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ESP32

Development/Design

[ESP32 custom board] Result of investigating the cause of board defects by measuring voltage with an oscilloscope.

When wiring voltage is to be measured, the wiring on the board is often covered with resist (insulation layer), so voltage cannot be measured by applying a probe over the wiring as it is, so lightly scratch the area to be measured with a cutter to expose the copper foil part before measuring the voltage.
built-in(C++)

[ESP32] Modified circuit with power supply noise countermeasures to avoid surface mounting errors.

The MAX98357 itself needs to be connected to pins 25, 26 and 22 of the ESP32 WROOM 32E. keep the I2S signals (BCLK, LRCLK and DIN) as close as possible to pins 25 and 26 of the ESP32, as keeping the wires short reduces the risk of signal degradation and cross-talk. Attempt to optimise decoupling capacitors in the circuitry around the power supply to reduce power supply noise.
built-in(C++)

[ESP32] Investigation of the cause of cracked speaker sound and no playback due to wiring error (magnifying glass and oscilloscope)

When the IC package of the Class D amplifier was changed from TQFN to WLP, 4 out of 25 were defective in the speaker area as follows. Investigate the cause of sound crackling and audio not being played back. Verify if the sound crackling is resolved by first lowering the volume in the application. Next, using a magnifying glass, visually check for wiring defects.
Development/Design

[Stock issue] What if a part is out of stock when I place my order? Using JLCPCB’s pre-order.

In order to deal with out-of-stock issues like this one when they decide to order, JLCPCB allows pre-ordering, which means that the parts can be ordered before the PCB assembly is ordered and kept in stock at JLCPCB until the PCBA service is required. These pre-ordered parts are sent together with the PCB (and surface mount if you have also asked for surface mount), rather than separately from the PCB and only the parts are sent to you.
Development/Design

[ESP32] Understanding the automatic boot loader mechanism and truth table

The automatic bootloader of the ESP32 is a function that enables automatic programme writing when the PC instructs the programmer to write the programme (by pressing the Upload button on PlatformIO) without having to manually press the EN or BOOT (IO0) pins.
application(Flutter)

[Flutter × Go × ESP32] How to add mute function to Mia.

After the release of the beta version of Mia, several users who actually used it asked for a 'no talking mode' for the frequency of talking, so the implementation of this feature is described in this report. For reference, we looked at Alexa and found that mute (in this case, goodnight mode) was indeed displayed on the home screen with a toggle icon.
application(Flutter)

[ESP32] Implementation of Deep Sleep Mode and Timer Wake-Up Function

Introduction. Developing "Mia," a talking cat-shaped robot that speaks dialects. After releasing the beta version, sever...
application(Flutter)

[ESP32 x Flutter] How to send Wi-Fi scan results in chunks via BLE

Describes how to use ESP32 and Flutter (flutter_blue_plus) to split and send the results of a Wi-Fi scan to a smartphone via BLE, using BLE's Notify function to split large data into smaller packets and reconstruct the received data.
Development/Design

Create PCB by EasyEDA and order PCB by JLCPCB. If you want to keep costs down, request 2 boards to be mounted.

Create schematics in EasyEDA and convert the schematics to PCBs Work on the PCBs includes component placement, number printing, board outline drawing, wiring with auto routing, creating mounting holes and creating solid copper foil After completing the work on the PCBs, order the boards from JLCPCB.
Development/Design

[ESP32] Electronic circuit of the self-made board that can also be driven by LiPo battery

Describes the process of creating a home-made ESP32 board that can support both USB Type-C and LiPo batteries. The charging current is regulated by PROG and the voltage regulator is switched from AMS1117 to ME6211 series; an automatic switching circuit is implemented using PMOSFETs.