Software program developer Alistair Francis has added a little bit of exterior intelligence to the very-disconnected Husqvarna Automower 305, by reverse engineering its Bluetooth Low Power (BLE) interface — to attach it to House Assistant for built-in management.
“I just lately bought a Husqvarna Automower 305. It’s a robotic mower that may drive across the yard slicing the grass,” Francis explains. “Though some Automowers assist a cloud connection, I particularly purchased one that did not embrace web entry.
“The 305 has no web, Wi-Fi or cloud connection. This implies the producer cannot implement a subscription service, the system is not uncovered to web large cyber assaults, and it ended up being the most cost effective possibility. The down aspect is that I can’t talk with the system from my House Assistant occasion.”
What do you do if you wish to automate the very-disconnected Husqvarna Automower 305? Reverse engineer it, after all. (📷: Husqvarna)
Whereas the Husqvarna Automower 305 lacks devoted wide-area community connectivity, it isn’t completely with out radios: the robo-mower consists of Bluetooth Low Power connectivity, designed to be used with a companion smartphone app. “I believed I may reverse engineer the protocol,” Francis says, “and assist it in House Assistant. That approach I can use a ESPHome Bluetooth Proxy to regulate the mower through House Assistant.”
Utilizing a Nordic nRF52840 dongle and a duplicate of Wireshark, Francis was capable of sniff the packets despatched between the mower and the app — however the visitors was encrypted. “Fortunately legacy Bluetooth isn’t very safe,” Francis notes. “I reset the pairings on the mower and telephone and this time paired the 2 whereas Wireshark was working. Older Bluetooth protocols ship the encryption key in plain textual content throughout pairing. So Wireshark may learn the important thing after which routinely decrypt the visitors.”
Between captured-and-decrypted packets and a decompiled Android app, the Automower gave up its secrets and techniques. (📷: Alistair Francis)
Sadly, the protocol seemed to be extra advanced than hoped — so Francis turned to decompiling the Android app, discovering the Java code chargeable for producing packets and sending them over Bluetooth Low Power. With the protocol thusly decoded, Francis was capable of write Python scripts for management of the mower — and for integration into House Assistant, together with the remainder of his residence automation {hardware}.
The complete write-up is offered on Francis’ weblog, with the ensuing Python scripts revealed to GitHub beneath the reciprocal GNU Basic Public License 3.
