Altera DE1-SoC - Page 12

DE1-SOC COMPUTER SYSTEM WITH NIOS II For Quartus II 15.0
/* function prototypes */
void put_jtag(char);
char get_jtag(void);
/********************************************************************************
* This program demonstrates use of the JTAG UART port in the DE1-SoC Computer
* It performs the following:
* 1. sends a text string to the JTAG UART
* 2. reads and echos character data from/to the JTAG UART
********************************************************************************/
int main(void)
{
char text_string[] = "\nJTAG UART example code\n> \0";
char *str, c;
/* print a text string */
for (str = text_string; *str != 0; ++str)
put_jtag (*str);
/* read and echo characters */
while (1)
{
c = get_jtag ( );
if (c != ’\0’)
put_jtag (c);
}
}
/********************************************************************************
* Subroutine to send a character to the JTAG UART
********************************************************************************/
void put_jtag( char c )
{
volatile int * JTAG_UART_ptr = (int *) 0xFF201000; // JTAG UART address
int control;
control = *(JTAG_UART_ptr + 1); // read the JTAG_UART control register
if (control & 0xFFFF0000) // if space, echo character, else ignore
*(JTAG_UART_ptr) = c;
}
Figure 12. An example of C code that uses the JTAG UART (Part a).
12 Altera Corporation - University Program
2015