Nowadays, smartphones are equipped with recording functions, leading to a decline in the popularity of traditional recording pens. As a result, professional recording pens are delving deeper into meeting user demands, such as extending recording time, preventing static interference, and enhancing recording quality.

The most common type in the market is the digital recording pen, also known as a digital recording stick or digital voice recorder. It is a type of digital recorder designed for easy operation and improved recording quality, not necessarily in the form of a traditional pen. It is portable and comes with various functionalities, such as laser pen, FM radio, MP3 player, etc. Unlike traditional tape-based recording devices, digital recording pens record audio using digital storage.

In the past, there were many manufacturers producing chips for recording pens, both foreign and domestic. However, there are fewer options available now. Some commonly used chips for recording pens include AP902, AP903, AP912, AP916, AP909, AP919, AP929, AP702, AP711, and AP732. SRS chips include AP8111, AP8202, AP8302, AP8206, and AP8306.

Let's take AP732 as an example for analysis. AP732 is a professional digital voice recorder (DVR) control chip that offers long recording time, high sound quality, and post-editing capabilities. It is used for digital recording and playback of voice signals. AP732 features an embedded 16-bit digital signal processor for voice signal encoding and decoding and an 8-bit microcontroller for managing user interface and memory functions. The chip includes a NAND flash interface, enabling the storage of recorded voice signals in multi-level cell (MLC) NAND flash memory. The built-in USB interface facilitates transferring the recording information from the digital voice recorder to a personal computer for storage and backup. AP732 also incorporates automatic level control input, which significantly reduces the demand for external components when designing microphone-related products.

As there are numerous recording pen solutions available, it is possible to design one's own recording pen. The working principle of a digital recording pen involves sampling and encoding analog signals into digital signals using analog-to-digital converters. These digital signals are then stored after compression. Even after multiple copies, the audio information remains intact without any loss, preserving the original sound quality.