Building gateway with MTAC-LORA-H 915

Gateways
1

Hi, I have successfully constructed a gateway with Raspberry Pi 3 and MTAC-LORA 915 (connection via USB to mPCI-e adapter) before. Due to the need to build more gateways, I needed more LoRa RF accessory cards and had to order MTAC-LORA-H 915 as MTAC-LORA 915 was at ‘end of life’.

The problem is that I am facing issues when using MTAC-LORA-H 915.
I am unable to run util_pkt_logger (from https://github.com/kersing/lora_gateway), as it returns the following errors:

ERROR CONNECTING CONCENTRATOR
ERROR: FAIL TO CONNECT BOARD
loragw_pkt_logger: ERROR: failed to start the concentrator

The same Raspberry Pi works fine when a MTAC-LORA accessory card is used instead. Could you please point me towards a solution?

Thank you.

2

Not 100% sure but I strongly suspect that will not work.

First read the incomplete discussion here: MTAC-915-H-LORA SPI vs USB

Next, while I can’t readily find a true data sheet, a picture of the board internals does not seem to show any USB interface chip. So likely it is an SPI-only design.

Further it is a v1.5 concentrator design, implying different software details as well.

Probably you need to connect it via SPI (if you are good at soldering you can tap signals off the base of your adapter’s socket) and build firmware suitable for a v1.5 design. A pi can support SPI so that’s probably best. but If you still really, really want USB concentrators you can get something like an RAK833, just be sure you buy the more expensive model with the optional USB chip.

2 Likes
3

I can confirm the -H model is SPI only and will not work with an USB adapter. The RAK833 is a suitable replacement, however make sure to order the version with USB enabled as there is a SPI only model as well.

Having said that, USB connections to the concentrator as previously used in the MTAC cards are no longer supported in the reference software and will be discontinued in my implementation as well. SPI is future proof (for now). Or hardware using the new USB interface reference design as used by some other vendors (not RAK and MultiTech)

1 Like
4

Thank you both for providing me with the solutions. If I may, I would like to ask some follow-up questions.

  1. Would a SPI to USB adapter (such as https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F181025572449) still not work for my purpose? If it does work, would I be able to use the util_pkt_logger implementation without having to change any lines of code?

  2. Would using a RAK833 (with USB support) be as simple as just plug-and-play, similar to MTAC-LORA 915? Or would some lines of code have to be changed?

  3. Are support for USB connection being discontinued due to limitations posed by USB connectivity (such as data loss/bottleneck)?

Thank you once again for sharing your knowledge.

5

Possibly, but it’s utterly inferior to using the pi’s native SPI. The only hard part of either project is connecting the SPI lines to the LoRa card, and you have to do that either way.

It should work if you find the branch old enough to have FT2232 support. IIRC you do need to deal with the reset. But even though most of my cards have USB, subsequent to one five minute test I’ve only ever used them in SPI mode. There’s no sound reason to use USB for this unless your host computer is something like a PC that does not support SPI. Your pi supports SPI, so you should use that.

Yes, latency to be specific.

1 Like
6

Thank you for the in-depth answers to each of my questions.

Yes, latency to be specific.

Learning from your posts, I am now convinced that conducting LoRaWAN experiments via USB concentrators would result in inferior amount/quality of data being collected (using Kersing’s implementations). In regards to the latency issues you have stated,

  1. How does this impact the LoRa packets being captured by the concentrator in reality?
  2. Are they more likely to result in CRC_BAD or some packets being missed during the capturing process?

Probably you need to connect it via SPI (if you are good at soldering you can tap signals off the base of your adapter’s socket) and build firmware suitable for a v1.5 design. A pi can support SPI so that’s probably best. but If you still really, really want USB concentrators you can get something like an RAK833, just be sure you buy the more expensive model with the optional USB chip.

I was insisting on a USB concentrator as I had no experience in soldering or Pi modifications. Hence, the USB concentrator was an easy process that I could follow and implement.

  1. Is there a tutorial on how the MTAC-LORA-H can be connected to the Pi via SPI?
  2. For building a firmware suitable for a v1.5 design, is that simply downloading an online-available firmware and installing it via Pi?

I apologise for these newbie questions. My google search results did not yield any straight-forward answers to the questions I had (due to my lack of skillset and understanding in this area).

7
  1. Less throughput and possible timing issues when sending data
  2. Not related to CRC, just missed packets
  3. I have not seen one, so Google is your friend
  4. You can use the same software configured for SPI in stead of USB.
1 Like
8

Thank you for the reply. I could not find one for SPI on your Github repository (my sincere apologies if I missed them), but would this be what you were referring to?

global_conf.json.MTAC-LORA-H-915.basic

9

That is runtime configuration, for SPI support you need to compile the LoRaWAN libraries with SPI setting.

10

Does the build not also need to be specific for a v1.5 concentrator hardware configuration (ie, FPGA, etc)?

11

The library should take care of that, it queries (runtime) the fpga code version.

12

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.