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I am running an application that takes information and sends it over the serial port, with some processing etc done on my proprietary board (using an ATMEL simple Micro-controller). I am testing to check on how much stress I am putting on the micro-controller to verify what I will use later on with my application depending on the stress levels I see.

Now serial is one thing, but I would like to communicate wirelessly to transfer my information (can be from a few kb to a couple mb of information). Should I see any major differences in the stress on the processor if I'm communicating through serial as opposed to RF?

I have never really done anything with RF before (I'm a student), so I'd like to have some sort of idea on the different amounts of stress on this could induce compared to serial comm before I actually buy some more parts.

Thanks!

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  • \$\begingroup\$ What kind of "stress" are you worried about? Many RF data communications modules have serial interfaces anyway, so as far as your microcontroller is concerned, there should be no material difference. \$\endgroup\$
    – Dave Tweed
    Sep 27, 2012 at 1:48
  • \$\begingroup\$ Well I mean processing power, for example if I'm running at 60% processing just spitting it over my USB into my PC, would I expect any considerable high amount processing needing to be done if I was just passing it to the RF serial interface? I plan on trying out zigbee, though haven't made a final decision yet. \$\endgroup\$ Sep 27, 2012 at 1:49

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"Serial communication" and "RF" are very broad terms - there are many different protocols and speeds that are used.
RF just means something happens wirelessly using radio transmission - this should be completely transparent to the microcontroller, so it still depends on the protocol and speeds involved. So the "stress" (I assume you mean processor utilisation) will be the same either way.

For instance, you can buy a serial to bluetooth module that "looks like" a UART to a microcontroller, even though the data is actually sent using the BT protocol internally. At the "other side" (the receiving module) the data is output in UART fashion, so all the internal stuff is hidden, and you just have to worry about normal UART issues.

Even with a simple transparent link (no protocol, just transmission of levels), the Rx module just outputs exactly what the Tx input logic level is at, so it's effectively as if there was a wire connecting the two pins.

Depepnding on exactly what type of RF module you use, there may be some setting up and monitoring required, but that's not exclusive to RF.

EDIT - here are a couple of examples of the BT-UART modules:

Version with header

SMD Version - this is one I purchased (picture below), and am currently using in a prototype (running at 115200) with no problems. It is an HC-05 (useful to know when looking for datasheets)

SMD BT Module

As you can see, these modules have an onboard antenna, so all that is needed is power and signal connections.

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  • \$\begingroup\$ Thanks. Currently it is simple UART communication over USB. Also I meant processor utilization, thank you for the correct terminology- again I'm trying to teach myself EE as a mech major who hates mech... I was thinking of using Zigbee but have read here: electronics.stackexchange.com/questions/5314/… that digimesh may be better? I'm looking for as cheap as possible though, so I haven't found one way or another to be particularly better just yet. \$\endgroup\$ Sep 27, 2012 at 1:57
  • \$\begingroup\$ You need to decide how fast your data rates need to be, how many nodes will be involved, whether you want error checking, what transmission frequency, etc before you look for a module. Something like ZigBee sounds like it might be a good fit, and is very capable if you want to expand things later. If it's a very simple link you need, a serial to BT module as mentioned above can be bought for ~£5 (~$8?) on eBay, the downside is usually lack of decent (or no) documentation on the sellers page, but there are plenty of examples out there for certain modules... \$\endgroup\$
    – Oli Glaser
    Sep 27, 2012 at 2:23
  • \$\begingroup\$ ...and the documentation does exist, it's just a question of finding it. Most of them use a simple AT command set, but if you can use it at the default speed there is no need to set it up, just plug in and use. \$\endgroup\$
    – Oli Glaser
    Sep 27, 2012 at 2:25
  • \$\begingroup\$ Well I do plan on eventually expanding to many communicating with each other for experiment, and seeing how far I can have them and if I can set up a mesh network- which is why I thought zigbee or Xbee digimesh. The problem is those are ~$17US for the cheapest ones. Does the serial to BT module require any external electronic design/antenna work? The other nice thing about the zigbee/xbee is the integrated pcb antenna for me as well as fairly little work needing to be done as far as circuit design to hook it up. \$\endgroup\$ Sep 27, 2012 at 2:27
  • \$\begingroup\$ edit to last comment: I see your second comment about plug in and use- thanks for the info! \$\endgroup\$ Sep 27, 2012 at 2:28

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