from the data sheet uses a 4 layer PCB. That is a show stopper for me. There is some talk on Microchips forum about using a 2 sided PCB. More on PCB at the end.

In the US Newark sells the MRF24J40-I/ML for $3.24 quanity 1. In 25 block units it is under $3. On Microchp direct may have similar prices.

Newark has the MRF24J40-I/ML on a PCB with antenna etc, the MRF24J40MA for $10. Browse for Products | Newark.com
The bad news is that Microchip Direct wants nearly $20.

If you are on a tight budget irDA is the choice.

I may look at the zigBee stack this summer. If possible I may alter the lower layers to allow a zibBee network of wired, radio, and maybe even IR devices.

2 sided PCBs are not much harder to make then single. Start with a DS blank. Just prior to etching mask off the other side with box/packing/plastic tape to keep the etchant off. Etch. Drill. Apply toner to side that was masked off and mask the other. Etch again.

 

[arhi]

budget is not a problem but I just try not to throw money away (as I mostly do with electronics as it is so much fun and then whenever I need 1pcs of something I immediately order 10 or 100 ... then when I want to try some "for me new tech" I go and get "one of everything" ... ) .. this time I'd like to read bit more then just go and purchase "one of all modules" - (like I did with BT - luckily I was able to sell excess modules)

I don't have locally modules with MRF24J40 for under 40$ .. will have to check what else they have and at what prices as I have a good store near me (they are microchip reseller and also have good deals for other stuff, but catalog is missing many things that they can actually get here at diecent prices...)

thanks for the quote about free zigbee stack .. that clears up some of the problems

 

[3v0]

Have you checked out the TI offerings.
I think I seen where they had a free zigBee stack also.
They are into the solution on a chip thing and the ref design for the CS1111 is a 2 sided PCB.

The Newark price of $10 each on the MRF24J40MA is nice. I suppose that if you could order from them you would. Newark is a part of Farnell. Check their link. I have no idea what you can get where because I only read english

 

[arhi]

Have you checked out the TI offerings.

getting TI stuff here ain't easy .. I can easily get stuff from olimex.com for example as they are in the neigboring country and shop near me have good relationship with them .. so headers, dev tools ..

Will check .. anyhow what I can find...

 

[RadioRon]

Atmel offers several bundles of AVR processor (ATmega64, 128 or 256) plus Zigbee transceiver chip (AT86RF230) for around $10 through distributors. They offer several stacks, at least one of which is free for zigbee, called Ezeenet. Application notes and reference designs from Atmel spell it all out.

Bundles are described here:

Atmel Products - Devices

And available from Digikey.

 

[arhi]

thanks radioron, good to know ... atmel is kinda harder to get here then microchip but I will check it out ... seams that much more "solutions" are out there then I initially knew about