Let's Make Robots!

Not a smart way to connect Easy Radio modules!

ER900TRS: An extremely smart little module.

You just give it some volts, and a serial string, and it transmits it over air to another ER900TRS. This one can be pretty-pretty far away if you have an antennae - and it willoutput the serial string.

It cannot be more easy to communicate ASCII from one microcontroller to another!

But they are quite expansive, and so I thought instead of usin a new one for each project, I would make some sort of hook-up-system with old IDE-PC-cables..



Idea was that I should just solder the cable, and then insert the module when needed here and there..

This is not a good idea.

Darn thing does not connect very well that way, and so I spend hours and hours bugtracking on the dumb strings that did not come in right :D

Liiiitle looose connections, all the time.



This is how to do it:




I found out that one can just de-solder the pins rom the module, and add some wire. Stick some ffemale headers to the wire, and you are go to insert radio-transmission in 2 minutes on any standard project board :)


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Thanks for the tip, Im working with this modules, but I have a problem, I can't measure RSSI. I was wondering if you could give me some tip to test the Recieved Signal Strenght. Thanks for reading!

Hi Alseides,

The reason for my interest in the ER modules was in fact the RSSI:

I wnated to build robots that I could "remote" this way:

* Come to me

* drive away from me

apart from that, they should be autonomous. Also i could use this to make 2 robots chase each other etc.

What I found was that the ER-modules are a fantastic tool.. But the RSSI is just a blurry, messy signal not suitable for anything than testing different areals / antennaes on long distances, optimising for long distance etc. And hardly that, as a matter of fact.

So.. If you had the same thoughts, we are two who are still searching for a way to easily and simply approxymate distance to another circuit.

But - what are your problem excactly, I am just going on about my own life here ;)

/ Frits 

Hi Yoppy,

Your english is better than mine ;) - And I do understand your questions. However, it would take me half a day to come up with an answer, and that is simply too much - I have my own stuff to try to build.

I am happy to answer questions regarding things I have made, and made instructions on, but here we are talking third party, and I can only hope someone else is just working with these modules, are into them right now, and will answer you - I am somewhere else right now, sorry ;)

Best of luck, perhaps you should ask in the forum, make a new topic, and wait for someone to answer. This post is really just about the not-smart way of connecting..

/ Fritsl

i found this way for connecting stuff and i believe it is suitable for others components, sensors.....      :)

this example shows a handmade connector for SRF505
Sensor Pins -> Female Headers -> Wires -> Male Headers -> Microcontroller


can you show it in detail where to put each wire where.

You can look at the pictures, as I will not have time to make new ones.

From then it is quite simple (I do not have manuals either, so I can only give you from my memory):

V to V

G to G

One output directly from the Picaxe to the serial / signal IN on the ER (Not through a darlington, straight from the picaxe)

One from EA signal out to any digital picaxe in


THis is all you need for a basic send / recieve setup.

Have lots of patience, and possibly experiemtn with LCD's, to learn about serial in / out.

Always, if just starting, start out with having 2 picaxes talk to each other, through wires connected. Make that work, and then insert the EA instead of wires..

I am sorry, but I don't understand the question?
I was hoping to buy 4 of these and mount 3 on my robot with directionally shielded antenna's so that it could pick up a heading or at least determine which of the heat signatures found by my thermal array was holding the transmitter. You mentioned that it is bad for estimating distance to a subject but if they were used in triangle do you think it possible with metal shielding that they could provide a rough heading?
No, I do not think so, but I may be wrong.