Large Button Remote for Spraying

This project implements a STM32 based remote that simulates the encoding of ICs AUT980202 or AUT1080425 manufactured by ABOV. These ICs are found in plug-in wireless remote outlets sold under the brand name Woods, model 32555WD, also Fuji Spray model 3072, probably others.

I use this remote outlet to control the HVLP compressor in my shop. The original remote's buttons were getting clogged with finish. The benchtop housing I designed uses much larger buttons that won't be affected by finish buildup.

Any BluePill module source

ASK transmitter module 315MHz or 433MHz, depending on the frequency of the receiver. source

315MHz spring antenna source or 433MHz spring antenna source

(2) 8x8 non-latching button source Latching buttons can be converted to non-latching by removing a pin.

(1) 2x8cm prototype board.

3.7V 10440 600mAh Lithium ion rechargeable battery. Note that a regular AAA battery will not work. I can't find a source at a reasonable price. A few years ago I bought 20 for $1.25 each delivered from AliExpress. I think the postal services are cracking down on shipping lithium batteries.

(1) 5mm LED - red source

(1) 1/4 watt 10K ohm resistor.

1.5 & 2 mm heat shrink tubing

30 awg wire, assorted colors source

26 awg wire, black & red source

AA/AAA battery plates source

Screws: source & source

(1) M3 x 40 screw (or a 3mm nail cut to 45mm)

(2) M2 x 3 button head screw

(11) M2 x 4 button head screw

(1) M2 x 8 button head screw

(2) M2 washers.

(2) M2 x 5 flathead screw

(10) M2x3 brass inserts source

If you want to include a USB charger, include the following:

TC4056A micro USB battery charger module source. The micro USB version is easier to modify.

(1) 0603 3.9K resistor source

USB C power 2 pin jack source

USB C dust plug source

(1) 3mm LED - red source

(1) 3mm LED - blue source

I wasn't able to find documentation for either encoding IC. It was easy to see the format on a logic analyser tied to the data output of an ASK receiver. The AUT980202 format is shown below:

The smallest average pulse width was 215us, so a timer callback is called at this frequency. Then it's just a matter of producing a waveform that mimics the 315MHz original.

I recently purchased another remote outlet as a backup, but of course they updated the electronics to use a newer IC (AUT1080425), and changed the base frequency to 433MHz. The frame sent by the AUT1080425 is the same as the AUT980202 only there is no preamble.

For both ICs, the first 8 data bits is always 0110 1000, the next 4 bits is the command, either ON 0010, or off 0001, and the last 4 bits is the channel ID.

The channel ID is set at the factory by breaking the traces marked ABCD, where ABCD corresponds to 8421. The combination of the broken traces is the channel ID. The receiver and the remote come with a little channel ID sticker. In my case the letter "D" for the older 315MHz remote, and "I" for the 433MHz remote.

Example "D" is 0001. "I" is 1110. So to send ON for the "D" receiver, 0x6821 is sent. For the "I" receiver, 0x682E.

If you look at the receiver board, the tracings will be cut reflecting the channel ID label affixed to the receiver and remote. I was only able to determine channel IDs ABCD and I. For anything else you'll have to open up the recevier or remote, or go through all 16 combinations (0000 to 1111)

Board channel ID example where the "D" trace is cut:

Board channel ID example where the three traces are cut to represent "I":

As noted in the introduction, this is a STM32 simulation of the original remote encoding ICs. You can download the sources for this Arduino project here. There are two possible changes you need to make in the Config.h file. You have to determine your channel ID as shown in the previous step and modify kChannelID. You also need to determine your encoding IC and set the appropriate #define at the top of the file, either AUT980202 for 315MHz or AUT1080425D for 433MHz.

If your Arduino IDE doesn't have the STM32 package you can load it via the Arduino Tools menu. I'm not going to go into any detail about how to load a sketch onto a BluePill module using a STLink programmer. You can easily find many instructional sources for this.

These are the settings I used:

Load the sketch onto the BluePill module after the next step.

