3 files changed, 59 insertions, 4 deletions

diff --git a/02-usart/src/main.c b/02-usart/src/main.c
index 5f45e0b..b4f7dd7 100644
--- a/02-usart/src/main.c
+++ b/02-usart/src/main.c
@@ -1,4 +1,7 @@
 
+#include "string.h"
+#include "mem.h"
+#include "dma.h"
 #include "arch.h"
 #include "clock.h"
 #include "delay.h"
@@ -8,7 +11,7 @@
 
 volatile uint32_t delay_amt = 20000000 / 4;
 
-int enable_usart2(uint32_t baud_rate)
+int setup_usart2(uint32_t baud_rate)
 {
   __IO gpio_port_t* port_a = enable_gpio(GPIO_PORT_A);
   enable_hsi(&RCC, true);
@@ -36,7 +39,6 @@ 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 | USART_ENABLE_RX);
 }
 
 int enable_usart1(uint32_t baud_rate)
@@ -88,10 +90,34 @@ int main()
   /* Enable a higher clock frequency. */
   set_system_clock_MHz(80);
 
-  enable_usart2(115200);
+  setup_usart2(115200);
+
+
+  char* into = (char*) (SRAM1_BASE + 50);
+  const char* hello = "Hello, Chester Cheeto!\r\n";
+  int len = strlen(hello);
+  memcpy(into, hello, len + 1);
+
+  usart_enable_dma(&USART2, USART_ENABLE_TX);
+  usart_set_enabled(&USART2, USART_ENABLE_TX | USART_ENABLE_RX);
+
+  pin_on(pin3);
+
+  RCC.ahb1en_bf.dma1en = 1; /* Enable DMA1 Clock. */
+  DMA1.csel_bf.c7s = 0x2; /* Select USART2_TX for the sel. */
+  DMA1.channel_config[6].cc_r = 0;
+  DMA1.channel_config[6].cc_bf.dir = READ_FROM_MEMORY;
+  DMA1.channel_config[6].cc_bf.minc = 1;
+  DMA1.channel_config[6].cc_bf.pl = DMA_PRIORITY_LEVEL_VERY_HIGH;
+  DMA1.channel_config[6].cndt_bf.ndt = len;
+  DMA1.channel_config[6].cpa_r = ptr2reg(&USART2.td_r);
+  DMA1.channel_config[6].cma_r = ptr2reg(into);
+
+  USART2.ic_bf.tccf = 1;
+  DMA1.channel_config[6].cc_bf.en = 1;
 
   pin_on(pin3);
-  usart_transmit_str_sync(&USART2, "Hello, World\n");
+  // usart_transmit_str_sync(&USART2, into);
   for(;;);
 }
 
diff --git a/02-usart/src/mem.c b/02-usart/src/mem.c
new file mode 100644
index 0000000..5772bdc
--- /dev/null
+++ b/02-usart/src/mem.c
@@ -0,0 +1,11 @@
+#include "mem.h"
+#include "common.h"
+
+void memcpy_(void* dest, const void* src, size_t len)
+{
+  uint8_t* dest_ = (uint8_t*) dest;
+  uint8_t* src_ = (uint8_t*) src;
+
+  while ((len--) > 0)
+    *(dest_ ++) = *(src_ ++);
+}
diff --git a/02-usart/src/usart.c b/02-usart/src/usart.c
index 42297a8..d4073d0 100644
--- a/02-usart/src/usart.c
+++ b/02-usart/src/usart.c
@@ -78,3 +78,21 @@ void usart_transmit_str_sync(__IO usart_t* usart, const char* str)
     usart_transmit_byte_sync(usart, *(str ++));
   }
 }
+
+void usart_enable_dma(__IO usart_t* usart, usart_enable_t enabled)
+{
+  switch(enabled) {
+    case USART_ENABLE_DISABLED:
+      usart->c3_bf.dmar = 0;
+      usart->c3_bf.dmat = 0;
+      break;
+
+    case USART_ENABLE_TX:
+      usart->c3_bf.dmat = 1;
+      break;
+
+    case USART_ENABLE_RX:
+      usart->c3_bf.dmar = 1;
+      break;
+  };
+}