NiosII UART HAL

the niosII uart hal does not support hardware handshake.

Main problem is that it does not resets RTS if the circular receive buffer gets

full.

I modified altera_avalon_uart.c in the following way (perhaps not the best

way but it seems to work):

.. in altera_avalon_uart.h

/*

* ALT_AVALON_UART_BUF_LEN is the length of the circular buffers used to hold

* pending transmit and receive data. This value must be a power of two.

*/

# define ALT_AVALON_UART_BUF_LEN (64)# define ALT_AVALON_UART_RTS_LIMIT_OFF ((ALT_AVALON_UART_BUF_LEN*3)/4)# define ALT_AVALON_UART_RTS_LIMIT_ON ((ALT_AVALON_UART_BUF_LEN*2)/4)

.. in altera_avalon_uart.c

int alt_avalon_uart_read (alt_fd* fd, char* ptr, int len)

{

..

..

/*

* Ensure that interrupts are enabled, so that the circular buffer can

* re-fill.

*/

context = alt_irq_disable_all ();

dev->ctrl |= ALTERA_AVALON_UART_CONTROL_RRDY_MSK;

// !TF calculate number of bytes in buffer

if(dev->rx_end>=dev->rx_start) {

numbytes=dev->rx_end-dev->rx_start;

}

else {

numbytes=ALT_AVALON_UART_BUF_LEN-(dev->rx_start-dev->rx_end);

}

// set RTS if RTS_ON LIMIT is reached

if(numbytes<ALT_AVALON_UART_RTS_LIMIT_ON) {

dev->ctrl |= ALTERA_AVALON_UART_CONTROL_RTS_MSK;

}

// TF!

IOWR_ALTERA_AVALON_UART_CONTROL(dev->base, dev->ctrl);

alt_irq_enable_all (context);

/* Return the number of bytes read */

return count;

}

static void alt_avalon_uart_rxirq (alt_avalon_uart_dev* dev,

alt_u32 status)

{

..

..

..

/*

* If the cicular buffer was full, disable interrupts. Interrupts will be

* re-enabled when data is removed from the buffer.

*/

// !TF calculate number of bytes in buffer

if(dev->rx_end>=dev->rx_start) {

numbytes=dev->rx_end-dev->rx_start;

}

else {

numbytes=ALT_AVALON_UART_BUF_LEN-(dev->rx_start-dev->rx_end);

}

// clear RTS if RTS_OFF_LIMIT is reached

if(numbytes>ALT_AVALON_UART_RTS_LIMIT_OFF) {

dev->ctrl &= ~ALTERA_AVALON_UART_CONTROL_RTS_MSK;

}

// TF!

if (next == dev->rx_start)

{

dev->ctrl &= ~ALTERA_AVALON_UART_CONTROL_RRDY_MSK;

// !TF

//dev->ctrl &= ~ALTERA_AVALON_UART_CONTROL_RTS_MSK;

// TF!

IOWR_ALTERA_AVALON_UART_CONTROL(dev->base, dev->ctrl);

}

}

//############################################################################

int terminal_driver_set_flowcontrol(BYTE flowctrl) {

alt_fd* fd;

alt_avalon_uart_dev* dev; // pointer to uart device

if(fdterm<0) return -1;

// see alt_ioctrl.c

fd = (fdterm < 0) ? NULL : &alt_fd_list[fdterm];

if (fd) {

dev=(alt_avalon_uart_dev*)fd->dev;

if(flowctrl) {

dev->flags|=ALT_AVALON_UART_FC;

}

else {

dev->flags&=~ALT_AVALON_UART_FC;

}

return 0;

}

return -1;

}

I open device uart in non blocking mode:

static int fdterm; // FILEDESCRIPTOR RETURNED BY OPEN

..

fdterm = open("/dev/uart1", O_RDWR | O_NONBLOCK | O_NOCTTY);

..

reading is done by

..

res=read(fdterm,uart1_tempbuff,sizeof(uart1_tempbuff)-1);

if(res>0) {

... we have received some bytes

}

CTS can be set by function "terminal_driver_set_flowcontrol"