Implement blinking LED

src/gpio.rs

@@ -0,0 +1,68 @@
+use crate::{
+    delay,
+    uart::{self},
+};
+
+const GPFSEL4: u32 = 0x3F20_0010; //GPIO 40-49
+const GPPUD: u32 = 0x3F20_0094;
+const GPPUD_CLK: u32 = 0x3F20_0098; // GPIO 32-53
+
+unsafe fn set_gpio47_to_output() {
+    let value: u32 = 0b001 << 21;
+
+    core::ptr::write_volatile(GPFSEL4 as *mut u32, value);
+}
+
+unsafe fn enable_pull_up() {
+    let value: u32 = 0b10;
+
+    core::ptr::write_volatile(GPPUD as *mut u32, value);
+}
+
+unsafe fn enable_pull_down() {
+    let value: u32 = 0b01;
+
+    core::ptr::write_volatile(GPPUD as *mut u32, value);
+}
+
+unsafe fn disable_GPPUD() {
+    core::ptr::write_volatile(GPPUD as *mut u32, 0);
+}
+
+unsafe fn enable_clock_gpio47() {
+    let value: u32 = 0b1 << 13;
+
+    core::ptr::write_volatile(GPPUD as *mut u32, value);
+}
+
+unsafe fn disable_GPPUD_CLK() {
+    core::ptr::write_volatile(GPPUD as *mut u32, 0);
+}
+
+pub fn pull_up_gpio47() {
+    unsafe {
+        uart::print("Pull Up\n");
+        set_gpio47_to_output();
+        enable_pull_up();
+        // Wait 150 cycles
+        delay(150);
+        enable_clock_gpio47();
+        delay(150);
+        disable_GPPUD();
+        disable_GPPUD_CLK();
+    }
+}
+
+pub fn pull_down_gpio47() {
+    unsafe {
+        uart::print("Pull Down\n");
+        set_gpio47_to_output();
+        enable_pull_down();
+        // Wait 150 cycles
+        delay(150);
+        enable_clock_gpio47();
+        delay(150);
+        disable_GPPUD();
+        disable_GPPUD_CLK();
+    }
+}