Datasheet CH9121 (Nanjing Qinheng Microelectronics) - 8

CH9121 Datasheet https://wch-ic.com
6. Function Descriptions 6.1 UART
CH9121 provides 2 UARTs: Port 1 and port 2. The UART signal lines include: serial data input pin RXD and serial data output pin TXD. CH9121T's serial port 1 also provides RTS and CTS for hardware automatic flow control at high baud rates. Through the serial interface, CH9121 can be connected point-to-point with MCU, DSP, or MCU with minimal wiring. The baud rate error of the CH9121 serial port transmitting signal is less than 0.3%, and the allowable baud rate error of the serial port receiving signal is not more than 2%. The serial data format supports 5, 6, 7, 8 data bits and 1 or 2 stop bits, and supports odd parity, even parity, no parity, blank 0 parity and mark 1 parity. The default is the standard byte transmission mode, including 1 start bit, 8 data bits, 1 stop bit, and no parity. Users can modify it according to actual needs.
6.1.1 Serial Baud Rate
The default serial communication baud rate of CH9121 is 9600bps. The user can select the appropriate communication baud rate at any time through the host computer software or serial port command code. After the configuration is completed, CH9121 saves the baud rate parameters to the internal storage space. After the chip is reset, CH9121 will work at the saved baud rate. CH9121 provides 2 serial port reference clock modes, the default mode is Default mode, users can select the appropriate serial port reference clock mode and baud rate according to the table below. Table 6-1 Serial port reference clock and serial port baud rate selection Serial port reference clock Baud rate (bps) Default mode Classical mode (Default mode) 300 Available Available 600 Available Available 1200 Available Available 2400 Available Available 4800 Available Available 9600 Available Available 14400 Available Available 19200 Available Available 38400 Available Available 57600 Available Available 115200 Available Available 230400 Available Unavailable 460800 Available Unavailable 921600 Available Unavailable 1M Unavailable Available 2M Unavailable Available 5M Unavailable Available 10M Unavailable Available Note: The 2 ports of CH9121 share a serial port reference clock. Users can set the two ports to different baud rates, but must ensure that both baud rates are available in the current serial port reference clock mode. V2.5 8 Document Outline 1. Overview 2. Features 3. Pinouts 4. Pin Definitions 5. Function Parameter Descriptions 5.1 Overview 5.2 Basic Parameters 5.3 Port Parameter 5.4 Default Configuration 6. Function Descriptions 6.1 UART 6.1.1 Serial Baud Rate 6.2 Other Hardware 7. Parameters 7.1 Absolute Maximum Value 7.2 Electrical Parameters 7.3 Power Consumption 7.4 AC Electrical Characteristics and Timing 8. Package Information 8.1 TSSOP20 8.2 LQFP64M 9. Applications 9.1 CH9121T Reference Circuit 9.2 CH9121A Reference Circuit