Mini ESP32s3 Device Build
Well I have many ESPSomfy RTS devices and many different ESP32 versions. In testing different boards for compatibility, I bought some Xiao Mini ESP32s3 boards to try them out. Along, with the s3s I bought a few C3s and S2s all in the mini form factor. A few of these boards use external WiFi antennas and some use little ceramic antennas. In testing, all of them performed well. Those with the ceramic antennas had weaker WiFi reception but it was adequate if the WiFi network was good.
The Xiao S3 however comes with an external sticker antenna for the WiFi. Even in places where I expected to have spotty connectivity it performed exceedingly well and the WiFi is solid. This little bugger is tiny. For a size comparison see the pic below. The ESP32-WROOM module is on the left and the Xiao Mini ESP32s3 is on the right. The quarter is there for size comparison since that is about all the value it has these days.
Intrigued by the size of the little bugger, I decided that I would try my hand at miniaturization. The goal was to create the smallest ESPSomfy RTS device that I could without the benefit of a 3d printer or designing a PCB for it. After all I have a bunch of breakout boards laying around. The goal was to make something as tiny as I could. Just in case I decided to build a rocket to the moon I could take it with me while still having room for a couple of bottles of Scotch.
Digging around in my miscellaneous parts I came up with what I needed. Below is a pic of the items I used. I created a table below to give a better description of what these items are and where I got them. What isn't shown in the pic is the 28awg silicone wire that connected it all together. I used this wire because I have 10 different colors of it. As well, silicone wire is very bendy so it can be pushed into tight spaces although any small gauge wire would do.
The quarter is only there for size reference and the numbers were superimposed on the picture after it was taken. No need to get your hands on any of these items. The numbers are for reference to table below the pic.
| # | Part | Description | Sourcing |
|---|---|---|---|
| 1 | ABS Box | 58 x 35 x 15mm ABS box. | I bought a pack of 5 of these from Amazon |
| 2 | Breakout board | I had a Raspberry Pi breakout board laying around and figured why not. It has a section on it that nicely fit the ESP32 that I could solder the wires for the transceiver onto. More on this later. | You do not need this particular board but that is what was what I had laying around. |
| 3 | E07-M1101D Module | I have collected many of these little modules and had this sitting around in the parts. | You can find these all over the interweb. Search for E07-M1101D |
| 4 | ESP32s3 Mini | I used a Xiao ESP32s3 Mini for this build. It is tiny, powerful and has that cool little WiFi antenna sticker. This is the basic version. You do not need the Sense or the camera version. | Another Amazon item |
| 5 | Pin Header | The Xiao ESP32s3 does not come with pin headers. You will need a strip of 2.54mm single row header to solder the ESP32 to our breakout board. | I had these laying around but you can source them from lots of places |
This build required a few steps for assembly. Most notably as you can see the breakout board I used will not fit in the ABS box. You will need to cut it down to fit. I also carefully removed the pins from E07-M1101D so it too would fit into the tiny box.
I carefully cut the breakout board so that it would fit tightly into the dimensions of the ABS box. In the pic below you can see where I cut the board so that it fit into the box and the separation between the pins could be on each side of the ESP32. My goal for using and cutting this board like I did so I could easily solder the wires to the E07-M1101D onto the section between the pin headers. Once you have cut the breakout board make sure it fits inside the ABS box.
To cut the board I used my micro table saw. However you could use the cutoff wheel of a rotary tool, a hacksaw, bandsaw, or even score both sides with a utility knife and a straight edge. Then snap it apart.
The pins on the E07-M1101D had to be removed. These pins are too tall to fit within the ABS box. I suppose I could have used a larger box but that might take up space for Scotch on my moon journey. There is a trick to this as you do not want to damage the module as you pull out these pins. Take your time and do not try to force the pins out of the board.
Begin by heating your iron. Then heat each pin from the top of the board while applying light pressure to the pin to push it flush. If a pin doesn't want to push flush after about 5 seconds go on to the next one. Eventually they will start to work their way through the board. Take care not to damage the board with your iron.
Once the pins are flush you can now heat each pin and gently pull the remainder of the pin out using needlenose pliers. Don't force it if the pin is resisting, try another pin. The plastic part of the header is likely menacing you, eventually it will loosen against the pin. The more pins that get removed the easier it will become.
After getting the pins removed you can use some solder removal braid to clean up the excess solder. If you do not have any braid it also works to take a thin solid wire, heat the hole and push the wire through the hole where the pin used to be. I used a leg of wire from an LED that I had in the e-scrounge. We are doing this so that we can simply push the connector wire into the transceiver for soldering.
