Make firmware build and run

1 files changed, 43 insertions, 0 deletions

diff --git a/prototype/fw/src/main.c b/prototype/fw/src/main.c
index a6b265b..de920eb 100644
--- a/prototype/fw/src/main.c
+++ b/prototype/fw/src/main.c
@@ -2,7 +2,50 @@
 #include <global.h>
 
 int main(void) {
+
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
+    RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
+
+    GPIOA->MODER |= (2 << GPIO_MODER_MODER9_Pos);
+    GPIOA->AFR[1] = (7 << (9-8)*4);
+
+    SystemCoreClockUpdate();
+    int apb2_clock = SystemCoreClock / APB2_PRESC;
+    
+    int baudrate = 115200;
+
+    USART1->CR1 = USART_CR1_MME | USART_CR1_TE;
+    USART1->BRR = (apb2_clock + baudrate/2) / baudrate;
+    USART1->CR1 |= USART_CR1_UE;
+
+    char s[12] = {
+        '0', '0', '0', '0', '0',
+        ' ', 'T', 'E', 'S', 'T',
+        '\n', '\0'};
+    int line = 0;
+    char *c = s;
+    USART1->TDR = *(c++); /* Kick off transmission */
     while (23) {
+        if (USART1->ISR & USART_ISR_TXE) {
+            for (int i=0; i<100; i++)
+                asm volatile ("nop");
+            USART1->TDR = *(c++);
+            if (!*c) {
+                c = s;
+                line++;
+                int tmp = line;
+                tmp %= 100000;
+                s[0] = '0' + tmp/10000;
+                tmp %= 10000;
+                s[1] = '0' + tmp/1000;
+                tmp %= 1000;
+                s[2] = '0' + tmp/100;
+                tmp %= 100;
+                s[3] = '0' + tmp/10;
+                tmp %= 10;
+                s[4] = '0' + tmp;
+            }
+        }
     }
 }