Use an "iTag" device and an ESP32 as a remote control button or switch.
The "iTag" is budget bluetooth locator tag similar to "Tile". When on, the iTag provides a bluetooth low energy server. An external device can connect and reqeust that the tag beep, as a means of locating a lost item. The tag will also beep when the connection is dropped as a means to remind you that you're leaving an item behind.
The iTag also has a button. When the button is pressed it will notify on a specific BLE Characteristic. This is often used as a shutter release or to activate a voice recorder on the host phone software.
These iTag style devices seem to be plentyful on Aliexpress. Most operate similarly, but of the few I have some are slightly different. You might need to edit UUIDs or experiment more with the source code to get any specific iTag device to connect.
The source code provided, once loaded on to the Mini32 will operate as follows:
- The device will search for known iTag devices. During this search the LED will blink.
- If it find ones, it will connect. The LED will go solid.
- Once connected, a press of the iTag button will blink the LED and also send a pulse to the defined MUTE_PIN, in my case GPIO17. On GPIO17, I have connected the optoisolator circut.
- Upon disconnect it will go back into scanning mode.
One unfortunate side effect is when the iTag is connected and TTGO module is powered down. The iTag takes this to mean the tag is "gone out of range" and it will beep. A button press will stop this, but I have found the iTag stops beeping eventually.
This was build from parts I had handly.
- A TTGO Mini32 or "TTGO T7" - provides a small ESP32 processor. The ESP32 has both WiFi and BLE but both can't really be used simultaneously due to memory constraints.
- A "Wemos DC Power Shield" - takes a 12v source and regulates it down to 5v. The TTGO Mini32 has another regulator to get down to the 3.3v operating voltage.
- A protoshiled with a PC817 opto isolator and resistor. You might need a second resisor if you intend to use this with a Valentine One. You could probably easily do this with a transistor, relay or some other switching method. (Note: I have not tested this extensively with either the R7 or the V1, so proceed at your own risk!)
I have released my portions of this project under GPL v3. It is based on some sample code which I belive is Licensed under Apache 2.0.
Basically, use the materials in this repository at your own risk.
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