LowPowerLab Forum

Hardware support => RF - Range - Antennas - RFM69 library => Topic started by: sunspot on September 14, 2013, 09:50:59 AM

Title: SX1231(H) versus RFM69W(HW)
Post by: sunspot on September 14, 2013, 09:50:59 AM

I recently ordered and received a pair of R3 (RFM69HW) moteinos, which work great. Congratulations on all of the great work done on them.

However, in thinking about their design, I wonder why you chose to go with the Hope RF modules as opposed to just using the Semtech SX1231(H) transceiver ICs that they are based on? The Hope RF modules look like they are just a PCB with the Semtech IC and a handful of simple passive components, presumably not very different (if at all) from the reference designs available on Semtech's website.

The potential advantages I could see for using the Semtech IC directly include:
- lower cost: best prices I've seen are $2.28/$2.01 for SX1231/SX1231H (Digikey, Qty 25) vs $4.50/$5.95 for RFM69W/RFM69HW (D6labs, Qty 1)
- better integration in board layout, resulting in potentially smaller board

Potential disadvantages appear to be:
- more assembly work required to mount the IC and passive components
- routing challenge for incorporating everything on a 2 layer board (mounting the Hope RF module onto a 2 layer board effectively results in a quasi-4 layer board)

For a prototype, the effort saved by the Hope RF modules is probably worth the small additional cost. But for a production run of many dozens of boards, it seems like the Semtech approach might be better. Are there other advantages/disadvantages for the two approaches that I've missed here?

Title: Re: SX1231(H) versus RFM69W(HW)
Post by: Felix on September 14, 2013, 09:03:00 PM
It makes little sense to make the modules myself, many more points of failure. The discretes are 0402, not something I look forward to making myself. If I ever buy a 100k PNP that can assemble them I might consider it, but until then, I think just outsourcing that part saves me a lot of headache. The volume prices are not bad at all. Plus Moteino can be used with/without the transceiver, or users can solder their own if they want to or buy them separate.