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Nov/2022: New/simplified Build of HomeBrew ESP32 WiFi+Bluetooth adapter

This shows the new (Nov/2022) simpler design for the popular HomeBrew ESP32 based WiFi+BT adapter for Celestron telescopes. More detail will be added here over time, but there's enough info here now to build one.

Click here for the Arduino source code for the ESP32.

This is the latest wiring plan, showing all of the parts. Two diodes (1N4148, 1N5817, or even 1N4007), two 100K-ohm resistors, two 75K-ohm resistors, a tidy slider switch, a 30-pin ESP32 dev module, a DC-to-DC buck converter, and a 6P6C cable with an RJ12 plug on the end.If the buck converter is adjustable (rather than a fixed 5V output), then be sure to adjust it to give 5V output before assembling the project.Wire colours on the 6P6C cable don't mean anything, but their relative positions at the RJ12 plug are what counts.
The eight built-in resistors on the level-shifter board have to be removed (wrong values), as otherwise the AUX bus won't work afterwards. Just grab each one with needlenose pliers, and gently twist them off without pulling hard. Some of them may break: no big deal, just get all of the pieces off. Optionally, also remove the two outermost transistors, as we only use the two in the middle for this project.
There, the first one was easy! Only seven more to do..
The switch gets mounted first, to the underside of the ESP32, under the USB connector. Begin by scraping away the black stuff to reveal fresh copper in the pattern shown here. Don't scrape too deep, and stay well clear of the barely visible tracks adjacent to this area.
Check the fit of the switch, with one of the legs bent down/out as shown. That leg and each of the two sides of the switch should be contacting the bare copper patches.
Use flux, and smear some molten solder onto the scraped areas. Dragging the soldering iron back and forth on each area helps the solder to adhere and spread out.
Put the switch down on the solder, and press the top of it down with a tool as you re-melt the solder to stick it in place. Do the "leg" first, then each side of the body. Don't linger too long, or the plastic parts of the switch may melt!
Looking good.
While we're at it.. reinforce the USB connector. This is optional, but a Good Idea. Bend a short length of solid wire around the top front edge of the USB micro-B connector. Fold the wire back and under the board, with one leg on each side of the switch we just attached.
Solder the wire to the sides of the switch.
Also add a small amount of solder to the wire over the top front edge of the USB port. Done. Now the USB connector is far less likely to break off in use. Worth the effort.
We'll need some 3M double stick mounting tape now.
This is where the 3M tape goes. Trim it to fit, and avoid the antenna area at the bottom of this photo.
Stick down the buck converter and the level shifter in the areas pictured. Avoid the bottom part of the ESP32 board, so as not to interfere with its antenna. Wire up these parts as shown, including the two 100K resistors at LV2,LV3. The non-striped end of the diode on the IN+ line is not yet connected to anything. I also went and trimmed away all of the unused pins of the ESP32 module after wiring this, so that they don't stick out and make for an untidy product in the end.
Now wire up the two remaining 75K resistors as shown (the grey ones), connecting them to +5V. Do NOT solder them to the HV2/HV3 pads just yet -- there are other wires to also connect there first.
Here's the 6P6C (6 pole, 6 conductors) assembly that will be used. Conductor colours vary from cable to cable.
Here's the RJ12 plug, showing which wires are which colour inside this particular cable.For this particular cable, the colours work out as follows, from left to right:Not used -- WhiteRX -- Black (also not used)+12V -- RedTX -- GreenGND -- YellowBUSY -- Blue
Cable tie the 6P6C cable to a corner hole of the ESP32 board, to keep it in place while wiring (otherwise the wires will break). Connect the GND wire (yellow here) to OUT- on the buck converter, the +12V wire (red here) to the open end of the diode on IN+, the BUSY wire (blue here) to the HV2 pad and solder it there with the resistor. Also connect the TX wire (green here) to the HV3 pad and resistor, and solder those.Congratulations, it is now fully wired!
After programming the ESP32 and testing it, and then connecting to a mount and testing again, it can finally be encased in clear heat shrinkable tubing. I use 25.4mm (1") tubing from Amazon.
And there we have it: a nice, compact package.
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