nRF5x: Add basic timer support (#560)

Author: Grazfather

examples/nordic/nrf5x/src/blinky.zig

@@ -1,27 +1,22 @@
 const std = @import("std");
 const microzig = @import("microzig");
 const board = microzig.board;
-
-fn delay(cycles: u32) void {
-    var i: u32 = 0;
-    while (i < cycles) : (i += 1) {
-        std.mem.doNotOptimizeAway(i);
-    }
-}
+const nrf = microzig.hal;
+const time = nrf.time;
 
 pub fn main() !void {
     board.init();
 
     while (true) {
         board.led1.toggle();
-        delay(2000000);
+        time.sleep_ms(500);
 
         board.led1.toggle();
         board.led2.toggle();
-        delay(2000000);
+        time.sleep_ms(500);
 
         board.led2.toggle();
         board.led3.toggle();
-        delay(2000000);
+        time.sleep_ms(500);
     }
 }

port/nordic/nrf5x/src/hal.zig

@@ -2,9 +2,16 @@ const microzig = @import("microzig");
 
 pub const compatibility = @import("hal/compatibility.zig");
 pub const gpio = @import("hal/gpio.zig");
+pub const time = @import("hal/time.zig");
 pub const uart = @import("hal/uart.zig");
 // TODO: adc, timers, pwm, rng, rtc, spi, interrupts, i2c, wdt, wifi, nfc, bt, zigbee
 
+pub fn init() void {
+    time.init();
+}
+
 test "hal tests" {
     _ = gpio;
+    _ = time;
+    _ = uart;
 }

port/nordic/nrf5x/src/hal/time.zig

@@ -0,0 +1,41 @@
+///
+/// Basic timekeeping for the nRF5x series MCUs.
+///
+/// This module hogs TIMER0.
+/// It uses CC1 as the register to read the current count from.
+const std = @import("std");
+const microzig = @import("microzig");
+const time = microzig.drivers.time;
+
+const timer = microzig.chip.peripherals.TIMER0;
+const READ_INDEX = 1;
+
+var overflow_count: u32 = 0;
+
+pub fn init() void {
+    // Stop timer while we set it up
+    timer.TASKS_STOP.write(.{ .TASKS_STOP = .Trigger });
+    defer timer.TASKS_START.write(.{ .TASKS_START = .Trigger });
+
+    // Clear the time
+    timer.TASKS_CLEAR.write(.{ .TASKS_CLEAR = .Trigger });
+
+    timer.MODE.write(.{ .MODE = .Timer });
+    timer.BITMODE.write(.{ .BITMODE = .@"32Bit" });
+    // 16Mhz / 2^4 = 1MHz: us resolution
+    timer.PRESCALER.write(.{ .PRESCALER = 4 });
+}
+
+pub fn get_time_since_boot() time.Absolute {
+    timer.TASKS_CAPTURE[READ_INDEX].write(.{ .TASKS_CAPTURE = .Trigger });
+    return @enumFromInt(@as(u64, overflow_count) << 32 | timer.CC[READ_INDEX].raw);
+}
+
+pub fn sleep_ms(time_ms: u32) void {
+    sleep_us(time_ms * 1000);
+}
+
+pub fn sleep_us(time_us: u64) void {
+    const end_time = time.make_timeout_us(get_time_since_boot(), time_us);
+    while (!end_time.is_reached_by(get_time_since_boot())) {}
+}

port/nordic/nrf5x/src/hal/uart.zig

@@ -9,6 +9,7 @@ const types = microzig.chip.types;
 const UART_Regs = types.peripherals.UART0;
 
 const gpio = @import("gpio.zig");
+const time = @import("time.zig");
 
 var uart_logger: ?UART.Writer = null;
 
@@ -37,20 +38,18 @@ pub fn logFn(
     comptime format: []const u8,
     args: anytype,
 ) void {
-    const level_prefix = comptime level.asText();
-    // const level_prefix = comptime "[{}.{:0>6}] " ++ level.asText();
+    const level_prefix = comptime "[{}.{:0>6}] " ++ level.asText();
     const prefix = comptime level_prefix ++ switch (scope) {
         .default => ": ",
         else => " (" ++ @tagName(scope) ++ "): ",
     };
 
     if (uart_logger) |uart| {
-        // const current_time = time.get_time_since_boot();
-        // const seconds = current_time.to_us() / std.time.us_per_s;
-        // const microseconds = current_time.to_us() % std.time.us_per_s;
+        const current_time = time.get_time_since_boot();
+        const seconds = current_time.to_us() / std.time.us_per_s;
+        const microseconds = current_time.to_us() % std.time.us_per_s;
 
-        // uart.print(prefix ++ format ++ "\r\n", .{ seconds, microseconds } ++ args) catch {};
-        uart.print(prefix ++ format ++ "\r\n", args) catch {};
+        uart.print(prefix ++ format ++ "\r\n", .{ seconds, microseconds } ++ args) catch {};
     }
 }