LPC1754 UART3 Transmit Data when receive something

lpcware — Wed, 15 Jun 2016 18:04:53 GMT

Content originally posted in LPCWare by hofmannmb on Fri Dec 04 13:29:25 MST 2015
Hello!

I was using LPC1754 UART3 without problems, until I tried to use it with more than 1 byte at FIFO reception.

So, after I set up RX FIFO Trigger Level to 4 characters UART3 TX returns data over serial line every time when it receive some amount of data over RX line.

I eliminated all functions that send data over UART3 TX line, but it still answer each time that I send something on RX line. The most interesting thing is that U3TER register is set to 0 (zero), it means that transmissions should be blocked.

Below is my configuration code.

nvic_int_disable(NVIC_UART3);
nvic_clr_pend(NVIC_UART3);
PCONP_bit.PCUART3 = 1; /* turn uart on with cpu clock */
PCLKSEL1_bit.PCLK_UART3 = 1;
U3LCR |= (1u << 7);
U3DLM = fdiv / 256;
U3DLL = fdiv & (0xFF);
U3FDR = (divadd_val + (mul_val << 4));
U3LCR &= ~(1u << 7);
U3LCR |= (3u << 0); // 8 bits
U3FCR = 7; // Enable FIFO
U3TER = 0;
nvic_clr_pend(NVIC_UART3);
nvic_int_enable(NVIC_UART3);
U3IER_bit.RDAIE = 1; // Enable Rx interrupt
U3IER_bit.RXLSIE = 1; // Enable Line Status

Can someone help with this issue?

Any ideia about this?

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LPC1754 UART3 Transmit Data when receive something