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• Sample distribution plans (and a bounty?)

  Sensors • 12/06/2020 at 13:23 • 0 comments

  Hello! I realise it has (somehow) been two months since I last picked up this project, so apologies for letting it stagnate like that. I hit a bit of a busy period with work so unfortunately my personal projects took a bit of a back seat. But not to worry, time to get moving forward again!

  I've come to a decision with how to distribute samples for people who have expressed interest. As mentioned previously I was worried about sending these off into the wild and never hearing about them again... they were not cheap to have made at a volume of 10. I don't want to be massively out of pocket, but more importantly I really want anyone who gets their hands on one to have an incentive to make something cool and of community value.

  So here's my plan at the moment;

  • Make 6 or 7 modules available for purchase at cost price, one module per person
  • Offer refunds to those who create something of community value within a set time period

  What I would consider 'something of community value' would be a project that others can learn from, snippets of code or example firmware that will help others get started, or, the holy grail in my mind, an open source library for the part. Additionally, to qualify for a refund all outputs from working with module must be open source/publicly available.

  I am also considering putting a small, additional bounty on the open source library, because that's what will make this most accessible to the community! 
  

  The finer details of all of this still need worked out, but I'm hoping to get this process kicked off in the next week. If you have filled in the survey and expressed an interest in helping out with development you'll be among first to be contacted about acquiring a module.

  As always, if anyone has any thoughts I'd love to hear them.

• The prototypes have arrived!

  Sensors • 10/01/2020 at 11:39 • 2 comments

  After some issues with back-ordered parts I got the samples from the manufacturer last week... Only a month later than planned. I had 10 samples made in total, so now I've got to solder some onto the break-out boards and get them tested! 

  At this point I haven't had RF shields made, but I don't think EMI will be an issue regardless. 
  

  I'm still trying to figure out how to get a few of these into the hands of people who are willing to write some libraries and test them. Given the cost of them at this low volume I don't want to just send them all out to never hear about them again so I need to find a way to encourage people to see any testing through. Suggestions welcome.

  If you're interested in participating in writing firmware libraries and testing the modules, I'd again encourage you to fill out the survey since I'll be using details collected in that when it comes to offering up units for test.

• Break-out boards & Prototype order update

  Sensors • 08/20/2020 at 11:44 • 0 comments

  Over the past week I've received the PCBs and components for the ORV1110A break-out board (photos below).

  I had originally ordered these to coincide with delivery of the prototypes ORV1110A assemblies that I have ordered, but unfortunately due to a shortage of one particular TCXO there has been a delay in assembly. Hopefully that will be resolved soon and I'll have the prototypes in hand in a couple more weeks.

• Ordering prototypes & firmware development

  Sensors • 07/14/2020 at 12:11 • 0 comments

  I've noticed that a few distributors now have a date for when they will have stock of the LR1110 (22nd July), which means it's time for me to get assembly of the first prototypes underway. Alongside that I'll have some breakout boards manufactured to make testing easier. I estimate that I'll have assembled units in hand by mid-August.

  I may fund this first batch myself rather than do something like crowdfunding. It ain't gonna be a cheap production run, but the module is still untested so I wouldn't feel comfortable selling it as a 'finished product' to anyone at the moment. I'd like to hear people's thoughts on this.

  Firmware/Library development

  It's likely my time to work on the firmware for the module is going to become more restricted, so I'd like to get the modules into the hands of people who are wanting to create open source libraries for arduino, etc.

  If you're interested in helping with the firmware development for the module please express your interest in the survey.

• Mechanical Drawings

  Sensors • 07/02/2020 at 13:01 • 0 comments

  I've just finished the mechanical drawings and pad layout for the datasheet

  (All units are in mm)

  You'll notice the height is 2.8mm rather than the planned 2.5mm. That's just because of the 1mm PCB for the first revision to make manufacture easier, but I'll likely move to 0.5mm thickness PCB if I can for a total height of 2.3mm!

