Which wireless technology?

[jmag999]

I am looking for suggestions on which wireless technology to use for a project.

Requirements:
Transmit 1 byte up to 3 times per day.
The transmitter needs to run off a small coin cell for a year.
Range needs to be > 300ft.
It needs to be able to wake from sleep, connect and transmit the byte within 1s.
Be as cheap as possible .

All other parameters are open.  Any suggestions for where to look?

[mjkuwp]

sounds Interesting.  I wonder... .if you are only doing this 3 times per day, why the rush to wake up and transmit within 1 second?

didn't specify where you want to transmit to?  the internet?

you can look at jeelabs.net mainly because there is a lot of low power discussion and a lot of open source code.  the hardware is pretty cheap.

also, for a newer solution

electricimp.com

check out today's podcast at theamphour.com - they have interviewed one of the electric imp team today coincidentally.

[jmag999]

The solution can be proprietary, I will have a base station to communicate with.

I need it to transmit within 1s as there is a small window when wireless connectivity will be available.  At other times, the wireless signal will be shielded.

[zapta]

Do you need a receiver to get an ack? What is the cost of a lost transmission?

Are the transmitter and base stationary? (you can use better antennas this way)

Also, is this application security sensitive?

[jmag999]

No ack required, but may be a nice feature.
No security requirements.
The transmitter and base station will be in fixed locations, but they are user installed, so I can't guarantee specific placement in every environment.

[TommyGunn]

What sort of volume are you making for this?

[hagster]

Synapsewireless RF modules will do this for you. They will easily last a year on a coin cell assuming.

Depending on your requirements it may be able to handle your IO as well, making it a single module solution.

[jmag999]

Volume will be in the 10K range.

[TommyGunn]

Oh well that changes things. I'm assuming you are building your own hardware? I think you really only have 4 options in this case.


These are more difficult to get to the range you need but much lower power.

• BLE Only a single star topology (yes BLE 4.1 overcomes this but is not readily implemented yet)
• ANT+ Same sort of specs as BLE but lower power in many cases and more flexible topologies (bit more expensive in some cases)

Better for range, but more taxing on power and higher cost

• zigbee
• Proprietary More work

How tight is are your space restrictions?

[fs]

You might like to try a TI CC1110 based solution.  Its a neat little radio, with on-chip 8051.  There are other variations (like CC1100?) that can be coupled to any MCU using SPI.

EDIT: Very low level, and obviously resource-constrained, but also super-light on power requirements.

If you want a cheap pre-made module using this chip, that is a simple serial <-> radio bridge, check out this:
http://shop.ciseco.co.uk/xrf-wireless-rf-radio-uart-serial-data-module-xbee-shaped/

The module is very handy, as the radio on the chip is difficult to program, so this way, you have a simple serial port and "AT" command set to deal with.

I've had plenty success with it, even with the simple wire whip antenna.  They have "surface mount" versions if you don't want to do the RF part on your own PCB, high power versions that claim 10km range, and some FTDI adapters that make it easy to do a base station.

I've run some of their modules, with my own firmware, with a year+ life from 4x AA batts, checking in with a base station every 30 mins.

I've no affiliation with the company; just a happy customer.

[Fuzzy]

For a open source project i used the Si4010 from Silicon Labs as transmitter.
A low cost single chip remote control chip, designed to run from a 3V lithium battery.
the only external component is a 2,2uf cap.

[mjkuwp]

@Fuzzy,

That Si4010 looks really great.  could you share a link to your open source project?

I see now the imp that I suggested earlier not a good fit for this unique application.

mark

[Fuzzy]

@mark

Sure it's here:
https://github.com/mstegen/Open-Chargeport

There are two versions here, select the one in the Si4010 folder.

It's a keyfob remote that will open the Chargeport of a Tesla Model S.
As the receiver is in te car, i only had to make the transmitter.