Diff: main.cpp

Revision:

0:e637d54ba0a3

Child:

1:65c259961c26

diff -r 000000000000 -r e637d54ba0a3 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jul 21 19:23:35 2019 +0000
@@ -0,0 +1,95 @@
+#include <mbed.h>
+
+// Board: NUCLEO-F303RE.
+// -
+
+// We shall write to PA5 where the LED is..
+// Info: LEDs:
+//      https://www.st.com/resource/en/user_manual/dm00105823.pdf (UM1724: STM32 Nucleo-64 boards (MB1136))
+// Info: Talking to ports:
+//      https://developer.arm.com/tools-and-software/embedded/legacy-tools/ds-5-development-studio/resources/tutorials/accessing-memory-mapped-peripherals
+// Info: #defines : 
+//      https://raw.githubusercontent.com/ARMmbed/mbed-os/master/targets/TARGET_STM/TARGET_STM32F3/TARGET_STM32F303xE/device/stm32f303xe.h
+// Reference manual:
+//      https://www.st.com/resource/en/reference_manual/dm00043574.pdf
+// -
+// We 'll need the MODER (port mode) register (see ^reference manual) and the ODR (output data register).
+// Register addresses are calculated taking the GPIOA base address (found in the reference manual) and adding the appropriate register's offset to it.
+// -
+// Note:
+//      I was unsuccessfull in the following:
+//
+//      #define ODR ((volatile unsigned short*) (GPIOA + 0x14)
+// -
+
+#define MODER   ((volatile unsigned int*)   0x48000000)
+// 32 bits.
+// We 'll set pins 11,10 set to 0,1.
+// -
+
+#define ODR     ((volatile unsigned short*) 0x48000014)
+// 16 bits.
+// We 'll write at pin 5.
+// -
+
+// More FUN (dwarf fortress reference).
+// -
+#define OTYPER      ((volatile unsigned short*) (0x48000004))
+#define PUPDR       ((volatile unsigned int*)   (0x4800000C))
+#define BSRR        ((volatile unsigned int*)   (0x48000018))
+#define LCKR        ((volatile unsigned int*)   (0x4800001C))
+#define AFRL        ((volatile unsigned int*)   (0x48000020))
+
+void set_bit_as_output ()
+{
+    // Set to output.
+    // -
+    unsigned int moder = *MODER;
+    moder |= 0x00000400U;
+    moder &= 0xFFFFF7FFU;
+    // ^ Write 0,1 to bits 11,10.
+    // -
+    *MODER = moder;
+}
+
+void toggle_bit ()
+{
+///*
+    static unsigned short state = 0;
+    state ^= 0x20;
+    *ODR = state;
+//*/
+/*
+    static bool state = false;
+    if (state)
+    {
+        *BSRR = 0x00200000U;
+    }
+    else
+    {
+        *BSRR = 0x00000020U;
+    }    
+    state = !state;
+*/
+}
+
+int main ()
+{
+    set_bit_as_output();
+    while (true)
+    {
+        toggle_bit();
+/*
+        printf("MODER  = 0x%X\n",  *MODER);
+        printf("OTYPER = 0x%X\n",  *OTYPER);
+        printf("PUPDR  = 0x%X\n",  *PUPDR);
+        printf("ODR    = 0x%hX\n", *ODR);
+        printf("LCKR   = 0x%X\n",  *LCKR);
+        printf("AFRL   = 0x%X\n",  *AFRL);
+        printf("\n");
+*/
+        wait(0.65);
+        // ^ : https://os.mbed.com/docs/mbed-os/v5.13/apis/wait.html
+        // -
+    }
+}
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