Single-Board Universal Module

Moss: Thanks for the links. I wanted the 3G module when I got my RFExplorer, but they couldn't be had at that time. I've ordered one now.

I am confident in the code, since (a) i can see the LNA_PA pin toggling which only happens during transmission, and (b) the same code works fine on the 1st 2 modules I built. Since the circuit hasn't changed, the problem is very likely on the physical side.

mpicpu: That is just an NRF module. the description is just generic for all the different modules, it dos notmean that the module you listed can actually support all those models.

I've checked both the U.FL as well as right at the NRF output. I'm comparing it to a working module, so I know where I should see a signal and don't. And yes, I have a test app that runs a specific frequency through a specific chip. I'm not too concerned about this since I know the circuit functions properly. I'd just like to get this module functional since (a) they're pretty expensive, and (b) I have a bunch of transmitters I'd like to install them in.

I got my upgrade board for my RF Explorer today. Easy enough to install. I probably won't get to checking out my NRF chip with it tonight though The stock 2.4GHz board just uses a CC2500 to capture the signal. We already had something similar for the CYRF chip, but I guess the key is having it calibrated so you know what the actual (rather than relative) signal strength is. The new board is much wider band should meet all my needs unless I go 5.8GHz some day.

Here is the 0.9.4 board which I am planning to order. Assuming the DC/DC works well, this could be the final iteration:
oshpark.com/shared_projects/PNfiUaYx

teardrops.ulp makes a mess of the board, trying to do hem 1-by-1 would be really tedious, and I haven'y had an issues with the 3 prior iterations I ran through Oshpark. I decided not to re-layout the board to separate the inductors, I don't think there will be much coupling with them 90-degrees, and if there is, I'll switch to a shielded inductor.. I haven't had a chance to play with the NRF chip yet.

Thanks for all the help you, Fernandez, moss, and SadSack provided. I really value the experience you guys have, and I think the board design is much better because of it.

I've been thinking about this some more, and I may have a way by which I'd feel comfortable selling these. If I remove the serial capabilities of the module, it becomes a smart-switch with 4 RF chips. My reading of the FCC rules indicates that this would be considered a sub-assembly and would not require FCC licensing. Of course that means you would need a 2nd board to do PPM->SPI (which would have all the protocol logic in it), which would drive up the cost for non-devo users. It also means another redesign of this board. However, it would also reduce the cost of this board somewhat as we could use a simpler power solution (I'd still keep the DC/DC converter on-board and probably add an output pin so the board can serve as a 3.3V supply). I'd remove the PPM, bluetooth, and USB connectors (USB would still have a header to allow for programming, but since reprogramming would be uncommon, we don't need an expensive mini-usb connector).

Having a 2nd board for PPM->SPI would mean we now have more space, for other functionality too on the daughter board.

Right, the impact for Walkera radios would be negligible (the module already functions as a MultiMod 2.0 for Devo tranmitters). It is the PPM folks who would need a separate board. this is really a backup though. I'm going to investigate getting the current boards built 1st.

I've been thinking about whether the bluetooth module can be used when mounted in a Walker radio. It will require careful timing as we'll need to multiplex the info messages with the protocol data on the SPI bus. That wouldn't be so hard, but we need to make it work with all protocols, each of which has different timings. I won't remove the bluetooth if there is any chance we can get it working. Talking with SadSack, an alternative to bluetooth is WiFi. The ESP8266 wifi chip works a lot like a bluetooth board but can be had in a 10mmx10mm board, and is much cheaper at only ~$3. I've done some initial experimentation with these, and one benefit is that it will reliably work with all Smartphones (the bluetooth solution I have now requires a $15 module to work with iPhone and is still untested). The downside is that it may be tricky to setup since we need to run the ESP8266 in AP mode. For testing, it can connect using the bluetooth pins so I can play with it with the existing boards.

The HC-05 is fine for Android, but i think you need BTLE for iPhone, and they are more pricey (HC-11 and HC-12 I think). Anyhow, one thing at a time.