Developing with LoRa

[Dajgoro]

Hi.

I'm looking into LoRa and there are some things troubling me.
All google searches about LoRa end up with arduino.
LoRa modules cost 2$ on ebay but I can't find the same modules from proper vendors like mouser.
The only non arduino project that I found is for the STM32F103 with the SX1278.
The bom of the two IC is over 6€ which is a bit too high comparing against ebay prices.

What modules/mcu are used to develop low power/low cost devices with LoRa that don't include arduinos?

[cgroen]

Murata makes a module

[Dajgoro]

Muratas module is still 8,81€ in volume, which is a bit expensive.

[JimRemington]

The SPI control protocol for the LoRa modules is well documented, so any MCU should work with it.

Why not just buy the SX127x chips in quantity from Semtech, and get on with the project?
https://www.semtech.com/products/wireless-rf/lora-transceivers

[Dajgoro]

Implementing my libraries from scratch might take too long, I'm trying to see if there is a way to make a proof of concept without doing all that and achieving low power consumption.
So far I found that I could buy a STM32 devboard and attach a SX1278 to it and try out the stm32 libraries.

[Radiohead]

Hello Dajgoro,

What are you trying to build? Are you experimenting for hobby interests or are you considering using LoRa(WAN) for a product that will be available on the market? Or are you only interested in using the LoRa modulation method and use your own message protocol or do you want to use the LoRaWAN protocol? Which network will you use? The Things Network, your own network, or any local providers? What are your restrictions?

For hobby projects or products you want to include LoRaWAN without much hassle, you could use a complete certified module like those from Microchip, Murata, etc.. When you include them you can have your product certified by similarity, which cost a fraction of having your own LoRaWAN firmware stack tested. Depending on your local regulation or the network provider (if you don't build your own network) you would still need to do radio performance tests to check if you didn't botch the antenna design and your radio performance is acceptable to the network providers standards. Most certified modules will only require a few IO and a communication interface like a UART to get LoRaWAN going, but they cost more and are often not the smallest in terms of PCB area.

You could also only use the SX127x chips from Semtech and build the reference design yourself, but I would only advise this if you're planning to sell in the thousands of units anually. Another option would be modules with only the SX127x chip like the RFM95/96 from hopeRF. These modules are not LoRaWAN certified, since they are only the LoRa Tranceivers with the reference filter and output stage design, but lack the integrated microcontroller and require an external microcontroller with firmware to control it. You could hook it up to your own MCU of choice and write your own LoRaWAN firmware. Semtech has it's own github with code for LoRaWAN nodes and the packetforwarder for LoRaWAN gateways available: https://github.com/Lora-net You could port this to your own MCU of choice, altough certification by similarity won't be possible when you change the microcontroller from the one used in the certified design.

Muratas module is still 8,81€ in volume, which is a bit expensive.

LoRa modules cost 2$ on ebay but I can't find the same modules from proper vendors like mouser.

Mouser, Farnell, Digi-key or etc. will never be as cheap as Ebay. But with Ebay you never know what has happend between you and the manufacturer of the module or whether all the modules work as expected. The company I work for uses the modules from HopeRF (directly from HopeRF, not from Ebay) and we never had any problems with them, expect of our customers applying 12V to them directly , not removing the conductive foam from the modules or thinking it was a pre-certified module with RS485 capabilities out of the box . If you want to use these modules, go to a local distributor, as the prices for a single unit exceeds the price of a certified module on farnell, Digi-key, RS and etc.

[tpowell1830]

Hi.

I'm looking into LoRa and there are some things troubling me.
All google searches about LoRa end up with arduino.
LoRa modules cost 2$ on ebay but I can't find the same modules from proper vendors like mouser.
The only non arduino project that I found is for the STM32F103 with the SX1278.
The bom of the two IC is over 6€ which is a bit too high comparing against ebay prices.

What modules/mcu are used to develop low power/low cost devices with LoRa that don't include arduinos?

Marco Reps used a raspberry Pi with the MatchX device.

[Dajgoro]

Hello Dajgoro,

What are you trying to build? Are you experimenting for hobby interests or are you considering using LoRa(WAN) for a product that will be available on the market? Or are you only interested in using the LoRa modulation method and use your own message protocol or do you want to use the LoRaWAN protocol? Which network will you use? The Things Network, your own network, or any local providers? What are your restrictions?

For hobby projects or products you want to include LoRaWAN without much hassle, you could use a complete certified module like those from Microchip, Murata, etc.. When you include them you can have your product certified by similarity, which cost a fraction of having your own LoRaWAN firmware stack tested. Depending on your local regulation or the network provider (if you don't build your own network) you would still need to do radio performance tests to check if you didn't botch the antenna design and your radio performance is acceptable to the network providers standards. Most certified modules will only require a few IO and a communication interface like a UART to get LoRaWAN going, but they cost more and are often not the smallest in terms of PCB area.

You could also only use the SX127x chips from Semtech and build the reference design yourself, but I would only advise this if you're planning to sell in the thousands of units anually. Another option would be modules with only the SX127x chip like the RFM95/96 from hopeRF. These modules are not LoRaWAN certified, since they are only the LoRa Tranceivers with the reference filter and output stage design, but lack the integrated microcontroller and require an external microcontroller with firmware to control it. You could hook it up to your own MCU of choice and write your own LoRaWAN firmware. Semtech has it's own github with code for LoRaWAN nodes and the packetforwarder for LoRaWAN gateways available: https://github.com/Lora-net You could port this to your own MCU of choice, altough certification by similarity won't be possible when you change the microcontroller from the one used in the certified design.

Muratas module is still 8,81€ in volume, which is a bit expensive.

LoRa modules cost 2$ on ebay but I can't find the same modules from proper vendors like mouser.

Mouser, Farnell, Digi-key or etc. will never be as cheap as Ebay. But with Ebay you never know what has happend between you and the manufacturer of the module or whether all the modules work as expected. The company I work for uses the modules from HopeRF (directly from HopeRF, not from Ebay) and we never had any problems with them, expect of our customers applying 12V to them directly , not removing the conductive foam from the modules or thinking it was a pre-certified module with RS485 capabilities out of the box . If you want to use these modules, go to a local distributor, as the prices for a single unit exceeds the price of a certified module on farnell, Digi-key, RS and etc.

Well, I do hardware design for a living, and recently people started asking me for things that might require LoRa so I started looking into it.
I was told that the cheap ebay modules have iffy specs as you mentioned, so that makes them a big no for developing any sort of product.
So it turns out there is no way of cheaping out with lora, the only proper way seems to be using proper devices such as the Murata module or mcp module.
I'm also looking into how much development time it takes, if somebody asks me how long would it take to make something, I'm still not sure what to say.
I'll have to get devkits and see how good/bad the firmware situation is.

[bingo600]

RFM95W  (868Mhz) ($4) is a neat lora module from HOPE (licensed from Semtech) & compatible w their commands.

/Bingo