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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i have seen your little 8R robot and i want to make it but their was only remote problem i want to just see inside the remote which you made for little8R thats all

But which part are you interested in?

This is old work, there are better options today :)

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.
IMG_6156.jpg IMG_6154.jpg
I am sorry, but I don't understand the question?
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 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


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