Taking a closer look at these two low-cost software solutions:

uTasker

One possibility would be for me to more or less duplicate what the modules do: use an ARM processor and an ethernet-specific OS. uTasker is free to experiment with, and only $500 to buy for a product, so if it works it is a great way to go.

It has a simulator, which is very cool: I can write code for my gateway on the PC and simulate the final system. I’ll bet I could pull data in from a Zigbee system using their demo SW and then feed it to the silulator, for a complete system test?

Looking at the cost of supported micros:

• Freescale MC9S12NE64, which is $10/1, $7.50/1k at DK.
• NXP ARM chip LPC2364 which is only $8/1, $5.50/100, $5/1k. No phy, no crossover.
• Luminary Micro ARM chips (which start as low as $1.50/100 for the low end parts, look into that for other things!). Their cheapest one with Ethernet is $9/1, $7/100, $6/1k. They have MAC and PHY, and also auto crossover.

Next, look at cost of dev tools. Freescale uses CodeWarrior, but it starts to cost a lot of money at these flash sizes. They support GCC, but what platforms does it run on?

What about DHCP? Yes, it is supported.

I played around with the simulator, and looked at the docs, and I have to say that at first this seems way too complicated for me!

uP

This small-micro-optimized Ethernet stack is worth a closer look too.

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What is my Ethernet solution?

Obviously WizNet would be a cool way to go. But it seems that no one has ever said it was easy. There are no documented projects anywhere that I can find. The company site is pretty awful. They do have some code for a PIC18F I think, and I think for an AVR.

What about Rabbit? I think that this micro would make dev easy, as the source code is so well documented, and the tools and app notes etc are great. But it is a difficult micro to design in, and not that cheap (128LQFP, $12/1, $10/100, $8/1k).

Rabbit Core module with Ethernet ($75) could have a TI part ($10) added to it, for a $100 gateway solution.

uTasker is an ethernet OS for a number of platforms that apparently gets one on the web immediately. Also can run as a simulator. Finally, when you are ready to go commercial, you can buy a licence for next to nothing ($500).

How can I end up with only one main costly CPU? Well, at 1k units, the Jennic+Winbond memory solution is about $5.50, and the WizNet chip is $5 in any volume, according to Saelig. So I think in volume this raw solution is about $10. I think the Jennic radio has plenty of surplus horsepower for doing the TCP part while also doing the radio part. This may be my best bet!

If I think this is not the case, that I should divide things up firther, I am looking at a Wiznet chip ($5), a TI radio ($10), and a micro (MSP430 $5) for something like a $18-20 solution. Would this be more flexible and adaptable? Does TI make an Ethernet micro? Not that I can see. But here is a Rowley article about porting an open Ethernet tasking system to the MSP430. No DHCP. And here is a TI app note on internet-connecting the MSP430 using a raw Ethernet chip. But none of these sound like complete solutions.

Wiznet’s W5100 page has some resources worth studying, including Circuit Cellar’s article on getting the W5100 up and running with a PIC18; the Wiznet SPI guide; datasheets; and a bunch of useful FAQs.

Notable is an app note on DHCP, which I was very much hoping the chip would take care of FOR me. But no. My system must do this. Fortunately it is not too hard. Still, wanted that to happen. The app note is clear and in good English, though.

Xport ($50/1) might be a way to quickly prototype, but I worry that it is a sidetrack: there is no production path, so I might be better off doing the DHCP work myself and using a WizNet module, $20 from Saelig. However, a discussion on the WizNet forums notes that even their modules contain no MAC addresses (and that they cost $1600). Bummer.

Here is a Circuit Cellar article from 2006 about combining Microchip’s Ethernet part and an Xbee module to create a bridge. Very quick, uses UDP.

A microchip solution would be the ENC28J60 ethernet controller, a micro with stack in it, and a Microchip Zigbee radio micro, also with Mchip zigbee stack.

An option for a Jennic solution would be to prototype with a Jennic module ($23/1 DK) and a Wiznet serial-Ethernet bridge ($29 Saelig). This would be $50 or so of parts to prototype (and could be condensed to $10 or so chips cost at 1k volumes of a full custom design).

ConnectOne makes an Ethernet chip too, which is about $11/1, and who knows how much in volume. Does everything, DHCP etc, with simple AT style commands. Needs external flash, or can take info from host (so only one flash shared between Jennic and ConnectOne). Mouser sells them, at least the samples. Arrow also sells them, say $8.50/1 but no stock. If that is true, then these might well be a better way to go than the Wiznet parts. Here is an old Circuit Cellar article on using them, with simple schematic and AT command overview. Call Arrow. I read a press release from ConnectOne that says that they DON’T need external flash. So which is it?

Mouser sells the Xport module for $30/1, and a low cost wireless version for only $45/1. This would be a pretty elegant solution, but very hard to get to the commercial price point! Again, maybe the ethernet module is a useful solution for the short term, proof of concept.

This press release is for a commercial gateway, not yet out, which uses an ARM processor with Ethernet, and a Jennic 5139 micro.

This Circuit Cellar article looks at an Ethernet micro by Axis, the AX110xx. Sounds like it might be hard to use.

These guys make a very simple ethernet to zigbee bridge device using the Digi socket and an Xbee. Probably will be $150 or so.

