Using a Logic Level Converter w RFM69 radio ??

[anthonys]

I have an Arduino Uno running 5v and have purchased the Bi-Directional Logic Level Converter (BD-LLC) convert the 5v to 3.3v for the RFM69HW (https://learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guide). I am still new at this electrical stuff and having difficulty in figuring out how to wire from the Arduino UNO R3 to the Level Converter to the RFM69.

Thanks

[papa]

Welcome, anthonys, we all start somewhere. I've never used a logic level converter. I've started this new thread that might draw more attention from others & I'll do my best to respond.

You are wise to protect your RFM69 radio from the Uno's 5 volts that would damage the radio. One must do more than connect the Uno's 3.3 volt pin to the RFM69's Vcc (power in). One must also protect the RFM69 from the 5 volts the Uno sends thru the digital pins like D2,D10-D13. For this I use a Buono Uno that can be switched to send only 3.3 volts thru those pins. Some people use logic level converters with a Uno.

For a Uno, I believe this Adafruit product might be a better option. In one package it supplies the RFM69 radio & the translation between 3.3 volts & 5 volts for ALL the RFM69 pins needed. The logic level converter board you referenced can only handle 4 pins so I believe you will need TWO LLC boards for each RFM69 radio.

As to using the LLC, I base my suggestions on this Sparkfun schematic.  As I see it ... connect the schematic's "high side" GND pin to the Uno's GND.  Connect the schematics "low side" GND to the RFM69 GND.  Connect Uno 3.3 volt pin directly to RFM69's VCC pin. For a digital pin connection needed between the Arduino & RFM69 (see forum schematics), connect the Arduino pin to one of the HV pins AND at the LOW side LV pin of the same channel connect the RFM69 pin indicated by a forum schematic.

For example ... in our forum's node schematics, RFM69 pin DI00 connects to Arduino D2.  So you might connect the Uno D2 pin to the LLC's HV1 pin AND then connect LLC's LV1 to RFM69's DIO0 pin.  The LLC's Channel 1 would then connect Arduino D2 to RFM69 DIO0 & as needed, translate the voltages between the Uno & the RFM69.  Do this with all Uno digital pins (like D2, D8, D10-D13) that a forum schematic connects to an RFM69.  Each LLC channel should provide a safe voltage translation bridge between an Uno & an RFM69 radio.

Again if you use an Arduino Uno (5 volts), I believe the Adafruit product would be a more compact, convenient option & save you some soldering.

Disclosure 1:  I've never received compensation from Adafruit.

Disclosure 2: I've never used the Adafruit RFM69 breakout board, but forum member greginkansas recommended it.  See also my comments in this post.

Experienced users of Logic Level Converters, what are your suggestions?

     

[anthonys]

Hi Papa, thanks for your quick response. I took your advice and just purchased 3 Adafruit RFM69HCW radios at 868 or 915 MHz. I like the fact it can do "Each radio comes with some header, a 3.3V voltage regulator and levelshifter that can handle 3-5V DC power and logic so you can use it with 3V or 5V devices." This will help me as a newbie to get things going.

I have all my parts ready. I actually purchased 3 Arduino Uno, that are not switchable, which I forgot about after I discovered the switchable one, which is coming from china and will use this one for my MQTT gateway along with the updated radio. I will use the other 2 for my nodes per your diagrams. I really got inspired by all this after reading UBER Home Automation Instructable by Erik Tsai, and I am really glad you continued the instructable for Openhab2, which I now have running with MQTT on my Pi version 2.

I just purchased a course on Udemy "Mastering MQTT" by Venkatesh Varadachari, (https://www.udemy.com/mastering-mqtt/learn/v4/overview) which has been a huge help to understand how the MQTT protocol works, as I think its the most important part.

Once again thanks for your help and I will keep you posted.  Regards Anthony in San Diego, CA

[anthonys]

I found this article for connecting a RFM69W to an Arduino Uno using a logic level converter:

www.faranux.com/product/rfm69w-868mhz-20dbm-hoperf-wireless-transceiver-mg19-rfm69w/

papa: Yes, that article has some useful information.  IMO, especially for beginners, using LLCs adds more complexity to an already difficult project.  Better to keep it simpler with a 3.3 volt Arduino like a Buono Uno, or the Adafruit RFM69 breakout board with a Uno, or a 3.3 volt Arduino with built in RFM69 radio (Anarduino Miniwireless or a Moteino).

[papa]

"Once again thanks for your help and I will keep you posted. Regards Anthony in San Diego, CA"

"the switchable one, which is coming from china"

     ^^ papa: I hope it's something like a Buono Uno which supplies more 3.3 volt current than some boards. The RFM69 radio, especially the "H" high power ones need a lot of current.

You are welcome, anthonys, good to hear from you.

[anthonys]

Yes the one from china has a switch on it for 3.3v to 5V, just taking forever to get here

papa: In my experience Buono Unos, those switchable Arduino compatibles work pretty well. Though, sometimes the switches can glitch on one side & the device gets no power (power LED does not light).  If that happens, nudge the switch a tiny bit away from the glitching side.

[greginkansas]

Once you get your sea legs with this stuff you can use the sparkfun logic level converters. I use them on my MEGA nodes.

papa: Yes, greg, that sounds like a good approach for anthonys:  For now, while beginning a complex project, try to use less parts that might need troubleshooting.  Then later with more experience, try the logic level converters with bare RFM69 radio & Arduino Uno.

Also, as you suggest, greg, one could build a many-function node on an 5 volt Arduino Mega by using logic level converters with bare RFM69 radio OR by using the Adafruit RFM69 breakout board.  One would need to use sensors, etc compatible with 5 volts or protect them with LLCs.  One would also need to avoid making the current demands more than the Mega could handle.

[anthonys]

Another question I have, since I now have 3 of the RFM69HW (3.3v) radio (http://www.hoperf.com/upload/rf/RFM69HW-V1.3.pdf), if I use these on some nodes, will they work with the gateway that will be using a the Adafruit RFM69HCW that you recommended (https://www.adafruit.com/product/3070).

Thanks

[papa]

The different RFM69s should communicate with each other as long you bought them with the same frequency AND in the sketches use the same frequency, encryption key, etc.

PS For the rest of this week, I may not be very available to answer questions.