add uart example (#266)

Co-authored-by: RecursiveError <[email protected]>
Co-authored-by: Felix Queißner <[email protected]>

examples/raspberrypi/rp2xxx/build.zig

@@ -12,7 +12,8 @@ const rp2040_only_examples = [_]Example{
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_random", .file = "src/rp2040_only/random.zig" },
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_spi-host", .file = "src/rp2040_only/spi_host.zig" },
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_squarewave", .file = "src/rp2040_only/squarewave.zig" },
-    .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_uart", .file = "src/rp2040_only/uart.zig" },
+    .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_uart_echo", .file = "src/rp2040_only/uart_echo.zig" },
+    .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_uart_log", .file = "src/rp2040_only/uart_log.zig" },
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_usb-hid", .file = "src/rp2040_only/usb_hid.zig" },
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_usb-cdc", .file = "src/rp2040_only/usb_cdc.zig" },
     .{ .target = rp2xxx.boards.raspberrypi.pico, .name = "pico_ws2812", .file = "src/rp2040_only/ws2812.zig" },

examples/raspberrypi/rp2xxx/src/rp2040_only/uart_echo.zig

@@ -0,0 +1,41 @@
+const std = @import("std");
+const microzig = @import("microzig");
+
+const rp2040 = microzig.hal;
+const uart = rp2040.uart;
+const gpio = rp2040.gpio;
+const time = rp2040.time;
+const clocks = rp2040.clocks;
+
+const echo_uart = uart.instance.num(0);
+const baud_rate = 115200;
+const uart_tx_pin = gpio.num(0);
+const uart_rx_pin = gpio.num(1);
+
+pub fn main() !void {
+    inline for (&.{ uart_tx_pin, uart_rx_pin }) |pin| {
+        pin.set_function(.uart);
+    }
+
+    echo_uart.apply(.{
+        .baud_rate = baud_rate,
+        .clock_config = rp2040.clock_config,
+        //.parity = .none,
+        //.stop_bits = .one,
+        //.flow_control = .none
+    });
+
+    var data: [1]u8 = .{0};
+    while (true) {
+        //read one byte, timeout disabled
+        echo_uart.read_blocking(&data, null) catch {
+            echo_uart.clear_errors(); //You need to clear UART errors before making a new transaction
+            continue;
+        };
+
+        //tries to write one byte with 100ms timeout
+        echo_uart.write_blocking(&data, time.Duration.from_ms(100)) catch {
+            echo_uart.clear_errors();
+        };
+    }
+}