Technology choices for simple mcu -> computer transfer

Wireless & IoT
1

Hi there. Trying to start up a more ambitious project with a friend involving relay of information from custom devices to and from a computer (via RF) running a web service of sorts. However we want to start small and the first order of business is just getting a mcu talking to a computer via RF.

I’m fairly new to embedded systems and electronics, and can’t say I know a world about RF, but I know enough to get around and be dangerous. I’ve successfully worked with C and writing custom firmware for an ARM prototype board and was able to grudge may way through it pretty well and accomplish everything I wanted.

Really what we need advice on is what technology choices we should make. We’re trying to way cost vs. flexibility and programming effort. Essentially for the first test we’d love to just exchange data between a computer and an RF device, and that could be as simple as possible. However the future direction of what we’re trying to accomplish involves the need for more sophisticated data transfer protocols, and potentially larger amounts of data/files.

I’m wondering if anyone out there with more experience can lend some guidance. It seems like the lower cost RF solutions will provided the most flexibility since the data protocol essentially would be crafted by hand by us, but also be the most work to implement (and I’m not really sure we need that kind of flexibility). Serial communications should be sufficient for the time being. Range is not a huge factor, the further the better, but 40m should be plenty for now.

Essentially the goal would be to have a transceiver hooked up to a computer somehow talking to the computer through some sort of custom driver (the least amount of “ground-up” work we have to do for now, the better). It should be able to poll for devices (the mcu with RF) in its proximity and attempt to establish a communications with them. From here there would be a set routine to transmit and receive data. The computer would be hooked up to a web service relaying the data (doesn’t fully relate to the topic other than context).

Can anyone offer some suggestions that would would point us in the right direction? We don’t want to spend a ton on the RF technology, but at the same token we don’t want to have to spend tons of time hand coding all of our protocols and transmition/error checking routines, also polling and broadcast, etc. Looking for a good balance of price vs. immediate utility. Smaller form factors are preferrable.

Thanks,

-Mike

2

super easy way low cost is a maxstream XBee or Xbee pro module. Plug and play. Just use the module; not development system needed.

http://www.maxstream.net/products/xbee/ … zigbee.php

with apologies to SFE - I wish the XBee’s were sold here, along with a baseboard/breakout board.

3

it depends on what you would like to do in the end, but i quite liked the meshnetics zigbee modules. reaching a range of 500m (in prefect conditions) and still asking only 18mA tx and 19mA rx current.

http://www.meshnetics.com i think they come preprogrammed with thier Z stack software that let you easily configure them up into a mesh network. I am ordering an evaluation kit so will let you know how they actually work.

btw price is around pounds 30 per module in the UK

4

There are lots of approaches that would works. The xbee modules mentioned are fine. people have gotten good results with the HAC-UMxx products (sold by SFE). Or you would go the wifi route with modules from digi intl. The advantage of wifi is you don’t have to build anything on the PC side.

You didn’t say what kind of distance and data bandwidth you need which makes it hard to give you good advice.

5

OK !!

My mistake, meshnetics modules are not pound 30 each but dollar 23 each.

Regards

6

meshnetics, like the Maxstream XBee, are 802.15.4 with zigBee optional. Low cost.

Because meshnetics is based in Moscow, and I’m in California, and because their US-based support staff is minimal, I went the XBee route.