Altera Embedded Peripherals IP - Manual (Page 102)

Figure 9-8:
typedef struct altera_16550_uart_state_s
{
alt_dev dev;
void* base; /* The base address of the device */
alt_u32 clock;
alt_u32 FIFOMode
alt_u32 ctrl; /* Shadow value of the LSR register */
alt_u32 rx_start; /* Start of the pending receive data*/
volatile alt_u32 rx_end; /* End of the pending receive data */
volatile alt_u32 tx_start; /* Start of the pending transmitdata*/
alt_u32 tx_end; /* End ofthe pending transmit data */
alt_u32 freq; /* Current clock freq rate */
UartConfig config; /* Uart setting */
alt_u32 flags; /* Configuration flags */
ALT_FLAG_GRP (events) /* Event flags used for
* foreground/background in mult-
*threaded mode*/
ALT_SEM (read_lock) /* Semaphore used to control access
* to the read buffer in multi-
*threaded mode*/
ALT_SEM (write_lock) /* Semaphore used to control access
* to the write buffer in multi-
*threaded mode */
alt_u8 rx_buf[ALT_16550_UART_BUF_LEN]; /* The receive buffer */
alt_u8 tx_buf[ALT_16550_UART_BUF_LEN]; /* The transmit buffer */
} altera_16550_uart_state;
Driver Examples
Below is a simple test program to verify that the Altera 16550 UART driver support is functional.
The test reads, validates, and writes a modified baud rate, data bits, stop bits, parity bits to the UART
before attempting to write a character stream to it from UART0 to UART1 and vice verse (ping pong
test). This also tests the FIFO and FIFO-less mode as well as the HW flow control to ensure the IP is
functioning for FIFO and HWFC.
Prerequisites needed before running test:
• An instance of UART named "uart0" and another instance UART named "uart1"
• Both UARTs need to be connected in loopback in Quartus.
Additional coverage:
• Non-blocking UART support
• UART HAL driver
• HAL open/write support
The test will print "PASS: . . ." from the UART to indicate success.
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/termios.h>
#include <fcntl.h>
#include <string.h>
9-16 Driver Examples
UG-01085
2014.24.07
Altera Corporation 16550 UART
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