Here is a Korean commercial gateway board which uses the Wiznet chip and Atmel Zigbee radio.

Here is a commercial gateway by Telegis which simply puts a housing around a Digi socket and a Telegis module! $180

Digi has made a cheaper version of their z-e gateway, $199. Python programmable, comes with PC software too. I think made for Xbee modules.

MAC addresses

Do any Zigbee chips come with MAC addresses? Do any Ethernet chips come with them? If not, I will never be able to sell anything, as I cannot afford to buy these things and then serially program them into devices. I’d have to shell out $5k or whatever to but a block of each.

So maybe my designs will have modules in them. But then, I won’t be making any improvements over other people’s work!

Vendors ruled out

Ember is too expensive and complex. The EM250 micro doesn’t have the Zigbee stack in ROM, and they are too hard to work with, and the tools are too expensive. The EM260 might be OK, as there is a microchip/ccs dev system for it, but what do I gain?

Components in the running

• ConnectOne $11.50/1, $8/1k
• Wiznet 5100 $5.50/1, $5/1k
• Microchip ethernet micro $4/1, $3.50/1k
• Luminary ethernet micro $9/1, $7/100, $6/1k
• Freescale ethernet micro $10/1, $7.50/1k

• TI radio $13.50/1, $10/1k
• Jennic radio/micro $12.50/1, $4.50/1k
• Ember radio $9.50/1, $6/1k
• Microchip radio $3/1, $2.50/1k

Possible Configurations

Some of the main configs I am looking at, to be studied carefully and compared for initial cost, initial time to demo, difficulty for short term, production path, cost and complexity for production.

1. Connect One + Jennic: $24/1, $12.50/1k
2. uTasker+Luminary + TI: $22/1, $16/1k
3. uTasker+Luminary + Jennic: $22/1, $11/1k
4. Wiznet + Jennic: $18/1, $10/1k
5. Microchip ethernet micro w/radio duties, + TI: $17/1, $13.50/1k
6. Microchip ethernet micro + Jennic: $16.50/1, $8/1k
7. Microchip ethernet micro + Ember radio $13.50/1, 9.50/1k
8. Wiznet Ethernet + Microchip micro (w/radio stack) + Microchip radio: $11/1, 9/1k
8. Microchip ethernet micro + Microchip micro (radio stack) + Microchip radio: $10/1, $8.50/1k
9. Microchip ethernet micro (with radio stack in it too) + Microchip radio: $7/1, $6/1k

For the last, lowest-cost option, I would need to somehow wedge BOTH stacks in the same micro. I think this is too complex, if it is even possible. Maybe what I could do is start with an extra micro, just for simplicity. Then later merge the two code bases into one, if possible.

Here is a Microchip Zigbee dev kit with a network analyzer board too ($270). Here is a dev board supporting both their ethernet controller and their ethernet micro.

One design for all?

Option number five is intriguing as I could make a single solution for everything. For $17/13, I could easily make a part which can act as either a gateway or an end device, depending on Ethernet connectivity. Maybe I should look into this further! Even if I don’t do this, I think that offloading much of the responsibility for the Zigbee system is a good idea, even if it is very expensive.

Having said that, option nine could potentially be the same solution, if I was a clever enough programmer, for half the cost.

• Wiznet+micro+TI: expensive, but compelling forall the offloading it can do for me!  And still a lot cheaper than the off the shelf solutions.  Also, I think it would be more robust to separate my code from the two stacks.   $23/1, $14/1k
• Microchip+TI: probably doable to have Zigbee code in the same micro,  $17/1, $12/1k
• Microchip+microchip: cheapest, if it is possible to wedge both stacks into the same micro, $7/1, $6/1k

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This article from Make is an overview of the nascent Open Source Hardware movement. As I read it I think “Sure, this makes sense for Make, and the Instructables people, because us revealing our work is how THEY make their money. But what about us?” and then I read the developer’s page from Chumby’s site, where they make everything open source, schematics, hardware, much of their source code, etc. How do they do that? And still make money?

I need to figure this out. This is what I want to do. How can I make money while involving the community too?

This post from Make talks about Ambient Inc’s release of their chipset and schematics so other vendors can embed their stuff.

What if I make a gateway and sell it, and I make devices and sell them. Or, I don’t make devices so much as scriptable transceiver boards that work with my gateways and web systems. Then use instructables and make etc to show people how to easily make very cool complex net-connected projects. ??

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I don’t know whether a computer can “reach” a gadget on iGoogle.

The basic Gadgets test concept is to make a gadget that gathers (weather or) data and formats it for display on an aio.  Poll this gadget (if possible) from the aio (in the test case represented by my PC).

If it isn’t possible to poll a gadget from another computer, then I could have the gadget periodically write to a text file on my own server.  This text file could be titled 465782ED49009F0B, or whatever the MAC address is of the aio.  The aio could request its own file from the server.  The file would contain only the most recent command, or could be a string of commands.

Next, how would the aio confirm receipt?  I guess by deleting the file, or deleting the contents of the file.

Now, how about if data needs to go the other way?  What if I wanted to make a gadget that passed data between two objects?  Then do files need to have input and output sections?  Or do there need to be two files?

And, is FTP harder than HTTP?

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