diff --git a/examples/gpio-demo/Cargo.toml b/examples/gpio-demo/Cargo.toml
index 1be821a60187d37d7476866ea9d07bc9a1d4cb5d..a92b871435bdaf59d98ca7eb6e5c87b43da3f99d 100644
--- a/examples/gpio-demo/Cargo.toml
+++ b/examples/gpio-demo/Cargo.toml
@@ -11,6 +11,7 @@ bl-soc = { path = "../..", features = ["bl808"] }
 base-address = "0.0.0"
 panic-halt = "0.2.0"
 embedded-hal = "1.0.0-rc.1"
+riscv = "0.10.1"
 
 [dependencies.bl-rom-rt]
 git = "https://gitee.com/rustsbi/bl-rom-rt"
diff --git a/examples/gpio-demo/src/main.rs b/examples/gpio-demo/src/main.rs
index baa8a36606f06d85d40e09834d3675013bd2374b..3b23472ca4757f4326a501fa7761dec7f26dd387 100644
--- a/examples/gpio-demo/src/main.rs
+++ b/examples/gpio-demo/src/main.rs
@@ -31,16 +31,12 @@ fn main() -> ! {
         if button_1_pressed && button_2_pressed {
             led.set_state(led_state).ok();
             led_state = !led_state;
-            for _ in 0..100_000 {
-                unsafe { core::arch::asm!("nop") }
-            }
+            unsafe { riscv::asm::delay(10_000) }
         } else if button_1_pressed {
             led.set_low().ok();
         } else if button_2_pressed {
             led.set_high().ok();
         }
-        for _ in 0..100_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(100_000) }
     }
 }
diff --git a/examples/i2c-demo/Cargo.toml b/examples/i2c-demo/Cargo.toml
index 069f7e528386da762915220ff1687adc9de7ee1e..52b8003895cbfb8f1a100974d2f27b5e6bc3b92a 100644
--- a/examples/i2c-demo/Cargo.toml
+++ b/examples/i2c-demo/Cargo.toml
@@ -11,6 +11,7 @@ bl-soc = { path = "../..", features = ["bl808"] }
 base-address = "0.0.0"
 panic-halt = "0.2.0"
 embedded-time = "0.12.1"
+riscv = "0.10.1"
 
 [dependencies.bl-rom-rt]
 git = "https://gitee.com/rustsbi/bl-rom-rt"
diff --git a/examples/i2c-demo/src/main.rs b/examples/i2c-demo/src/main.rs
index d11e49b32e91597ca4d7550192648159d72145a5..7a948eacffbcf1243509464da89bdc45f35fc8b5 100644
--- a/examples/i2c-demo/src/main.rs
+++ b/examples/i2c-demo/src/main.rs
@@ -7,14 +7,7 @@
 
 use base_address::Static;
 use bl_rom_rt::entry;
-use bl_soc::{
-    clocks::Clocks,
-    gpio::Pins,
-    i2c::I2c,
-    prelude::*,
-    uart::{BitOrder, Config, Parity, StopBits, UartMuxes, WordLength},
-    GLB, I2C, UART,
-};
+use bl_soc::{clocks::Clocks, gpio::Pins, i2c::I2c, prelude::*, uart::UartMuxes, GLB, I2C, UART};
 use embedded_time::rate::*;
 use panic_halt as _;
 
@@ -44,12 +37,7 @@ fn main() -> ! {
     let sig2 = uart_muxes.sig2.into_transmit::<0>();
     let sig3 = uart_muxes.sig3.into_receive::<0>();
 
-    let config = Config {
-        bit_order: BitOrder::LsbFirst,
-        parity: Parity::None,
-        stop_bits: StopBits::One,
-        word_length: WordLength::Eight,
-    };
+    let config = Default::defnault();
     let mut serial = uart0.freerun(config, 2000000.Bd(), ((tx, sig2), (rx, sig3)), &clocks);
     let mut led = gpio.io8.into_floating_output();
 
@@ -61,9 +49,7 @@ fn main() -> ! {
     writeln!(serial, "Hello Rust🦀!").ok();
     let mut buf = [0u8; 6];
     loop {
-        for _ in 0..100_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(100_000) };
         match i2c.read(SCREEN_ADDRESS, &mut buf) {
             Ok(_) => {
                 if buf[2] >> 4 == 8 {
diff --git a/examples/jtag-demo/Cargo.toml b/examples/jtag-demo/Cargo.toml
index acc10ccb39df33973ed2abb36466edaa1de61c4c..3f0a4c15445c8887c186e2f2d118c866fbd237b6 100644
--- a/examples/jtag-demo/Cargo.toml
+++ b/examples/jtag-demo/Cargo.toml
@@ -10,6 +10,7 @@ publish = false
 bl-soc = { path = "../..", features = ["bl808"] }
 base-address = "0.0.0"
 panic-halt = "0.2.0"
+riscv = "0.10.1"
 
 [dependencies.bl-rom-rt]
 git = "https://gitee.com/rustsbi/bl-rom-rt"
diff --git a/examples/jtag-demo/src/main.rs b/examples/jtag-demo/src/main.rs
index f194385af94cadf104c759e35e889700096c1be6..0b82f24e0e4a03262339ff7d86131b37b952143c 100644
--- a/examples/jtag-demo/src/main.rs
+++ b/examples/jtag-demo/src/main.rs
@@ -22,12 +22,8 @@ fn main() -> ! {
     let mut led = gpio.io8.into_floating_output();
     loop {
         led.set_low().ok();
-        for _ in 0..100_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(100_000) };
         led.set_high().ok();
-        for _ in 0..100_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(100_000) };
     }
 }
diff --git a/examples/pwm-demo/Cargo.toml b/examples/pwm-demo/Cargo.toml
index be79d20bbd01317e2dd3127caa2cd1e6d0225d2e..281c75d24ebb80074794a693bc55a6661f7643e3 100644
--- a/examples/pwm-demo/Cargo.toml
+++ b/examples/pwm-demo/Cargo.toml
@@ -11,6 +11,7 @@ bl-soc = { path = "../..", features = ["bl808"] }
 base-address = "0.0.0"
 panic-halt = "0.2.0"
 embedded-time = "0.12.1"
+riscv = "0.10.1"
 
