Color silkscreen PN532 CH582 NFC card reader

In August, I received a free color screen printing voucher from JLCPCB. Seeing that most color screen printing projects on the JLCPCB open-source platform were microcontroller core boards or simple NFC cards, I designed this PN532 + CH582 card reader to make the most of this voucher (it needed both circuitry and a large area for color screen printing). Other PN532 projects on the JLCPCB open-source platform either directly expose the PN532's serial port or add a CH340, requiring dedicated host computer software. This project adds a CH582 to the PN532, allowing connection to a host computer via USB CDC serial port or BLE, or direct interaction between the CH582 microcontroller and the PN532. It also exposes a four-wire XH2.54 interface for serial displays, enabling the development of more applications.
The circuit design

uses the NXP PN532 chip, supporting multiple protocols such as ISO14443A/B, FeliCa, and NFCIP-1. It supports card reading, writing, and card emulation functions
, connecting to the main controller via UART, SPI, and I2C interfaces. This project uses a UART interface to connect to the CH582.
The PN532 chip on Taobao costs around 9 RMB, but there's a risk of counterfeit products (even from highly-rated shops) being unusable. It's recommended to buy a pre-built module for around 10 RMB and disassemble the chip.
The left side shows a usable PN532 chip removed from a PN532 module; the right side shows a 9 RMB chip from a certain shop, with obvious signs of polishing and solder oxidation, unusable on the board. Note the different shape of the bottom heatsink pad in the lower right corner. For debugging, test the 26-pin RSTOUT_N test point. After the chip completes reset, it should be 3.3V; if it remains at 0V, the chip or crystal oscillator is faulty.
The antenna matching circuit layout references NXP's AN10688, and the capacitor and resistor values ​​are based on yizhidianzi's engineering specifications. The measured sensing distance is approximately 4-5cm.
The PN532 crystal oscillator frequency is 27.12MHz, a less common model. Note that


the WCH CH582F low-power Bluetooth MCU chip has 32KB RAM and 512KB Flash, and two USB FS OTG controllers.
Only one USB port is actually used; it can be replaced with CH573F or CH571F, but the price is similar, around 2-3 yuan.
Firmware can be downloaded directly via USB without a programmer: Install WCHISPStudio, press and hold the SW1 button while inserting the USB into the computer, then select the firmware file in WCHISPStudio and click download.
The two-wire simulation interface is brought out to the SBU pin of the Type-C interface according to the project's scheme. Although there is currently no suitable debugger, the debug interface can be manually brought out using a Type-C test board. The
BLE antenna design is related to the board thickness. This project uses a 1.6mm board thickness.


The board is equipped with an MLT-5020 buzzer, which can be controlled by the TMR0 PWM output of CH582.
The color silkscreen image is from Unsplash and can be used for free commercial purposes. Front image, back image.
The color silkscreen is not heat resistant. I used a 260-degree reflow oven for soldering, and it turned a little yellow. It is recommended to use a lower temperature.


All components are surface mount. There are no protruding insertion holes on the bottom. The board can be placed flat on the table.

Firmware
. The firmware provided in this project is based on the WCH official example with simple modifications. It is relatively rudimentary. You can modify it as needed. The firmware functions are as follows:

When directly plugged into a computer's USB port, the red light illuminates, indicating that the CH582 will recognize it as a USB HID keyboard. When an ISO14443A card is detected, the blue light illuminates, a buzzer sounds, and it automatically reads the card's UID and simulates keyboard input of the UID, followed by pressing Enter, similar to the function of a barcode scanner.
Holding down the SW2 button while plugging into the computer's USB port will cause the CH582 to emulate the CH340 chip, recognizing it as a USB CDC serial port. It can be used with various PN532 serial port host computer software. Other PN532 projects on LCSC Open Source provide host computer software. The red and blue lights will flash alternately during data transmission and reception.
Press and hold the SW1 button while inserting the USB cable into the computer to enter ISP mode. You can download the firmware (the firmware is ch582-hid-cdc.hex, and the ch582-hid-cdc.zip file is the source code) via WCHISPStudio.

I tried using WCH's BLE serial port pass-through example, and it was possible to achieve BLE serial port pass-through through the WCH BLE Tool Android APP, but it didn't appear in the MTools BLE device list. This might be due to a different Feature ID; a compatible board is needed.
Refer to
other PN532 projects from LCSC , such as

the Hakurei Reimu project. The attachment contains the host computer software LiiGuang. More pictures
of the host computer software are also attached.