LPC Microcontrollers中的主题 LPC1766 UART send garbled

LPC1766 UART send garbled

125621365 — Sat, 16 Mar 2019 07:39:13 GMT

My code is below, when i run this code, I received the data like the picture. Anyone can tell me why?

Receive baudrate is 9600. Use TTL-USB connect to my computer.

int main(void) { uint32_t i,j, k=0; SystemInit(); UART0_Init(9600); UART0_SendString("hello world"); Delay(250); }

#define FOSC 12000000

#define FCCLK (FOSC * 8)

#define FCCO (FCCLK * 3)

#define FPCLK (FCCLK / 4)

void UART0_Init (uint32_t baudrate) { uint16_t usFdiv; /* UART0 */ LPC_PINCON->PINSEL0 |= (1 << 4); LPC_PINCON->PINSEL0 |= (1 << 6); LPC_UART0->LCR = 0x83; usFdiv = (FPCLK / 16) / baudrate; LPC_UART0->DLM = usFdiv / 256; LPC_UART0->DLL = usFdiv % 256; LPC_UART0->LCR = 0x03; LPC_UART0->FCR = 0x06; }

Re: LPC1766 UART send garbled

xiangjun_rong — Mon, 18 Mar 2019 03:36:16 GMT

Hi, Teng,

Regarding your question, I suppose that the incorrect baudrate leads to the issue.

From the code, it seems that the oscillator clock frequency is 12MHz, the cpu core clock frequency FCCLK is 12*8=96MHz, the uart0 driving clock frequency FPCLK is 96MHz/4=24MHz.

Pls confirm whether the peripheral clock is 24MHz, you can output FCCLK signal to CLKOUT pin and use scope to measure the frequency.

usFdiv = (FPCLK / 16) / baudrate; LPC_UART0->DLM = usFdiv / 256; //LPC_UART0->DLM = usFdiv>>8; LPC_UART0->DLL = usFdiv&0xFF;

BTW, I suppose you have to write the

PCLKSEL0&=~(0x03<<6); //select FCLK/4

Hope it can help you

BR

XiangJun Rong

Re: LPC1766 UART send garbled

125621365 — Mon, 18 Mar 2019 15:56:50 GMT

Thank you for your reply, I solved this problem. I used TTL to USB to receive the messages, but there is a MAX232 chip translate the signal to RS232. So when I used RS232 to USB then the data is normal.