Fix and test uart_echo for rp2350

examples/raspberrypi/rp2xxx/build.zig

@@ -20,7 +20,6 @@ pub fn build(b: *std.Build) void {
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_pwm", .file = "src/rp2040_only/pwm.zig" },
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_random", .file = "src/rp2040_only/random.zig" },
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_rtc", .file = "src/rp2040_only/rtc.zig" },
-        .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_uart-echo", .file = "src/rp2040_only/uart_echo.zig" },
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_usb-hid", .file = "src/rp2040_only/usb_hid.zig" },
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_multicore", .file = "src/rp2040_only/blinky_core1.zig" },
         .{ .target = mb.ports.rp2xxx.boards.raspberrypi.pico, .name = "pico_hd44780", .file = "src/rp2040_only/hd44780.zig" },
@@ -38,6 +37,7 @@ pub fn build(b: *std.Build) void {
     };
 
     const chip_agnostic_examples: []const ChipAgnosticExample = &.{
+        .{ .name = "uart-echo", .file = "src/uart_echo.zig" },
         .{ .name = "uart-log", .file = "src/uart_log.zig" },
         .{ .name = "spi-master", .file = "src/spi_master.zig" },
         .{ .name = "spi-slave", .file = "src/spi_slave.zig" },

examples/raspberrypi/rp2xxx/src/uart_echo.zig

@@ -0,0 +1,45 @@
+const std = @import("std");
+const microzig = @import("microzig");
+const time = microzig.drivers.time;
+
+const rp2xxx = microzig.hal;
+const gpio = rp2xxx.gpio;
+const clocks = rp2xxx.clocks;
+
+const led = gpio.num(25);
+const uart = rp2xxx.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 {
+    led.set_function(.sio);
+    led.set_direction(.out);
+    led.put(1);
+    inline for (&.{ uart_tx_pin, uart_rx_pin }) |pin| {
+        pin.set_function(.uart);
+    }
+
+    uart.apply(.{
+        .baud_rate = baud_rate,
+        .clock_config = rp2xxx.clock_config,
+    });
+
+    var data: [1]u8 = .{0};
+    while (true) {
+        // Read one byte, timeout disabled
+        uart.read_blocking(&data, null) catch {
+            // You need to clear UART errors before making a new transaction
+            uart.clear_errors();
+            continue;
+        };
+
+        //tries to write one byte with 100ms timeout
+        uart.write_blocking(&data, time.Duration.from_ms(100)) catch {
+            uart.clear_errors();
+        };
+        // Toggle the led every time we think we've received a character so we
+        // know something is going on.
+        led.toggle();
+    }
+}