From bc163529ee6f2aa8ba3ea60047a8471b6d81e1c9 Mon Sep 17 00:00:00 2001
From: Robin Krens <robin@robinkrens.nl>
Date: Sun, 14 Jul 2019 00:13:52 +0800
Subject: [PATCH] basic uart functionality (not tested)

---
 include/mmap.h | 28 +++++++++++-----------------
 main.c         |  3 ++-
 systick.c      |  3 ++-
 uart.c         | 39 +++++++++++++++++++++++++++------------
 4 files changed, 42 insertions(+), 31 deletions(-)

diff --git a/include/mmap.h b/include/mmap.h
index 7caee1d..604579b 100644
--- a/include/mmap.h
+++ b/include/mmap.h
@@ -21,25 +21,19 @@
 
 
 /* SYSTEM CONTROL REGISTER */
-#define SYSCTRL_RCC ((volatile unsigned long *)(0x400FE060))
+#define SYSCTRL_RCC ((volatile unsigned long *)(0x40021000))
+#define RCC_APB2ENR ((volatile unsigned long *)(0x40021018)) // register to enable USART1
+
 #define SYSCTRL_RIS ((volatile unsigned long *)(0x400FE050))
 #define SYSCTRL_RCGC1 ((volatile unsigned long *)(0x400FE104))
 #define SYSCTRL_RCGC2 ((volatile unsigned long *)(0x400FE108))
 #define GPIOPA_AFSEL ((volatile unsigned long *)(0x40004420))
 
-/* USART REGISTERS */
-#define UART0_DATA ((volatile unsigned long *)(0x4000C000))
-#define UART0_FLAG ((volatile unsigned long *)(0x4000C018))
-#define UART0_IBRD ((volatile unsigned long *)(0x4000C024))
-#define UART0_FBRD ((volatile unsigned long *)(0x4000C028))
-#define UART0_LCRH ((volatile unsigned long *)(0x4000C02C))
-#define UART0_CTRL ((volatile unsigned long *)(0x4000C030))
-#define UART0_RIS ((volatile unsigned long *)(0x4000C03C))
-
-#define UART1_DATA ((volatile unsigned long *)(0x4000D000))
-#define UART1_FLAG ((volatile unsigned long *)(0x4000D018))
-#define UART1_IBRD ((volatile unsigned long *)(0x4000D024))
-#define UART1_FBRD ((volatile unsigned long *)(0x4000D028))
-#define UART1_LCRH ((volatile unsigned long *)(0x4000D02C))
-#define UART1_CTRL ((volatile unsigned long *)(0x4000D030))
-#define UART1_RIS ((volatile unsigned long *)(0x4000D03C))
+#define GPIOA_CRH ((volatile unsigned long *)(0x40010804))
+#define AFIO_EVCR ((volatile unsigned long *)(0x40010000))
+
+#define USART1_SR ((volatile unsigned long *)(0x40013800))
+#define USART1_DR ((volatile unsigned long *)(0x40013804))
+#define USART1_BRR ((volatile unsigned long *)(0x40013808))
+#define USART1_CR1 ((volatile unsigned long *)(0x4001380C))
+#define USART1_CR3 ((volatile unsigned long *)(0x40013814))
diff --git a/main.c b/main.c
index 58e4771..5453cbd 100644
--- a/main.c
+++ b/main.c
@@ -41,11 +41,12 @@ int strlen(const char *str)
 
 void main()
 {
-	//uart_init();
 	//uart_puts("LOADING SYSTEM...\n");
 
 	ivt_init();
+	uart_init();
 	systick_init();
+	uart_puts("WOGSYS LOADING...");
 //	asm("cpsie i"); // enable irq , cpsied f (disable faukts(
 
 	// loop
diff --git a/systick.c b/systick.c
index b9c8756..777d04d 100644
--- a/systick.c
+++ b/systick.c
@@ -7,7 +7,8 @@
 
 void * systick_handler() {
 
-	*RANDOM_ADDR = (volatile uint32_t) 0x10101010 ;
+//	*RANDOM_ADDR = (volatile uint32_t) 0x10101010 ;
+//	uart_puts("TEST");
 }
 
 void systick_init() {
diff --git a/uart.c b/uart.c
index bfef4b4..20a8d5e 100644
--- a/uart.c
+++ b/uart.c
@@ -6,10 +6,25 @@
 
 void uart_init() {
 
-/* To use the UARTs, the peripheral clock must be enabled by setting the UART0, UART1, or UART2
-bits in the RCGC1 register. (section 12.4: Initialization and Configuration */
+	// enable clock to UART1
+	*RCC_APB2ENR = 0x4005;
+	*GPIOA_CRH = 0x444444D4;
+	*AFIO_EVCR = 0x89;
+	
+	*USART1_CR1 = (0 << 13); // disable control register
+	*USART1_CR3 = 0xC0;
+
+	/* baud rate 9600 
+	 * 115200 = 8MHz / (16 * USARTDIV)
+	 * USARTDIV = 4.34
+	 * FRACTION: 16 x 0.34 = 0d5.44 0d5 -> 0x5
+	 * MANTISSA: 0d4.34 0d4 -> 0x4 
+	 * USART_BRR = 0x45*/
+
+	*USART1_BRR = 0x00000045;
 
-*SYSCTRL_RCGC1 = *SYSCTRL_RCGC1 | 0x0003;
+	/* parity = 8 bit, UART1 enabled, TX and RX enabled, interrupts enabled */
+	*USART1_CR1 = (volatile uint32_t) 0x000030AC; 
 
 /* 
  * Configure UART0:
@@ -22,7 +37,7 @@ bits in the RCGC1 register. (section 12.4: Initialization and Configuration */
 
 /* TODO: bitrate: How fast is CPU running?*/
 
-*UART0_CTRL = 0;
+/* *UART0_CTRL = 0;
 *UART0_IBRD = 27; 
 *UART0_FBRD = 9;
 *UART0_LCRH = 0x60; 
@@ -33,19 +48,19 @@ bits in the RCGC1 register. (section 12.4: Initialization and Configuration */
 *UART1_FBRD = 9;
 *UART1_LCRH = 0x60; 
 *UART1_CTRL = 0x301;
-
+*/
 
 }
 
 extern void uart_putc(unsigned char ch) {
 	
-	if (ch == '\n') {
-		while ((*UART0_FLAG & 0x8)); // busy bit
-		*UART0_DATA = 0x0D; // return line
-	}
-	
-	while ((*UART0_FLAG & 0x8)); // busy bit
-	*UART0_DATA = ch;
+//	if (ch == '\n') {
+//		while ((*UART1_DR & 0x8)); // busy bit
+//		*USART1_DR = 0x0D; // return line
+//	}
+//	
+//	while ((*UART0_FLAG & 0x8)); // busy bit
+	*USART1_DR = ch;
 }
 
 extern void uart_puts(unsigned char *str)
-- 
2.7.4