Part of my project to write new firmware for the Aqara E1 Zigbee light switches involved implementing the Zigbee Cluster Library OTA Update function. It didn’t go particularly smoothly, with two main obstacles. Firstly:

Sanity check - Blinky For an initial sanity check, I modified the NXP SDK’s blinky example for the 4 LEDs of the Aqara QBKG41LM (DIO lines identified here) to make sure that it would accept and run new firmware.

Before progressing too far into the design/coding process, it’s useful to put down on “paper” a list of required and desired functionality, as well as a very preliminary idea of how the various pieces might be implemented.

Any new firmware needs to know the GPIOs After confirming that the chip had write access in ISP mode, the next step was to determine the appropriate inputs and outputs.

Aqara are one of the few manufacturers producing affordable, well built, Zigbee “compatible” light switches that are both available in my part of the world, and suitable for local electrical installations. Aqara are a brand of Xiaomi-backed Lumi United Tech.

The NXP Zigbee SDK is not well setup for use with C++. Although I prefer it over the Texas Instruments ZStack for various reasons, ease of C++ development is not one of them. I had no trouble converting ZStack sample programs to C++. I had all sorts of issues with the NXP SDK.

My attempt to develop custom firmware for the Aqara E1 Zigbee wall switch necessitated learning NXP’s Zigbee SDK for the JN5189.

Smart homes save energy right? Occupancy sensors turn off lights in vacant rooms, scenes and timers activate only the devices that are needed, only when they’re needed, and energy use feedback adjusts our behavior.

A comprehensive list of major Zigbee IC vendors and module makers, including a matrix of which module maker use which vendor's ICs.

After measuring the standby power consumption of various Zigbee and Z-Wave devices, I became curious about what efficiency regulations governed them. The EU has typically been at the forefront of energy use regulations, famously introducing the idea of a common charger back in 2009 before later mandating it, and issuing ecodesign requirements for transformers as early as 2009 (EC No 278/2009). Infact their first energy labelling directives were issued way back in in 1979.

NXPs MCUXpresso is not configured by default to build JN5189 SDK Zigbee apps on Linux, but with some minor tweaks, it is possible to build both the samples and your own applications.