Fanbee

FanBee :honeybee:

A Zigbee-controlled 140mm fan with electronically-controlled valve

Skip to the Build Guide if you want to know how to build one.

Introduction

User Interface

The small LED (D3) near the reset button indicates if the lowest (MCU) power rail has power. If it is not illuminated nothing will happen, check power rails.

The firmware initially starts blinking its status LED (D4, near the JTAG header) every 2 seconds, indicating that it is idle and is not connected to any network. Press the Pair button after your ZigBee network is ready to join a new device. The status LED will start to blink rapidly (every 0.5s) until it has joined a network, then it will turn off.

Pressing the pair button while the device is already joined to a network will result in two quick flashes of the status LED.

Long-pressing the pair button (>5s) will reset the device.

The last LED (D5) indicates if the fan is currently powered. It can be used to diagnose fan or connectivity issues.

Coordinator compatibility

Because the ZigBee HVAC fan device type is unfit for this device (it supports various modes but no speed control) I've opted to implement it as a generic level-controlled device (just like dimmable lights). This should give it fairly broad coordinator compatibility.

There's a device model for the FanBee in Zigbee2MQTT which is what I'm personally using to control them.

Notes

• The power connector is designed for daisy-chaining, that's why there are two positive and negative positions. Only one of each needs to be connected for normal operation.
• Second Servo output is not used currently, was used in an earlier revision and left for any future use as there was space.
• SPI flash can be left unpopulated if you don't ever want to use OTA updates or maybe a later (larger) firmware. It's currently unused.
• Newer TI SDKs have been tested but drop off the Zigbee network for unknown reasons after hours or days. Use the pinned version.
• Make sure that the surface your're installing the base plate on is flat. Otherwise the bell shape gets distorted and the butterfly valve disk gets stuck. The tolerances there need to be relatively tight to not allow too much air to go through in closed state.

Build Guide

Requirements

Off-the-shelf hardware

This was designed for the Noctua NF-A14 industrialPPC-24V-3000 SP IP67 PWM, but any other electrically-compatible 24V or 12V fans can be used. Note that the power supply voltage needs to match the fan voltage, there is no regulator for the fan power supply.

PCB

The control PCB is custom-designed and can be ordered at your favorite PCB manufacturer in various states of assembly. All SMT parts can be assembled for relatively cheap by JLCPCB. One PCB is needed for each FanBee.

A OpenOCD and JTAG compatible programmer with a 2.45mm ARM 10 Pin JTAG connector is required. This has been tested with a generic FT2232 board, but a TI XDS110 or compatible LaunchPad should also work.

Printed parts

The STLs for all printed parts are in the parts folder. One of each is needed for a single fanbee. servo_pulley.stl should be printed in resin or with a 0.2mm nozzle, the rest of the parts do not need to be as precise.

Assembly steps

1. Insert the 4 heat-set inserts into the studs for holding the PCB.
2. Insert the two heat-set inserts into the base for holding an optional PCB enclosure.
3. Insert a heat-set insert each into the bottom and top holes of the valve disk.
4. Press both ball bearings into their housings on the main part.
5. Place the fan at the back, route the wires through the slot and attach it with four fan screws.
6. Route the servo cables through the hole and attach the servo with two screws.
7. Attach the PCB with four 5mm screws.
8. Connect the 4-pin fan connector and 3-pin servo connector.
9. Place the fan disk between the bearings and push in the retaining pin from the bottom and the disk pulley from the top.
10. Secure the retaining pin with the 10mm M3 screw.
11. Secure the disk pulley with the 15mm M3 screw.
12. Push the servo pulley onto the servo and secure it with the provided screw.
13. Cut a sufficiently-long section of belt, loop it around the two servos and secure both ends with the belt retainer.
14. Attach the JTAG programmer and temporary power and flash the firmware.

Future work

• Public CI for firmware and manufacturing files
• Render/photos of the finished product

License

MIT for all the code I wrote as well as the CAD design files. Some code is also related to TI's SimpleLink SDK (especially the generated syscfg), I don't claim ownership of that, but TI grants you relatively broad permissions for most use.