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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Mukund22kar's picture

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

fritsl's picture

But which part are you interested in?

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

TheGrue's picture
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?
fritsl's picture
No, I do not think so, but I may be wrong.
Mukund22kar's picture
IMG_6156.jpg IMG_6154.jpg
fritsl's picture
I am sorry, but I don't understand the question?
Mukund22kar's picture
can you show it in detail where to put each wire where.
fritsl's picture

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..

guibot's picture

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


probably you just need to add some filter caps.