MX-RM-5v radio transmitter & Receiver SERIOUS lack of resources. Plz Help.

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Digisapien

Member
Even with Chatgpt, gemini, etc, I cannot get any code to work. I have an 18m2, transmitter, receiver, Led, button. I just want to create a circuit that when the button is pushed the transmitter sends a signal to the receiver, and the led comes on. If anyone has any resources please send link. Thank You.
 
It would probably help if you post your test code.

In my experience, it can be difficult to align the frequencies of cheap Tx and Rx modules that don't have crystals.
 
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What range is intended? PICAXE & 433MHz data comms issues have been extensively discussed over the decades on this forum. BROWSE postings!

But your MX-RM modules (seemingly 2008 vintage?) are just cheapie resonator types that were obsolete even 20 years ago... Where do you live? I'd strongly recommend using decent crystal oscillator based ones (pictured)!

Note - even the 08M2 can handle infrared commands which are good for several metres range -you may not even need 433 MHz for simple use.
 

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manuka said:
What range is intended? PICAXE & 433MHz data comms issues have been extensively discussed over the decades on this forum. BROWSE postings!

But your MX-RM modules (seemingly 2008 vintage?) are just cheapie resonator types that were obsolete even 20 years ago... Where do you live? I'd strongly recommend using decent crystal oscillator based ones (pictured)!

Note - even the 08M2 can handle infrared commands which are good for several metres range -you may not even need 433 MHz for simple use.
Click to expand...
I have been going at this using part by part configurations and writing it in a book for my memory. I am now on this one. The trans/rec I am using may be outdated, and I definately am going to get your suggestion and try it, but MX-RM is a very widely available and easy to obtain part. I have already discovered a lot with this project. 1, it seems the rfout and rfin commands seem to be designed to work with a particular encoder chip, Serin and serout, after multiple tries will not communicate from a chip to itself, despite all of my reading, trial and errors. I have finally gotten SerIn and SerOut to work from 1 chip to another. Soon to try the two chip concept pairing with the trans/rec. I am using the picaxe development board for test. I do have one question though,... If my SerIn is connected to anything, even with a 10k pulldown, the program will not download as long as this wire is connected. What am I missing and or is this normal?
 
Normal. Using the standard 22k series resistor with the 10k to ground at it's input end provides 1) a 32k pulldown and 2) a 22k current limiting resistance for occasions where a true RS 232 cable is used (ranging from +/- 3v to +/- 15v input signalling). The chip has internal input protection diodes to help prevent voltages that are over the chip's Vdd supply (typically 3 to 5.5 volts) from damaging to input circuitry but current limiting is required (the 22k resistor).

Ok. If you have a pullup resistor between the SerIn pin and Vdd, it is likely to prevent the pin from being pulled low enough to result in a logical low ('zero') signal from the program cable being recognised as a logical 'zero' bit.

Conversely, with an added (say, 10k) pull down resistor, a logical high from a programming cable to only +5v (like the AXE027 and others) will appear accross the 22k + 10k pulldown resistor pair, which acts as a voltage divider. With a +5v logial 'one' coming from the programming cable and applied across the divider pair, this will result in about 1.55 volts being applied to the SerIn pin. This is unlikely to allow a logical high bit from the programmer to be recognised by the PICAXE as a 'one'.
 
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PLEASE post your PICAXE code, circuit layout & schematic for BOTH the receiver & transmitter.
Note: It may help to have a receiver monitoring your local 433 MHz activity. This band,although meant for very low power transmitters, may host other (POWERFUL) signals that can swamp your flea power transmitter.
 
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Good evening

For your information, I am in the process of finalising a similar project: transmission of an infra-red barrier to an electronic stopwatch used in Agility (dog sport), in 433 Mhz.
I've created a post on the French-speaking forum on the subject.

I had positive results with a test program up to 29m, today I tested a first version in real conditions with the stopwatch by placing the detection barriers at 22m (without trying to increase the distance).

At first I used the modules in the post, but in the end I bought a Velleman kit that impressed me (they claim a range of 30m and I'm almost there).
I'm using rfout and rfin on pines other than the programming ones, so there's some functional code that will have to be adapted (I've modified the timing following a few problems).

The transmitter is a Picaxe 18M2 and the receiver a 14M2, the first electronic diagram is also there.
If it helps Digisapien :)

NOTE : I placed the transmitter and receiver +/- the same height from the ground, which gives good results.

Translated with DeepL.com (free version)
 
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