Cheap Wireless Temp Sensor / Or forums geared more to general begging electronics?

I have been playing around with the most simplest of projects (reading temps from different areas of my house and logging that data to a database). Current I have ~6 sensors working (DS18B20 from 1Wire) using a large wire network. Adding another sensor and another 50’ of cable causes everything to stop working (I’m guessing because there isn’t enough power for everything and I am sure I can reduce wire by doing it more intelligently than running 50’ RJ45 to each sensor).

Instead I want to build a wireless transmitter for my sensors (thinking I can run more sensors and they will be easier to place). I would like the price to stay below $15 per sensor. I found this little guy through some research nRF24L01+ which seems like it does a lot for me for a pretty cheap price.

So, using DS18B20 and nRF24L01+ how could I do this?

There doesn’t seem to be any really cheap .Net MF boards out there that can reach my budget.

Also, are there any other good electronics forums I can use to find information like this?

Some folks here on this forum built this driver…

http://nrf24l01.codeplex.com/

They also have some Gadgeteer modules for the nRF24L01+ in the works. Status?

Uh, at that price point, NETMF is out, let alone Gadgeteer. Your absolute cheapest Gadgeteer solution here (cerb40) runs at around $40 per “node”, and that’s without the wireless module (which I would expect to be priced somewhere north of $15 per) and the battery, let alone battery charger, fuel gauge, etc. Gadgeteer is NOT built for price.

If you custom built your board with USBizi or the STM32, and bought cheap pre-built NRF24L01+ modules from ebay, you could hit $25 or so per node, plus battery paraphernalia, maybe less. I would guess that unless you were going for high volumes, you’d never get below $15-$20.

What you’re talking about here is really best left to the very low-resource micros. There are plenty of AVR micros (8-bit, these are the Arduino (blech) types) that are available for under $1 and require minimal external circuitry. They’re much lower power, as well. You could run one for months to years on a couple AAs, if you don’t sample the temperature often (vs hours to days for even the lowest-power Gadgeteer board, even on a beefy LiPo). Other options are MSP430 (16-bit, $1-$1.50 in low qty) and Cortex-M0 (32-bit, $2.50+ in ones) or even a PIC ($0.50-$1.00).

Note that the AVR, PIC, and MSP430 options all have DIP packages available (breadboard and protoboard friendly), while with the Cortex-M0 you’re going to be dealing with a 48-pin TQFP unless you’ve got BGA/QFN reflow abilities.

Hi XenoPuTtSs,

I’m doing exactly the same thing, building a wireless temperature sensor but my goal was to keep it under $10 for each.
The way I’m doing so is by using and Atmega328, Nrf24L01+, DS18B20 and some other cheap components.
If you would like to discuss, I’m always on the IRC channel, feel free to pop in (see below)

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Pop in the TinyCLR community IRC channel and ask/chat

about whatever you want.

Details here: http://www.tinyclr.com/forum/topic?id=7210

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ianlee74, thanks for the link. Ill be using that for sure.

godefroi, the price points you came up with are pretty much what I found also. I was just hopping that there was some magical <$10 .net MF board lying around that I couldn’t find on my own searches.
Ill probably end up going with one of those other micros for these sensors. But alas, that would be a whole nother development kit to research and understand.

EriSan500, We will be in touch if you are working on the same thing.

The CHEAPEST netmf capable CPU is between $6 and $10 in large quantity, so, no, you won’t get a board for $10…

I have designed a board with the nRF24L01 on, and a PIC18F cpu, with coin cell holder, but I can’t get the nRF24L01 talking(and I don’t have time to spend to try and get it talking), but even that will be $20…

you can always build this:

and try to make it talk to a NETMF Board… i think Eric may have taken a stab at it but not sure if he ever succeeded…

let us know how it goes.

Jay Jay: I stumbled upon the node article of his before, i never thought about looking at what he was doing with it. I will be reading more into what he is doing tonight.

GMod(Errol): What chip are you talking about?