#define GPIO_FUNC_SEL0 0x80000018 /* GPIO 15 - 0; 2 bit blocks */ #define BASE_UART1 0x80005000 #define UART1_CON 0x80005000 #define UART1_STAT 0x80005004 #define UART1_DATA 0x80005008 #define UR1CON 0x8000500c #define UT1CON 0x80005010 #define UART1_CTS 0x80005014 #define UART1_BR 0x80005018 #include "embedded_types.h" #include "isr.h" __attribute__ ((section ("startup"))) void main(void) { /* Restore UART regs. to default */ /* in case there is still bootloader state leftover */ *(volatile uint32_t *)UART1_CON = 0x0000c800; /* mask interrupts, 16 bit sample --- helps explain the baud rate */ /* INC = 767; MOD = 9999 works: 115200 @ 24 MHz 16 bit sample */ #define INC 767 #define MOD 9999 *(volatile uint32_t *)UART1_BR = INC<<16 | MOD; /* see Section 11.5.1.2 Alternate Modes */ /* you must enable the peripheral first BEFORE setting the function in GPIO_FUNC_SEL */ /* From the datasheet: "The peripheral function will control operation of the pad IF */ /* THE PERIPHERAL IS ENABLED. */ *(volatile uint32_t *)UART1_CON = 0x00000003; /* enable receive and transmit */ *(volatile uint32_t *)GPIO_FUNC_SEL0 = ( (0x01 << (14*2)) | (0x01 << (15*2)) ); /* set GPIO15-14 to UART (UART1 TX and RX)*/ uint8_t c; while(1) { // *(volatile uint32_t *)UART1_DATA = (uint8_t)'U'; if(*(volatile uint32_t*)UR1CON > 0) { /* Receive buffer isn't empty */ /* read a byte and write it to the transmit buffer */ c = *(volatile uint32_t *)UART1_DATA; *(volatile uint32_t *)UART1_DATA = c; } }; }