A while back I looked into using a SX1272 LoRa set of transcievers for a project and am finally getting around to ordering them. The Libelium web portal, dubbed "Cooking Hacks", sells them at about $50 in XBee format (here) whereas you could get one on an QFN IC for about $5 through Mouser (here). Why is the price difference so great? These are the exact same products except for the mounting form, right?
(PS: I am only interested in buying from Mouser instead because of bulk purchasing- I want to be able to have a updated stock count and I trust them more frankly)
Why is the price difference so great? These are the exact same products except for the mounting form, right?
One would appear to be a surface mounted chip , the other a module.
The module has all the required supporting components mounted on a circuit board that has been designed for you, and which uses a familiar pinout.
In order to use the bare chip, you would have to design a circuit board (you probably won't get good performance with general purpose breakouts because the RF section of the board, going to the antenna, is layout dependent) and have it manufactured, and then load the parts on it. That's a lot of work and know-how, plus the expense of having the board made.
That said, that module does look rather pricey!
As others pointed the Mouser part is the RF microcontroller only, you'll need to spend a bit more to build all the circuit it requires to work. More details you can find at the Semtech, like this design reference: Find Product Documentation
Also, High-Frequency design requires good quality components with tight tolerances, as well special care when drawing the PCB to avoid interference and minimize noise. Good quality crystal and high-frequency inductors are not as cheap as a SMD resistor... Finally, you can't simply built this sort of circuit on a breadboard and expect it to work.
Depending on the quantity you'll be requiring, let's say, over 100 or 200 units, might worth do your own design. Just don't forget to estimate hours designing, reading documentation, building prototypes, testing, PCB and PCBA, as well shipping for everything.
I imagine that Libelium also provides some software support to integrate the module into its existing lines of products. That's some value added as well. If you wish to do what they did and are not short of RF PCB and software design skills as well as time, you'll probably spend similar amount of money (counting your hours for PCB and software design).
Thanks all for the responses. I never considered the impact on performance using my own parts could have. I think I'll contact Libelium directly to see if they can provide bulk orders. I believe they supplied a couple thousand units to Beartooth (Peer to Peer offline mesh). That's my best bet unless someone can produce a different supplier or a better-stocked item.
Thanks again and regards.
You can buy LoRa SX127X ICs as modules complete with all the necessary support circuitry, around $10 in one of Qs..
Dorji DRF1278F, 0.05" pin spacing.
Such as the Hope RFM98, 2.0mm spacing.
See here for same examples, and how they are fitted to PCBs.
I have also just been testing some of my own MikroBus (Google it) LoRa modules, for an Arduino DUE based modular shield.
Module is DIY, but work out at less than £10.
They work fine.
Thanks for the advice, I'll look into those. I may end up just mass ordering those PCBs and saving a ton of money @srnet