Dendo SCM Shade

Dendo Systems has made motorized shades for two decades, sold through dealers to the pro market. The motors are solid. The problem was reaching consumers: the motors speak hardwired serial, not IP.

To get into Apple Home, Google Home, Alexa, and SmartThings all at once, Dendo needed a module that bridged their motors to Matter and plugged into any motor in the lineup, TU12 through RZ28 and beyond, without rewiring the motor.

We wrote the firmware for the SCM, a Smart Control Module that turns any Dendo motor into a Matter Window Covering (0x0202) over Thread + BLE. One module, any motor.

Two things had to be solved: power and the serial link.

The SCM talks to the motor over UART, and the whole system runs on a battery. A UART link that’s always listening drains it. We built the stack to keep the link awake only while a command is in flight and sleep it between transactions.

Thread was the bigger power draw. A radio that stays on to hold mesh topology will kill a battery device. We configured the SCM as a Synchronized Sleepy End Device and tuned the radio duty cycle down to the point where it still answers fast. The motor and the radio share a sleep schedule: wake on command, execute, sleep. Months of battery, near-instant response.

Because the SCM sits between the motor and the network, it sees every command no matter where it came from. When a wall switch moves the shade, the SCM detects it and pushes the new position into Matter, so the app never shows a stale position.

Certified July 2024 as Window Covering (0x0202). One module made any Dendo motor a Matter device in every major ecosystem.