Add Blinky stm32 example

.gitignore

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+zig-*

blinky-stm32f4/README.md

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+# STM32 Blinky
+
+This is an example project for getting started with microzig
+on STM32. I used an F407 discovery board, but it should work
+with any F4XX based board.

blinky-stm32f4/build.zig

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+const std = @import("std");
+const microzig = @import("microzig/src/main.zig");
+
+pub fn build(b: *std.build.Builder) void {
+    const backing = .{
+        .chip = microzig.chips.stm32f407vg
+    };
+    var elf = microzig.addEmbeddedExecutable(
+        b,
+        "firmware.elf",
+        "src/main.zig",
+        backing,
+        .{},
+    );
+
+    elf.setBuildMode(.ReleaseSmall);
+    elf.install();
+
+    const bin = b.addInstallRaw(elf.inner, "firmware.bin", .{});
+    const bin_step = b.step("bin", "Generate binary file to be flashed");
+    bin_step.dependOn(&bin.step);
+
+    const flash_cmd = b.addSystemCommand(&[_][]const u8{
+        "st-flash",
+        "write",
+        b.getInstallPath(bin.dest_dir, bin.dest_filename),
+        "0x8000000",
+    });
+
+    flash_cmd.step.dependOn(&bin.step);
+    const flash_step = b.step("flash", "Flash and run the app on your STM32 device");
+    flash_step.dependOn(&flash_cmd.step);
+
+    b.default_step.dependOn(&elf.inner.step);
+    b.installArtifact(elf.inner);
+}

blinky-stm32f4/microzig

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+/home/connor/workspace/connorrigby/underglow-controller-ng/firmware/microzig/

blinky-stm32f4/src/main.zig

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+const microzig = @import("microzig");
+const chip = microzig.chip;
+const regs = chip.registers;
+const cpu = microzig.cpu;
+
+// The LED PIN we want to use
+const PA1 = chip.parsePin("PA1");
+
+pub fn main() !void {
+    // above can also be accomplished with microzig with:
+    chip.gpio.setOutput(PA1);
+
+    while (true) {
+        // Read the current state of the gpioa register.
+        var gpioa_state = regs.GPIOA.ODR.read();
+
+        // we can use this to invert the current state easily
+        regs.GPIOA.ODR.modify(.{ .ODR1 = ~gpioa_state.ODR1 });
+
+        // Burn CPU cycles to delay the LED blink
+        var i: u32 = 0;
+        while (i < 600000) : (i += 1)
+            cpu.nop();
+    }
+}