LPC1837 receiving data on UART

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by jb111 on Thu Jan 29 18:07:04 MST 2015

Im using the LPC1837 with LPCExpresso. So far Ive been able to send characters via UART0, but I am unable to receive any characters. Ive been using the uart functions from the header lpc18xx_uart.h in the CMSIS driver library.

I think I have narrowed it down to a  problem in software, as I've scoped the receive line when I send data. I also set the RX pin as a GPIO and was able to scope the pin toggling. I don't think its a baud rate issue since i can send data and read it on the other side.

Even when I send data the Line Status Register(LSR) doesn't show any change on the RDR bit (ie that its empty).

I've scoured the user manual and cant find anything... I think Im not setting a register correctly but don't know which one. My USART0 registers are all zero except for:
IIR = 0x01
LCR= 0x3

My code is as follows:

// Set Pin mode to RX
LPC_SCU->SFSP2_1 = (0x07 & 0x01);

//Condfigure Uart0 with fucntions from lpc18xx_uart.h
UART_CFG_Type  uartCfg;

while(1) {

lsr= UART_GetLineStatus(LPC_USART0);
a= UART_ReceiveByte(LPC_USART0);

//check if has received anything on LSR RBR bit
b=lsr & 1;
//send data back

Any help would be greatly appreciated.