• Finalised Break-out board

  Sensors • 07/01/2020 at 13:54 • 0 comments

  As I previously mentioned I had a concern about the existing break-out board design, especially if it were to be made available as a self-soldered kit since the u.Fl connectors and 0402 passives of the tuning networks can be difficult to solder. 

  I'm pleased with the solution I settled upon which has two main updates:

  1. Removed the antenna tuning networks:  Without these the RF performance might not be ideal, but there are far too many variables involved at the prototyping stage to properly tune 3 antennae anyway, especially for LoRaWAN with various regional frequencies.
  2. Supports u.Fl and SMA connectors: This should give people the option to avoid soldering the fiddly u.FL connectors if they want to.

  I've done my best to ensure the feed lines for the antennae are 50 ohm matched, but they're so short anyway the losses if unmatched will be negligible. I would have liked to support the two connector types simultaneously, but I can't think of how to achieve that without creating a stubthat would degrade RF performance.

  The SMA connectors are pretty bulky, so if this is used on a breadboard it'd have to be placed at one end to give enough clearance below.

  With u.FL connectors populated:

  With SMA connectors populated:

  And of course, all connections are labelled on the bottom:
  

• Semtech official LR1110 DevKit ain't cheap!

  Sensors • 06/16/2020 at 10:50 • 0 comments

  I've been keeping my eyes peeled for any indication of how much the dev kit for the LR1110 is going to cost, and recently a new product listing popped up on Symmetry Electronics....

  A product titled "LR1110 DVK @915MHZ FOR NORTH AMERICA" is showing up for $199.99. Not much product detail, but I think it's safe to assume this is the NA regional development kit.

  I'd like to hear what everyone else thinks, but in my book that's prohibitively expensive for hackers and hobbyists. It's just another reason to push forward with this project to make the part more accessible and affordable for all!

• A design review with Semtech

  Sensors • 06/16/2020 at 10:25 • 0 comments

  The  engineers over at Semtech were kind enough to carry out a PCB design review of the module. The feedback was positive overall, but pointed out a few areas I could modify to improve performance.

  The key points:

  • Use a TCXO instead of regular crystal oscillator as my 32MHz reference. This improves GNSS performance for portable devices where temperature compensation may be more important.
  • Improve RF isolation between RF Power Amplifier pin and Sub-GHz RF output pin
  • Spread out RF switch and RF power traces to reduce crosstalk
  • Remove a few unnecessary test points

  I'm pretty happy with the feedback I got on the design, the next step is to get this built once I get my hands on the LR1110!

• Breakout board - A first pass

  Sensors • 05/12/2020 at 13:10 • 0 comments

  For people to tinker with this module prior to using it on a custom PCB I wanted to create a break-out board/development kit. This is my first pass at it, but I think there are some changes that I think may be required, which you can read about below.

  Things I like about this design:

  • Compact: It's small enough to fit onto a breadboard, and could even be used in projects in this form
  • Flexible: The antenna connectors give a lot of flexibility for what antennae can be used.
  • Simple: All the RF stuff is dealt with, you just need to slap on some antennae

  Things I don't like

  • Fiddly: The u.Fl antenna connectors and matching networks can be pretty hard to solder, meaning it might be challenging for some people to receive unsoldered/as a kit to assemble themselves. I could potentially replace the u.Fl connectors with/have option for SMA connectors but they're quite clunky and large.

  Lastly, I'm thinking about the real necessity of connectors for WiFi and GNSS. Potentially I could get away with on-board antennae for both of those since they're region agnostic, but the performance would undoubtedly be reduced.

  I'll mull it over, but any external input would be welcome!

• ​Finalised Design

  Sensors • 05/04/2020 at 11:19 • 0 comments

  I settled on the antenna connection locations and finished off the signal routing/via stitching yesterday. That allowed me to also finalise the  dimensions and put together a pretty 3D render!

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