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Entrepreneur

[Interview AI] Stripe Payment Implementation: From test environment to monthly billing implementation using GCP and MongoDB

This article details the steps for implementing Stripe payments in Interview AI. First, obtain a Stripe test API key and set up a monthly plan. Next, prepare the back-end with GCP and MongoDB, and finally check the payment functionality in a test environment.
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.
Entrepreneur

[Mia] Want PR but not enough inventory? Reality of tightrope walking encountered in hardware

We have made a major update to Mia's functionality and we want to do a big PR campaign, but we have been plagued by a shortage problem and we have been keenly aware of the need for stock control and the psychological difficulty of PR, so we have described the stock problem. On reflection, ‘we should have moved on to the next order in a situation where we had plenty of stock’.
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

[MAX98357A] Changed IC package of class D amplifier from TQFN to WLP

The MAX98357A series of ClassD audio amplifiers is available in TQFN and WLP packages. The WLP package is smaller and more cost-effective than the conventional TQFN package, as it does not require expensive through-hole vias (connection pins that pass through the PCB).
application(Flutter)

[Flutter] How to convert m4a to mp3 using ffmpeg_kit_flutter_audio

Change to a policy of converting m4a to mp3 using the ffmpeg_kit_flutter_audio package. This package supports a wide range of formats using external libraries and includes the lame library needed for conversion to mp3 format.
Entrepreneur

[Mia] How to set up an interactive user experience on your website.

'Wouldn't it be possible to set up a 3D model of Mia on the HP and offer an interactive user experience on the HP as well, with a 360-degree rotation for viewing, and eyes that move and talk when you nod your head?' I came up with the idea.The part of Mia's head to be touched was made into an orange sphere (like a mandarin orange) to clearly indicate the part to be touched. The switching gif image and audio file were uploaded to the media and made a URL reference.
application(Flutter)

[Flutter] How to make a modal display scrollable in WebView.

There is a user settings screen in the application, in which the Terms of Use and Plapori items are prepared, so that when this item is tapped, each content is displayed in WebView and can also be closed. This time, since a simple implementation is sufficient, webview_flutter is introduced.