LoRa Discovery Kit

[Tesla DeLorean]

Posted on April 05, 2017 at 22:40

LoRa Discovery Kit

STM32L072 and LoRa Discovery Kit featuring Open LoRa module by Murata using STM32L072CZY6TR MCU

http://www.st.com/en/evaluation-tools/b-l072z-lrwan1.html

Features

• Ultra-low-power STM32L0 Series MCUhttp://www.mouser.com/stm32l0, Cortex® -M0+ based with 192Kbytes of Flash memory, 20Kbytes of RAM, 6Kbytes of EEPROM, LCD, crystal-less USB, T-RNG, PCROP
• 157dB maximum link budget
• +20dBm, 100mW constant RF output versus Vsupply
• +14dBm high efficiency PA
• Programmable bit rate up to 300kbps
• High sensitivity: down to -137dBm
• Bullet-proof front end: IIP3 = -12.5dBm
• 89dB blocking immunity
• Low RX current of 10mA, 200nA register retention
• Fully integrated synthesizer with a resolution of 61Hz
• FSK, GFSK, MSK, GMSK, LoRa™ and OOK modulations
• Built-in bit synchronizer for clock recovery
• Sync word recognition
• Preamble detection
• 127dB+ dynamic range RSSI
• Built-in temperature sensor and low battery indicator 1.65V to 3.6V power supply

The AT_Slave example (creates AT modem via ST-LINK VCP) is about 41KB in size

• Attached is original shipping firmware (April 2017) Ping-Pong Demo
• Added LoraDisco_ATSlave_US915.hex a build of the example from the Cube Extensions, USA 915 MHz option selected
• Added LoraDisco_ATSlave_US915_V111.hex a build from the V1.1.1 tree
• Added LoraDisco_ATSlave_US915HYBRID_V111.hex
• a build from the V1.1.1 tree w/US915_HYBRID (17-Aug-2017)
• Added LoraDisco_ATSlave_US915HYBRID_FULL_NOT_TINY_V111.hex.zip a build using Keil native sscanf/printf w/AT+SEND fixed

[Andrew Neil]

Posted on February 21, 2018 at 13:36

tomkins.richard wrote:

a 915 MHz LoRaGo Port,

You mean this:

https://sandboxelectronics.com/?product=lorago-port-multi-channel-lorawan-gateway

?

[Tesla DeLorean]

Posted on February 21, 2018 at 13:56

Looks interesting, but I can't for the life of me understand why the 1PPS isn't just pushed across the pin header, and everyone seems to copy this UFL-to-UFL stupidity.

Keep hearing rumors of an SX1301 shield that runs off a NUCLEO/DISCO board. If someone has one, drop me a line.

[Andrew Neil]

Posted on February 21, 2018 at 13:59

Clive One wrote:

Keep hearing rumors of an SX1301 shield that runs off a NUCLEO/DISCO board. If someone has one, drop me a line.

Yes - that would be interesting!

[richard239955_stm1]

Posted on February 21, 2018 at 16:22

Yes, that's the kit. Complete and fits together well. We had to modify the TTN install for SPI to make it work properly with the Semtech software. Apparently, the TTN folks are diverging to a new packet forwarder and no longer support their current offering.

[richard239955_stm1]

Posted on February 21, 2018 at 16:25

I suspect the 1PPS coax is an element from the reference design everyone uses, thus 'why engineer a different solution?'

I agree, why not go through the connector, and why not just ***** ** to the Raspberry Pi 3 directly, why the HAT?

[richard239955_stm1]

Posted on February 21, 2018 at 16:26

Thank you for the guidance, will do that shortly and hopefully meet with success.

[Tesla DeLorean]

Posted on February 25, 2018 at 01:06

I know on the GPS modules I built for a decade we pushed the CMOS 1PPS out a pin connector, but yes I think we have some risk adverse engineers out there who would rather faithly copy a reference design than actually step back and reassess the design decisions with a broader insight. Over a couple inches of traces and into a minimally capacitive loadcompared to the coax and four connectors, I can't see itproviding any benefit at all.

This is probably also why going directly to a HAT or Shield seems to be avoided, now admittedly there are some FCC/emissions concerns here, but from maker/hobby perspective this drops into a different category. I think someone with some reasonable RF/PCB experience could do a better job at shrinking the circuit and putting GNSS on the backside behind a couple of power planes. Looking at the SX1301/1308 references I'd definitely think this could be fitted onto a RPi Hat.

I think someone had a design on a PCIe card

[algis]

Posted on March 26, 2018 at 12:54

Hello Clive,

I am testing this B-L072Z with STM32CubeExpansion_LRWAN_V1.1.4 and I want to check the bandwidth for tests. However if I turn on the continuous wave mode I get very narrow signal with the BW of ~10kHz (way smaller than 0BW - 125kHz). Can you help with this? It is very frustrating as if I send some packets they seem to cover bigger BW I would say close to 125kHz, but in CW mode it changes. I saw that there are LowDatarateOptimize options, but eve if I set to 0x00 the device do not work properly.

[richard239955_stm1]

Posted on March 26, 2018 at 14:48

Update:

I am placing an update here, for those that may be interested.

We have,

• two

  http://www.st.com/en/evaluation-tools/b-l072z-lrwan1.html

• running

  http://www.st.com/content/st_com/en/products/embedded-software/mcus-embedded-software/stm32-embedded-software/stm32cube-expansion-packages/i-cube-lrwan.html

  , V1.1.4,
• and joining a LoRaWAN using OTAA
• through a

  https://sandboxelectronics.com/?product=lorago-port-multi-channel-lorawan-gateway

  running at 915 MHz, Hybrid mode, on a

  https://www.raspberrypi.org/products/raspberry-pi-3-model-b/

• running

  https://github.com/Lora-net

• and connecting with a

  https://www.loraserver.io/

  .

The documentation widely available all over the internet is predominantly applicable to Europe and is in many places not usable in Canada and at times can lead you down the rabbit hole, the wrong way. There are shortcomings in the documentation on the internet and at times, obvious omissions as big as a barn door.

Some folks are very kind to respond with good knowledge when questions are posed in various forums, this STM Community Forum included, and in other forums people will either ignore you outright, ask rhetorical questions, or guess at answers that invariably end up misleading you (rabbit holes).

Overall, we have developed a great deal of knowledge about this technology and how we can make use of it.

We are a long stretch away from having an intimate understanding of this technology.

I see a need to build a much better antenna for our gateway

[richard239955_stm1]

Posted on March 26, 2018 at 15:05

Hello Krupta,

As my RF knowledge is mid 70's vintage, my ability to directly respond to your question is very poor.

That being said, have you got a copy of LoRaWAN-Regional-Parameters-v1.1rA.PDF?

If not, go to the LoRa Alliance webpage, get the contact information and submit a request for the LoRa specifications.

If you go through the issues, both open and closed, at this location,

https://github.com/Lora-net/LoRaMac-node

, I suspect that you're going to come close to an answer. The LRWAN Cube code is based on this Semtech code, and you're question pertains more to the radio operation that it does to the resources provided by STM. The Semtech website also has a Community Forum which helped us out with some questions.

Cheers, rtt