The area between a transceiver's output contacts and the resonating antenna is usually specified to be fifty ohm impedence. The variety of active and passive parts (inductors, capacitors, switches) tune the circuits to a target frequency. Sendcomm targets users of approximately 900 MHz ISM bands, and testing the radio path on three frequencies (868, 915, 923) results in good radio accuracy.

For those recommending commercialisation, industrialisation, or sales efforts with radio devices, we suggest learning about EMC testing, licensing, and certification.

Near field testing

At a minimum there must be near field testing using test receivers and spectrum analysers (of typical cost 100K.) Far field test tooling is more complicated, with unknown (could be tenfold) costs.

Anechoic chambers

Don't forget that at least one test facility offering anechoic chamber access must be contracted, and the procedure is quite involved. Accuracy of the one hundred million euro anechoic facilities is not needed, but it's unclear if the smallest chambers can support subgigaherz testing.

Common directives

Some directives implying product compliance include ECCN, HTSUS, and:

RoHS and WEEE

Device and accessories

• Accordance to the RoHS Directive (2002/95/EC)
• Accordance to the WEEE Directive (2002/96/EC)

CE and FCC

Provision

• FCC part 15 subpart B
• 2002/95/EC (RoHS, WEEE)
• Directive 2004/108/EC (class B)

Evaluation

• EN 61000-6-1 (2007)
• EN 61000-6-3 (2007) + A1(2011)
• FCC CFR 47 Part 15 (2013)

Compatibility

• EN 55022
• EN 55024

Application engineering provides a starting point for education groups to develop their curriculum. Interim results of application engineering illustrate a LoRaWAN exchange.

The current state of firmware development reads from the controller's internal temperature sensor.

Once the etching services concludes and boards arrive, we populate the 124 part devices using an in house surface mounted technology (SMT) assembly line.

The resulting boards are zeta grade prototypes, viable devices which determine distribution strategy after electronic design automation (EDA) electrical, alpha, and beta program tests.

These devices are transmitting at fifty metre gateway distance with a five to nine dB signal to noise ratio (SNR), qualifying our design as high performance (Typical LoRa SNR values are between -20dB and +10dB) according to online documents.

Today we introduce a new LoRa research design accommodating on-die (SoC) ST parts, not yet available to the public. To further support research and higher education tasks, we include interfaces to PMOD, Click, and Grove peripherals.

In a related development, an interface to a (future design) integrated FOMU circuit is earmarked for developmental consideration.

A Sendcomm working layout (pending assembly and test) is complete. We're surprised to see the parts count surpass 100, and the current count stands at 124.

As our transceiver selection improved and became microcontroller integrated, we no longer require external processing. Therefore, connected hosts (when our devices do not operate stand alone) are less useful.

Update 1

To bridge the gap presented by controller useless connected hosts, we add the requirement of monolithic kernel friendly operating environment and IP network stack integration.

This disqualifies the Arduino, Micro:bit, and NodeMCU hosts, which we replace with Khadas Vim and Up Board computers.

Update 2

Due to Khadas unavailability, we are back to the mostly original lineup:

• Raspberry Pi
• Beaglebone Black
• Arduino Uno
• NXP FRDM
• UP2 Board
• Micro:bit

Hardware and firmware quality assurance begins, with attention placed on test driven development. We obtained a empty test harness to customise, as well as expanding our local fabrication laboratory with metal workshop machines to create manual test jigs. Schematic capture and layout design efforts are developing around the concept of distributing a general use transceiver device and several daughterboards.

Components to be tested include Keystone standoffs for mounting to the jig and Mill-Max pogopins for connection to the test controller. A test plan includes unit tests documented in the firmware.

The first generation of LoRaWAN 1.1 capable IC (Integrated Circuit) and MCU (Microcontroller Unit) parts is appearing in Q4 2020, so we are finally able to implement the advanced research features most relevant to higher education.

Design of circuits based on these new chips is in progress and revision controlled in source code management. The relevant milestones include:

To serve as a backup choice, symbols and footprints of the Microchip ATSAMR34 were created. After discussions with vendors we chose the STM32WLE5 UHF low power microcontroller, and have a design using it. A number of STM32WLE5CCU parts are in transit and will be used on boards in fabrication.

To offer researchers a flexible platform of connected sensors as well as support its use in existing devices, the standalone radio device boots and executes commands from a connected USB client. The standalone device connects with a optional daughterboard which may include sensors, actuators, and headers for a number of serially connected hosts (Beagleboard, Raspberry Pi, Arduino, FRDM-K64F, and Microbit.)

Hosting Developments

To support better work distribution and benefit from modern features, we've completed a round of improvements throughout our hosting platforms.

Digitalocean Migration

Using the DigitalOcean infrastructure as a service provider allows us to focus on hardware and software engineering while implementing the most urgent network services quickly and easily.

This means we're no longer using Red Hat OpenShift for computing, although our dedicated selfhosted systems in a nearby datacenter are in service for the long term.

Europalab

The Europalab Networks source code management system

Europalab NetworksEuropalab

Europalab Software - Home

Europalab software provides logic to a diverse base of consumers. This collection leverages the work, knowlege, and experience gained through years of engineering. Development is undertaken according to sound software engineering principles.

Michael Schloh von BennewitzSoftware Europalab software collection

We're happy to report that a new mechanical stretched stencil frame is in use.

We decided against pneumatic powered machines after learning that the tension strength of mechanical frames is of equal value (about thirty to thirty five newtons force) while requiring no compressor attachment.

A single stencil foil is usually designed for several board layers and sometimes a foil is hacked to fit different designs, with selective population as shown.

After speaking to Microchip representatives as well at colleagues at The Things Industries, we've decided to replace current module based LoRa hardware and software stacks with the ATSAMR34J18 which includes a MCU with USB.

It will be a welcome challenge to integrate tooling for the 64-pin 6mm square BGA with dense 0,65mm pitch between balls.

ATSAMR34J18 - Wireless IC

LoRa Sub-GHz SiP

Microchip logo

Updated Tools

We have been loaned a SAMR34 Xplained Pro Evaluation Kit by Microchip Technology. Our particular model includes a Atmel WLR089 module, which bundles the ATSAMR34 MCU with a subgigaherz Semtech SX1276 transceiver and several other components. We received this developer kit that is not available on the market yet.

Combining schematic capture, power circuit simulation, firmware development, and user interface design is leading to a Europalab Devices reference implementation for servomotor control systems.

Today we completed a dedicated support site, allowing the users of Europalab devices and services to seek answers more easily.

The Europalab support and help desk is now a publicly accessible web application, check it out.

We hope you use and like it.