examples/soc_ecp5_evn/firmware.c

#include <stdint.h>

#define LED (*(volatile uint32_t*)0x02000000)

#define reg_uart_clkdiv (*(volatile uint32_t*)0x02000004)
#define reg_uart_data (*(volatile uint32_t*)0x02000008)

void putchar(char c)
{
    if (c == '\n')
        putchar('\r');
    reg_uart_data = c;
}

void print(const char *p)
{
    while (*p)
        putchar(*(p++));
}

void delay() {
    for (volatile int i = 0; i < 250000; i++)
        ;
}

int main() {
    reg_uart_clkdiv = 416;
    while (1) {
        LED = 0xFF;
        print("hello world\n");
        delay();
        LED = 0x00;
        delay();
    }
}