Author Topic: radio breakout board not working in my setup  (Read 2072 times)

travmaga

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radio breakout board not working in my setup
« on: March 31, 2014, 05:07:30 PM »
Hi guys,
I'm just starting out on doing some research on which radio might work best for my project, and decided to get some breakout boards for the radios (rfm69's and 12's of all flavors) solder them up and then swap in and out as needed for testing in the environments.  well, i ordered some breakout boards from OSH Park
(http://oshpark.com/shared_projects/kcVjN7cA)
and soldered the radio's to them (the picture shows a rfm12b 915mhz) and plugged it into the breadboard, have triple checked all the wiring against the info associated with the radio and arduino hookups,
(http://openenergymonitor.org/emon/sites/default/files/connections.png)

 have made sure to use the 3.3v so no resistors are needed (at least as far as i can tell) and have tried running the basic send/receive sketch from the library here:

https://github.com/LowPowerLab/RFM12B

so they upload and compile properly, i change the setting in the sketch to be set for 915, and i can get the serial monitor to read out that it's sending, but the receiver doesn't seem to send the ack, so the sender won't continue to send, adn it pretty much stalls out there. 

i've tried switching the programs on the two setups i have (identical) so the sender acts as the receiver and vice versa, but they both respond in the same way as mentioned above.  If anyone might ahve any insight into how best to troubleshoot this, i'd appreciate the perspective.  i'm at the limit of my knowledge and have tried everything i know how to do- i'm guessing that i might need some additional hardware, as all the breakout boards i see on the other sites seem to have resistors and things such as that (showing my ignorance of hardware here) plugged into the boards, and i have none.  but the 3.3 volt interpretation of the sketch doesn't seem to call for them, so i'm not sure what's going on.  anyhow, i'll post the picture below so you can see my rig and thanks for your help, i'll answer any questions if there's more details you need to troubleshoot.  thanks a million guys and gals. 
-travis

Felix

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Re: radio breakout board not working in my setup
« Reply #1 on: April 01, 2014, 08:38:14 AM »
have made sure to use the 3.3v so no resistors are needed (at least as far as i can tell) and have tried running the basic send/receive sketch from the library here:

You will need level translation on the data pins going into the RFM radios, otherwise you will toast them.
Doesn't look like your board or your setup has them. So your radio might already be toast  :-\

travmaga

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Re: radio breakout board not working in my setup
« Reply #2 on: April 05, 2014, 04:25:20 PM »
Felix-
this makes a lot of sense.  I've been doing some reading in the direction you offered and i can see the problem now, the voltage to and from the radio (3.3) doesn't match the pin out (of 5v) as mentioned in this page-
http://www.airspayce.com/mikem/arduino/RF69/
If I may i proceed to ask another relatively simple question, just so I can do it correctly the first time- seems to me i would need to convert the voltage both ways (from the radio at 3.3 up to 5 ffor the digital pin to read, and 5v from the pin down to 3.3 in order not to fry the radio (again))
OR
 will the 3.3 from the radio be enough for the digital pin on the arduino to read?  my primitive understanding has me leaning towards the former, but i've been mistaken (read: learning!) so many times, i don't so much trust my intuition anymore.  if one of the benevolent learned types out there might once again throw me a bone on this next question, i sure would apprecaite it.  This stuff is so cool, i'm really looking forward to gaining a better understanding, and (hopefully) passing along my knowledge as well someday.  thanks again for the help-
travis

Felix

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Re: radio breakout board not working in my setup
« Reply #3 on: April 06, 2014, 08:36:46 PM »
Typically you don't need it both ways. In a 3.3V to 5V system, a logic high will be around 3V so 3.3V should be plenty to be picked up by the 5V as a "1". Read the datasheet of the specific target MCU for the accurate threshold. To convert upward you will need a FET instead of a resistor voltage divider. But I've never had to do that when going from 3.3V to 5V.

BR549

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Re: radio breakout board not working in my setup
« Reply #4 on: April 08, 2014, 11:50:28 PM »
uChip has some good breakout boards on OSHPARK for the non "C" parts (RFM69W & RFM69HW) that already have the voltage dividers:

https://github.com/uChip/RFM69W_BOB   
http://oshpark.com/shared_projects/bJRprI06

The module price is about the same, but If you already have enough modules you can see his schematic for a working design.

travmaga

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Re: radio breakout board not working in my setup
« Reply #5 on: April 28, 2014, 07:18:11 PM »
br549, felix,
thanks so much for your input.  really appreciate it. it was good advice and have been sending wireless data for a good while now.  these things are so cool!