Hello Yuanbin Zhou,
Sorry for my later reply.
Actually, the simple code you also can refer to the lpcopen code.
I have modify the lpcopen code like this:
#include "chip.h"
#include "board.h"
/*****************************************************************************
* Private types/enumerations/variables
****************************************************************************/
#define UARTNum 0
#define LPC_UART LPC_USART0
#define UARTx_IRQn USART0_IRQn
int main(void)
{
unsigned int i,j;
SystemCoreClockUpdate();
Board_Init();
Board_UART_Init(LPC_UART);
Chip_UART_Init(LPC_UART);
Chip_UART_SetBaud(LPC_UART, 115200);
Chip_UART_ConfigData(LPC_UART, UART_LCR_WLEN8 | UART_LCR_SBS_1BIT); /* Default 8-N-1 */
/* Enable UART Transmit */
Chip_UART_TXEnable(LPC_UART);
while(1)
{
for(i=0;i<100;i++) for(j=0;j<65535;j++);
while((Chip_UART_ReadLineStatus(LPC_USART0) & UART_LSR_THRE) != 0)
LPC_USART0->THR = (uint32_t)0X55;
}
}
It is just send 0X55 with 115200bps in UART0, PIO2_0 and PIO2-1.
I also attached my test project for your reference, and the following picture is the test result:

Wish it helps you!
Have a great day,
Kerry
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