We are first going to mount the headers to the board we cut down. The location where I soldered the headers for mine is outlined in red below. I wanted the USB to be positioned as close to one edge of the box as possible but you can place these where you like. Just be sure that the spacing between them is the width of the ESP32s3.
We are going to be mounting the ESP32 to the side where the long pins are located. The short side of the header should be pushed into the board and soldered from the back side. In the end you want the plastic part of the header to create a space (raceway) for the wires to route between the ESP32s3 and the breakout board.
I used 28awg silicone wire to connect the transceiver to the breakout board. I found it easiest to solder the wire first to the transceiver then solder it to the breakout board. If you have the wire colors that I have you can use the color coding below but if you do not I would suggest making a chart of your own and record which color wire you soldered to which pin on the transceiver.
| Pin | Color | ESP32 | Description |
|---|---|---|---|
| 1 | Black | GND | Ground |
| 2 | Red | 3v3 | VCC |
| 3 | Green | GPIO3 | GDO0 - TX Pin |
| 4 | Blue | GPIO6 | CSN |
| 5 | Orange | GPIO7 | SCK |
| 6 | Purple | GPIO9 | MOSI |
| 7 | White | GPIO8 | MISO |
| 8 | Yellow | GPIO4 | GDO2 - RX Pin |
You want the wires coming out of the top of the board. If you examine the transceiver you will notice that the antenna is offset a bit so in order for it to lay flat in the bottom of the ABS box I routed the wire from top and soldered from the back. The top face of the board is the side with the screen printing.
I cut one 4inch length of wire of each color (8 pieces) then carefully matched them to the pin number below. Once I got all of the wires soldered to the transceiver I used a short piece of shrink tube to keep them together. I did this so that it was less likely to stress any one wire while soldering them to the board or handling during assembly.
Before mounting the ESP32s3 onto the breakout board I soldered the wires from the transceiver to the board between the sets of pins. This proved to provide a compact way of keeping the wires secure and relieve stress on the solder joints. When the ESP32s3 is finally soldered to the board, the wires will be between the two boards. The picture below highlights the locations where I soldered the wires.
Start with pin the pins that are closest to the transceiver while soldering and ensure at least 5/8 of an inch between each board. Cut the wire to length while keeping the proper distance between the boards. This way when you set it into the PVC enclosure it will fit neatly with the transceiver on one side and the ESP32s3 on the other. Optimum solder order 5, 4, 7, 6, 8, 2, 3, 1.
Before you solder the ESP32s3 to the pins first slide the ESP32 onto the top 1/3 of the pins of the headers ensuring the proper direction and pin alignment. The USB port should be protruding past the bottom edge of the board using the orientation pictured above. Do not push the ESP32 down all the way on the pins. Then, using slight pressure on only one side of the board, push one side down slightly more than the other. This will ensure good connection on the pins for testing.
Now install ESPSomfy RTS, if you have not already and configure the radio so that the pin functions match the layout. Test thoroughly as changing the wiring after you solder the ESP32 into place will become very difficult.
Once you are satisfied with the operation, push the ESP32s3 all the way down on the pins and solder it in place. Also take a small piece of electrical tape and cut a slit in it then place it over the exposed contacts on the antenna as pictured below. Do not skip this step, doing so will cause the ESP32 to reboot every time the exposed contact touches the metal shield or pins on the ESP32.
Position the assembly into the enclosure and mark where the USB connector and radio antenna will be exiting the case. NOTE: The radio antenna will exit low in the case as it is expect to sit nearly flush with the bottom of the case and you want the side of the case to stabilize the antenna module on one side. Study the pics and dry fit before cutting and drilling. Carefully use an x-acto or utility knife to cut the enclosure for the USB connector as shown and drill a hole for the antenna near the bottom of the enclosure. You will need to trim a little bit on the lid for the USB connector but that will hold it all in place.
With the and antenna in place I used some scrap ABS plastic and glued a couple of stops in place. I used ABS glue for black plastic pipes to glue it in place as it dries in about 5 minutes.
After you have fit the case to your liking, position the antenna on top of the board and close up the case. In the end I did not affix the antenna to the lid of the case since it makes it easier to remove the lid without damaging the antenna. I simply positioned it all carefully to ensure the antenna was not getting closed up by the lid and snapped it together. If the antenna is a little loose or the board moves around glue a couple of pieces of scrap ABS plastic to secure the board in place.
Once you are done you will have a device that looks like the one in the picture. And if you have a wishing well the quarter will have some utility. These days you can't even pay attention with a quarter. A few suggestions on this is that you should wish for at least $20 bill. While it won't buy you lunch, a trip to the moon, or even a bottle of Scotch, you can use it to buy parts to make another ESPSomfy RTS device.
