The long-range LoRa® wall switch powered by coin cells and the Arduino IDE

Sep 04, 2019

Project update 8 of 9

Busy August: PCB Delivery, Components Arrived, Some Delays

We have received the components from Mouser, and all of the finished PCBs. Now that we have received these items, we can assess our status.

We had a busy August. Below is an update on what we’ve been doing this past month:

Swag Bonus Items and a Live RFM 69 CW Test

First, some good news! The final calculations give us some space to add an Arduino-Nano clone and FTDI programming header with pogo connectors to all backer orders.

In addition, we’re running a new battery survival live test with RFM 69 CW for all who bought those EasySwitchBoxes with these amazing radios. Follow along with us and watch how many transmissions it will survive!

Check out the live results, available here: https://io.adafruit.com/easySensors/feeds/rfm69cw-battery-survival-test

The last test of LoRa radio was success. We estimated about 6,000 - 7,000 transmissions but it managed to send 10,034 messages with voltage levels, plus it was all acknowledged messages with confirmations, while on some generic coin cells.

Component Costs

Our participation in the Microchip Get Launched 2019 design competition gave us reduced-price parts for the initial production run - which turned out to be a big help! Without this discounted pricing, our small order would have been much more expensive. Unfortunately it took almost 3 weeks to negotiate; a big company and small order turned out to be a complicated matter. Thanks Crowd Supply for the great support!

PCBWay Antenna Boards: Bad Run

The boards initially failed fly probe tests and so PCBway rearranged all antenna boards production. It happens and it is part of the production process. Thanks PCBway for checking! Check out this fly probe video we made while we had a chance to visit PCBway factory this February:

The probes do all connection tests of the PCB. If something is not right with electrical connectivity, the board is marked as failed.

Logistics Assumption Was a Bit Wrong

We did not double-check with Mouser and thought that since they have a Chinese version of their site, they must have a warehouse there. Wrong; all shipping (even worldwide) comes from Houston, Texas. Instead of what would have been one leg China local delivery, in fact it turned into extra 2 legs: from Texas to Portland, from Portland to China.

Functional Tests and PCBA

Our assembly costs also increased since we lowered our order quantity, and we decided to do the PCBA and functional tests locally in Belarus since we have negotiated much better deal than in China. Overall, we estimate this will cause a four week delay. This is unfortunate, but if we had stuck to our plan with China, the delay would have been even longer and more expensive (with additional shipping times, costs, etc.).

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