simple uart enabled.

5 files changed, 82 insertions, 20 deletions

diff --git a/README.md b/README.md
index 5d97395..8630ab2 100644
--- a/README.md
+++ b/README.md
@@ -23,3 +23,8 @@ Requirements
 * st-flash -- This can be found [here](https://github.com/texane/stlink.git)
 * perl
 * Cross compiler for arm -- Mine is installed with prefix `arm-unknown-eabi-`.
+
+Resources
+---------
+
+Datasheet may be found [here](http://www.st.com/content/ccc/resource/technical/document/reference_manual/group0/b0/ac/3e/8f/6d/21/47/af/DM00151940/files/DM00151940.pdf/jcr:content/translations/en.DM00151940.pdf)
diff --git a/usart/include/common.h b/usart/include/common.h
index d88d82d..9d5c7cd 100644
--- a/usart/include/common.h
+++ b/usart/include/common.h
@@ -1,6 +1,8 @@
 #ifndef COMMON__H
 #define COMMON__H
 
+#include <stdint.h>
+
 /* Define __IO to be volatile if it's not already. */
 #ifndef __IO
 #define __IO volatile
@@ -15,4 +17,14 @@
 #define PACKED __attribute__((packed))
 #define BIT(n) (1 << (n))
 
+#define RESERVED_CONCAT_IMPL(x, y) x ## y
+#define RESERVED_MACRO_CONCAT(x, y) RESERVED_CONCAT_IMPL(x, y)
+#define RESERVED(n) \
+  bits_t RESERVED_MACRO_CONCAT(_r, __COUNTER__) :n
+  
+#define RESERVE(type) \
+  __IO type RESERVED_MACRO_CONCAT(_r, __COUNTER__)
+
+typedef uint32_t bits_t;
+
 #endif /* COMMON_H */
diff --git a/usart/include/usart.h b/usart/include/usart.h
index ebc5458..257aab6 100644
--- a/usart/include/usart.h
+++ b/usart/include/usart.h
@@ -18,7 +18,33 @@ typedef enum {
 
 typedef struct {
   /* USART configuration registers 0x04 - 0x0c. */
-  uint32_t c_r1;
+  union {
+    uint32_t c_r1;
+    struct {
+      bits_t ue:1;     /* UART enable */
+      bits_t uesm:1;   /* UART enabled in stop mode. */
+      bits_t re:1;     /* reciever enabled. */
+      bits_t te:1;     /* transmitter enabled. */
+      bits_t idleie:1; /* Idle interrupt enabled. */
+      bits_t rxneie:1; /* RXNEIE RXNE interrupt enable. */
+      bits_t tcie:1;
+      bits_t txeie:1;
+      bits_t peie:1;
+      bits_t ps:1;
+      bits_t pce:1;
+      bits_t wake:1;
+      bits_t m0:1;
+      bits_t mme:1;
+      bits_t cmie:1;
+      bits_t over8:1;
+      bits_t dedt:4;
+      bits_t deat:4;
+      bits_t rtoie:1;
+      bits_t eobie:1;
+      bits_t m1:1;
+      bits_t reserved:3;
+    } PACKED c1_bf;
+  };
   uint32_t c_r2;
   uint32_t c_r3;
 
@@ -73,10 +99,9 @@ typedef enum {
 } usart_parity_t;
 
 typedef enum {
-  USART_ENABLE_TX_RX    = 0x0d, /* 0b1101 */
-  USART_ENABLE_TX       = 0x09, /* 0b1001 */
-  USART_ENABLE_RX       = 0x05, /* 0b0101 */
-  USART_ENABLE_DISABLED = 0x00, /* 0b0000 */
+  USART_ENABLE_TX       = 0x02,
+  USART_ENABLE_RX       = 0x01,
+  USART_ENABLE_DISABLED = 0x00,
 } usart_enable_t;
 
 void usart_set_parity(__IO usart_t* usart, usart_parity_t parity);
@@ -97,6 +122,10 @@ void set_usart2_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src);
 
 void set_usart2_clock_enabled(__IO rcc_t* rcc, bool enable);
 
+void usart_transmit_bytes(
+    __IO usart_t* usart, const uint8_t* bytes, uint32_t n);
+
+void usart_transmit_str(__IO usart_t* usart, const char* str);
 
 
 #endif /* H__USART_ */
diff --git a/usart/src/main.c b/usart/src/main.c
index 5e33876..5af52ed 100644
--- a/usart/src/main.c
+++ b/usart/src/main.c
@@ -1,3 +1,4 @@
+
 #include "clock.h"
 #include "delay.h"
 #include "gpio.h"
@@ -34,7 +35,7 @@ int enable_usart2(uint32_t baud_rate)
   USART2.c_r3 = 0;
 
   usart_set_divisor(&USART2, 16000000 / baud_rate);
-  usart_set_enabled(&USART2, USART_ENABLE_TX_RX);
+  usart_set_enabled(&USART2, USART_ENABLE_TX | USART_ENABLE_RX);
 }
 
 int enable_usart1(uint32_t baud_rate)
@@ -82,12 +83,11 @@ int main()
   gpio_output_pin_t pin1 = set_gpio_pin_output(port_b, PIN_1);
 
   /* Enable a higher clock frequency. */
-  // set_system_clock_MHz(80);
+  set_system_clock_MHz(80);
 
-  enable_usart2(9600);
+  enable_usart2(115200);
 
   pin_on(pin3);
-  while (true) {
-    usart_transmit_byte(&USART2, 0x32);
-  }
+  usart_transmit_str(&USART2, "Hello, World\n");
+  for(;;);
 }
diff --git a/usart/src/usart.c b/usart/src/usart.c
index 23dbd95..eddfbe7 100644
--- a/usart/src/usart.c
+++ b/usart/src/usart.c
@@ -40,16 +40,15 @@ void usart_set_parity(__IO usart_t* usart, usart_parity_t parity)
 void usart_set_enabled(__IO usart_t* usart, usart_enable_t enabled)
 {
   uint32_t c_r1 = usart->c_r1;
-  /* Clear relevant bits. */
-  c_r1 &= ~USART_ENABLE_TX_RX;
 
-  /* Set TX/RX enabled, but not actually USART enabled. */
-  c_r1 |= (enabled & ~1);
-
-  /* Set usart enabled bit separately. */
-  c_r1 |= enabled & 1;
-
-  usart->c_r1 = c_r1;
+  if (!enabled) {
+    usart->c1_bf.ue = 0;
+  } else {
+    /* Set the rx enabled. */
+    usart->c1_bf.re = !!(enabled & USART_ENABLE_RX);
+    usart->c1_bf.te = !!(enabled & USART_ENABLE_TX);
+    usart->c1_bf.ue = 1;
+  }
 }
 
 void usart_transmit_byte(__IO usart_t* usart, uint8_t byte)
@@ -62,3 +61,20 @@ void usart_transmit_byte(__IO usart_t* usart, uint8_t byte)
   while (!(usart->is_r & BIT(7)))
     ;
 }
+
+void usart_transmit_bytes(__IO usart_t* usart, const uint8_t* bytes, uint32_t n)
+{
+  while (n --) {
+    usart_transmit_byte(usart, *(bytes ++));
+  }
+}
+
+void usart_transmit_str(__IO usart_t* usart, const char* str)
+{
+  while (*str) {
+    if (*str == '\n') {
+      usart_transmit_byte(usart, '\r');
+    }
+    usart_transmit_byte(usart, *(str ++));
+  }
+}