Implements input, pull up/down and uart routing.

build.zig

@@ -3,7 +3,7 @@ const Builder = std.build.Builder;
 const Pkg = std.build.Pkg;
 const comptimePrint = std.fmt.comptimePrint;
 
-const microzig = @import("deps/microzig/src/main.zig");
+pub const microzig = @import("deps/microzig/src/main.zig");
 
 const chip_path = comptimePrint("{s}/src/rp2040.zig", .{root()});
 const board_path = comptimePrint("{s}/src/raspberry_pi_pico.zig", .{root()});

src/hal/gpio.zig

@@ -97,6 +97,14 @@ pub inline fn toggle(comptime gpio: u32) void {
     regs.SIO.GPIO_OUT_XOR.raw = (1 << gpio);
 }
 
+pub inline fn read(comptime gpio: u32) u1 {
+    const mask = 1 << gpio;
+    return if ((regs.SIO.GPIO_IN.raw & mask) != 0)
+        1
+    else
+        0;
+}
+
 pub inline fn setFunction(comptime gpio: u32, function: Function) void {
     const pad_bank_reg = comptime std.fmt.comptimePrint("GPIO{}", .{gpio});
     @field(regs.PADS_BANK0, pad_bank_reg).modify(.{

src/hal/pins.zig

@@ -50,11 +50,15 @@ pub const Pin = enum {
         // schmitt trigger
         // hysteresis
 
-        pub fn getDirection(config: Configuration) gpio.Direction {
+        pub fn getDirection(comptime config: Configuration) gpio.Direction {
             return if (config.direction) |direction|
                 direction
-            else if (config.function.isPwm())
+            else if (comptime config.function.isPwm())
                 .out
+            else if (comptime config.function.isUartTx())
+                .out
+            else if (comptime config.function.isUartRx())
+                .in
             else
                 @panic("TODO");
         }
@@ -157,6 +161,24 @@ pub const Function = enum {
         };
     }
 
+    pub fn isUartTx(function: Function) bool {
+        return switch (function) {
+            .UART0_TX,
+            .UART1_TX,
+            => true,
+            else => false,
+        };
+    }
+
+    pub fn isUartRx(function: Function) bool {
+        return switch (function) {
+            .UART0_RX,
+            .UART1_RX,
+            => true,
+            else => false,
+        };
+    }
+
     pub fn pwmSlice(comptime function: Function) u32 {
         return switch (function) {
             .PWM0_A, .PWM0_B => 0,
@@ -280,7 +302,7 @@ pub fn GPIO(comptime num: u5, comptime direction: gpio.Direction) type {
 
             pub inline fn read(self: @This()) u1 {
                 _ = self;
-                @compileError("TODO");
+                return gpio.read(gpio_num);
             }
         },
         .out => struct {
@@ -424,6 +446,21 @@ pub const GlobalConfiguration = struct {
         if (output_gpios != 0)
             regs.SIO.GPIO_OE_SET.raw = output_gpios;
 
+        if (input_gpios != 0) {
+            inline for (@typeInfo(GlobalConfiguration).Struct.fields) |field|
+                if (@field(config, field.name)) |pin_config| {
+                    const pull = pin_config.pull orelse continue;
+                    if (comptime pin_config.getDirection() != .in)
+                        @compileError("Only input pins can have pull up/down enabled");
+
+                    const gpio_regs = @field(regs.PADS_BANK0, field.name);
+                    gpio_regs.modify(comptime .{
+                        .PUE = @boolToInt(pull == .up),
+                        .PDE = @boolToInt(pull == .down),
+                    });
+                };
+        }
+
         // TODO: pwm initialization
 
         // fields in the Pins(config) type should be zero sized, so we just