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UART Usage Tutorial

Contents

UART Usage Tutorial#

What is UART?#

UART (Universal Asynchronous Receiver/Transmitter) is a common serial communication protocol used to send and receive data between devices in a serial manner. It is widely used for:

Serial terminal debugging
Communication with sensors or external modules (e.g., GPS, GSM modules)
Data exchange between master and slave devices

K230 UART Features#

Feature	Description
Number of supported channels	5 UARTs: UART0 ~ UART4
Available channel description	UART0 is occupied by system debugging, UART1, 2, 3, 4 are available
Configurable parameters	Baud rate, data bits, stop bits, parity bits, etc.
Pin multiplexing	Supports setting any IO to UART function via IOMUX
Data operation methods	Supports methods such as `write()`, `read()`, `readline()`, `readinto()`

Application Example: Serial Send/Receive Test#

The following example demonstrates how to initialize the UART1 interface and perform data sending and receiving operations.

Example Code#

from machine import UART

# ========== 初始化 UART1 ==========
u1 = UART(
    UART.UART1,           # UART1 通道
    baudrate=115200,      # 波特率 115200
    bits=UART.EIGHTBITS,  # 数据位 8 位
    parity=UART.PARITY_NONE,  # 无校验
    stop=UART.STOPBITS_ONE    # 停止位 1 位
)

# ========== 发送数据 ==========
u1.write("UART1 test")  # 发送字符串

# ========== 读取数据 ==========
r = u1.read()            # 读取接收到的字节数据（可能为 None）
r = u1.readline()        # 读取一整行数据（以换行符结尾）
b = bytearray(8)
u1.readinto(b)           # 将接收到的数据填充到 bytearray 中

# ========== 释放资源 ==========
u1.deinit()

Interface Description#

Method Name	Description
`UART()`	Create a UART object, specifying the channel number and communication parameters
`write(data)`	Write a string or byte data to the serial port
`read()`	Read all available data, return a bytes object or None
`readline()`	Read one line of data, terminated by a newline character `\n`
`readinto(buf)`	Read data into the specified buffer (such as `bytearray`)
`deinit()`	Stop the serial port and release resources

Application Scenario Examples#

Serial debug output: replace print(), making it easier for external devices to monitor logs
Communicate with serial modules: such as Bluetooth, LoRa, 4G modules
Multi-serial concurrent task processing: connect multiple peripherals through UART1/2/4

Troubleshooting#

Issue	Troubleshooting Suggestions
Unable to receive data	Check the baud rate settings and whether the IO mapping is correct
Received data is garbled	Confirm that the communication parameters on both ends are consistent (baud rate, data bits, etc.)
Read result is None	There is no readable data in the serial port buffer
UART0/UART3 cannot be used	These two channels are occupied by the system; it is recommended to use UART1/2/4

Further Reading#