 [dependencies.bl-rom-rt]
 git = "https://gitee.com/rustsbi/bl-rom-rt"
diff --git a/examples/pwm-demo/src/main.rs b/examples/pwm-demo/src/main.rs
index 98ec9dd4cfb0b4205626f31b109ea78965b3cd3e..53e99c14438134a07ab69ffbfe094aac4c1b8b28 100644
--- a/examples/pwm-demo/src/main.rs
+++ b/examples/pwm-demo/src/main.rs
@@ -43,25 +43,17 @@ fn main() -> ! {
     loop {
         for duty in 0..100 {
             led.set_duty_cycle(duty).ok();
-            for _ in 0..1_000 {
-                unsafe { core::arch::asm!("nop") }
-            }
+            unsafe { riscv::asm::delay(1_000) };
         }
         led.set_high().ok();
-        for _ in 0..100_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(100_000) };
         led.enable_pwm_output();
         for duty in (0..100).rev() {
             led.set_duty_cycle(duty).ok();
-            for _ in 0..1_000 {
-                unsafe { core::arch::asm!("nop") }
-            }
+            unsafe { riscv::asm::delay(1_000) };
         }
         led.set_low().ok();
-        for _ in 0..200_000 {
-            unsafe { core::arch::asm!("nop") }
-        }
+        unsafe { riscv::asm::delay(200_000) };
         led.enable_pwm_output();
     }
 }
diff --git a/examples/uart-demo/src/main.rs b/examples/uart-demo/src/main.rs
index fbe7aaa236f1295ea1ebe128c96cc9f39dc67285..9e78a8fdf8f31e5966412504617f458750e29940 100644
--- a/examples/uart-demo/src/main.rs
+++ b/examples/uart-demo/src/main.rs
@@ -7,13 +7,7 @@
 
 use base_address::Static;
 use bl_rom_rt::entry;
-use bl_soc::{
-    clocks::Clocks,
-    gpio::Pins,
-    prelude::*,
-    uart::{BitOrder, Config, Parity, StopBits, UartMuxes, WordLength},
-    UART,
-};
+use bl_soc::{clocks::Clocks, gpio::Pins, prelude::*, uart::UartMuxes, UART};
 use embedded_time::rate::*;
 use panic_halt as _;
 
@@ -38,12 +32,7 @@ fn main() -> ! {
     let sig2 = uart_muxes.sig2.into_transmit::<0>();
     let sig3 = uart_muxes.sig3.into_receive::<0>();
 
-    let config = Config {
-        bit_order: BitOrder::LsbFirst,
-        parity: Parity::None,
-        stop_bits: StopBits::One,
-        word_length: WordLength::Eight,
-    };
+    let config = Default::default();
     let mut serial = uart0.freerun(config, 2000000.Bd(), ((tx, sig2), (rx, sig3)), &clocks);
 
     let mut led = gpio.io8.into_floating_output();
diff --git a/src/glb_v1.rs b/src/glb/v1.rs
similarity index 100%
rename from src/glb_v1.rs
rename to src/glb/v1.rs
diff --git a/src/glb_v2.rs b/src/glb/v2.rs
similarity index 100%
rename from src/glb_v2.rs
rename to src/glb/v2.rs
diff --git a/src/lib.rs b/src/lib.rs
index f019a4882dc80b16da0d3904aefeb56a29e4d636..20a0a793f45fecc17c9c250f85b904796d5d7bb0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -14,9 +14,7 @@ use core::ops;
 pub mod clocks;
 /// Global configuration peripheral.
 pub mod glb {
-    #[path = "../glb_v1.rs"]
     pub mod v1;
-    #[path = "../glb_v2.rs"]
     pub mod v2;
 }
 
@@ -38,7 +36,6 @@ pub mod uart;
 
 /// Universal Serial Bus peripheral.
 pub mod usb {
-    #[path = "../usb_v1.rs"]
     pub mod v1;
 }
 
diff --git a/src/uart.rs b/src/uart.rs
index b79105cd0ddd84aa4f098f1b5ae0e0f5b525a4e6..1104052e402be6d698798ad397b6f64399c8ee27 100644
--- a/src/uart.rs
+++ b/src/uart.rs
@@ -1250,6 +1250,19 @@ pub struct Config {
     pub word_length: WordLength,
 }
 
+impl Default for Config {
+    /// Serial configuration defaults to 8-bit word, no parity check, 1 stop bit, LSB first.
+    #[inline]
+    fn default() -> Self {
+        Config {
+            bit_order: BitOrder::LsbFirst,
+            parity: Parity::None,
+            stop_bits: StopBits::One,
+            word_length: WordLength::Eight,
+        }
+    }
+}
+
 /// Order of the bits transmitted and received on the wire.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum BitOrder {
diff --git a/src/usb_v1.rs b/src/usb/v1.rs
similarity index 100%
rename from src/usb_v1.rs
rename to src/usb/v1.rs