3D print the STL files attached below. I used PLA. You'll need two Buttons. I printed one red, one green. The buttons are printed on their side, with support. The tiny Plug and Strap STLs should be printed solid. The Base is printed with support. The Top needs to be rotated so that it's sitting flat with the side wall facing up.

The support for the base print is kind of a pain to remove. I use bent nose pliers and a flat blade screwdriver to remove the supports. The hole for the button hinge pin screw (M3x40) needs to be drilled out to 3mm. Only drill out the first 2 barriers, leaving the end untouched so that the screw threads have something to cling to.

Add/hot melt 8 M2x3 brass inserts to the top, and 2 to the base.

Mount the 2cm wide proto board in a vise and score it on both sides using a utility knife. Snap the board off at the score lines to get 2 boards as shown below:

See the attached AUT980202_Remote Sch schematic.

The 8x8 switches are 2 pole, 2 throw. One pole on each switch controls the +5V power line to the BluePill, the other pole on each switch controls the ON and OFF lines from the BluePill. The BluePill is only on for as long as one of the buttons is held down. I'm not going to provide exact measurements for each wire. I just kind of eyeballed it as I went along. The BluePill module sits on the the bottom of the base.

The BluePill needs to be modified as shown below:

Note that the schematic doesn't show the inline 10K resistor. Don't forget to add it or you will damage the mcu.

The transmitter slides into the slots on the back. The transmitter generally comes with an angled header. The angled header needs to be removed. If you decide not to solder the wires directly, the header you use must be straight, otherwise it will touch the BluePill board. Solder on the spring antenna so that it's parallel with the top of the module.

There isn't a huge amount of space. You want to run the wires so they stay away from the arms on the 3D printed button STLs. For the wires to the 8x8 switches and the 5mm LED that attach to the top, the wires are run so they stay in the center of the base (see photo.) In the photo there's a common 30awg ground wire (black), and 30awg red and green wires. The heavier 26awg red +5V power wires are common to both switches. Note that the proto boards may need to be filed to fit around the 5mm LED mounting hole.

Solder the battery spring plates as shown. It's hard to see in the photo, but the tab on the spring plate is folded back and the wire is attached so that when the wire is inserted into the hole in the battery compartment, the 2 barbs on each plate are pointing up, away from the wire. You may need to clean out the 2mm holes for each wire.

Optional: If you're going to include a battery charger, it slides into slots on the side with the battery connection down. Wire the charging status LEDs as shown. Because the project uses a 10440 battery, the 1.2K ohm resistor R3 needs to be replaced with a 3.9K. This will change the charging profile to extend the life of the smaller battery. These charging modules come with R3 sized for the larger 18650 battery.

The 3mm charger status LEDs are inserted in the back of the base and held in place by a M2x4 screw. The head of the screw can be accessed through the front of the base using a long 1.3mm hex key.

Insert the USB C 2 pin power jack into the hole below the status LEDs. Attach the wires to the charger board as noted in the schematic.

Use the schematic to complete the wiring. Insert the battery, charging as needed, and verify the operation of the remote with the remote switch.

Once complete, insert the BluePill module so that it sits on the the bottom of the base held in by 2 M2x3 screws and 2 M2x4 screws+washers. There are 4 holes in the bottom of the base for these screws. Slide in the transmitter and the optional battery charger.

Insert the 2 buttons into the slots on the front of the base. Slide in the M3x40 hinge pin and tighten once the last of 3 supports are hit. Once the buttons are moving freely, you can insert the plug to cover the hinge pin hole.

Attach the 5mm LED to the top. You may have to drill out the hole to 5mm. Secure the 5mm LED using the 3D printed strap and a M2x8 screw.

Attach the switch PCB assemblies using 8 M2x4 screws.

Fold the wires into the enclosure, making sure they will not interfere with the 3D printed buttons.

Make sure nothing is touching the spring antenna.

Attach the top using 2 M2x5 flathead screws. Note you may need to use a countersink bit to dress the holes so that the screws are flush with the top.

That's it. I hope you found this project interesting. Send me a message if you have any questions.