It may be extraordinarily irritating when electronics virtually do what you need, however not fairly. In these instances, you’ll be able to both settle for the system as is, or you’ll be able to seize your soldering iron and do one thing about it. YouTuber Mellow_Labs lately discovered himself on this state of affairs and made the choice to do one thing about it.
Mellow_Labs picked up an inexpensive Bluetooth multimeter that streams its readings wirelessly to a cellphone app in order that he might simply present viewers what he was seeing in his venture movies. However utilizing a cellphone app wasn’t ultimate — he wished these measurements to be accessible from wherever. Nearly each system has an online browser nowadays, so an online server would do the trick, however the inventory multimeter could not deal with that.
Mellow_Labs cracked the case open to see what might be finished about this drawback. He discovered a thriller chip coated in an epoxy blob and a Bluetooth module. After monitoring down the datasheet for the module, and likewise a particularly useful GitHub repository that detailed the {hardware} and software program of the multimeter, he was prepared to begin fixing issues.
The plan was to interchange the Bluetooth module with an ESP32 chip. That may permit the multimeter to host an online server that serves up an online web page exhibiting the system’s measurements in actual time. However first, the communication protocol would must be cracked. After hooking the Rx and Tx strains from the Bluetooth module as much as a logic analyzer with a UART decoder, Mellow_Labs discovered that the protocol was fairly easy. Small knowledge packets had been XOR encoded by a continuing worth. With that data, the information strains might be wired to the ESP32, which might decode the information and serve it up in an online web page.
The very last thing to do was to energy the brand new parts. A voltage enhance converter elevated the voltage stage from the multimeter’s batteries in order that they might energy the ESP32, and a MOSFET was related to the Bluetooth allow sign in order that it will solely be powered up when readings had been being streamed. And with that, this system lastly did precisely what Mellow_Labs wished it to do.
This multimeter reveals its measurements on an online web page (📷: Mellow_Labs)
Testing the ESP32 board (📷: Mellow_Labs)
