Interrupt driven UART

This is non HAL code in NIOS1 but it is currently working fine in NIOS2 as well

include

# include "excalibur.h"

global

//Make sure you have a uart in excalibur.h that matches your uart name (na_uartxxxx)

np_uart *uart1 = (np_uart *)na_uart_1;

init the uart

void uart1_setup(void)

{

//UART 1 setup -----------------------

uart1->np_uartstatus = 0; // clear the interrupt condition

nr_installuserisr(na_uart_1_irq ,UART1_ISR,(int)uart1);

uart1->np_uartcontrol=0;

uart1->np_uartcontrol = uart1->np_uartcontrol | (np_uartcontrol_irrdy_mask);

}

irq routine

void UART1_ISR(int context)

{

np_uart *uart1 = (np_uart *)context;

int status;

unsigned char rxChar;

status = uart1->np_uartstatus;

rxChar = (unsigned char)uart1->np_uartrxdata;

uart1->np_uartstatus = 0; // clear the interrupt condition

if(status & np_uartstatus_rrdy_mask) // character arrived?

{

// Write code to handle rxchar;

}

if(status & np_uartstatus_trdy_mask) // character arrived?

{

if (more bytes to transmit?)

{

// Write code to send next byte

uart1->np_uarttxdata=next byte

}

else

{

// Set the port to read only

uart1->np_uartcontrol = np_uartcontrol_irrdy_mask; //only Rx enable (if half duplex)

}

}

}

to start a transmit sequence start by sending a byte and then enabling the Tx IRQ flag.

uart1->np_uarttxdata=tx1_buffer[0]; // send first byte. IRQ will do the rest

uart1->np_uartcontrol =np_uartcontrol_itrdy_mask; // only Tx enable

you can have rx irq flag enabled all the time for full duplex. Just write your code to handle it.

First use a fix baud rate (as defined in SOPC builder) before playing with your own software settings. Fix baud rates uses less LEs.

to test connect the 2 pins (Tx,Rx) either in software or hardware and send a few bytes and return the status with a printf or 2.

To make life easier implement a ring buffer for the received character and parse it outside the irq. Don't put too much inside the IRQ routine. Just grab and store.

Victor

http://www.zerksus.com (http://www.zerksus.com)