diff --git a/device/adc.c b/device/adc.c
index 0ba4ca6..1d02bca 100644
--- a/device/adc.c
+++ b/device/adc.c
@@ -64,11 +64,11 @@ static int mr_adc_close(struct mr_dev *dev)
     struct mr_adc_ops *ops = (struct mr_adc_ops *)dev->drv->ops;
 
     /* Disable all channels */
-    for (int i = 0; i < 32; i++)
+    for (size_t i = 0; i < 32; i++)
     {
         if (MR_BIT_IS_SET(adc->channel, (1 << i)) == MR_ENABLE)
         {
-            ops->channel_configure(adc, i, MR_DISABLE);
+            ops->channel_configure(adc, (int)i, MR_DISABLE);
             MR_BIT_CLR(adc->channel, (1 << i));
         }
     }
@@ -81,7 +81,7 @@ static ssize_t mr_adc_read(struct mr_dev *dev, int off, void *buf, size_t size,
     struct mr_adc *adc = (struct mr_adc *)dev;
     struct mr_adc_ops *ops = (struct mr_adc_ops *)dev->drv->ops;
     uint32_t *rd_buf = (uint32_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     /* Check if the channel is enabled */
     if (MR_BIT_IS_SET(adc->channel, (1 << off)) == MR_DISABLE)
diff --git a/device/dac.c b/device/dac.c
index 72f1d34..b536858 100644
--- a/device/dac.c
+++ b/device/dac.c
@@ -64,11 +64,11 @@ static int mr_dac_close(struct mr_dev *dev)
     struct mr_dac_ops *ops = (struct mr_dac_ops *)dev->drv->ops;
 
     /* Disable all channels */
-    for (int i = 0; i < 32; i++)
+    for (size_t i = 0; i < 32; i++)
     {
         if (MR_BIT_IS_SET(dac->channel, (1 << i)) == MR_ENABLE)
         {
-            ops->channel_configure(dac, i, MR_DISABLE);
+            ops->channel_configure(dac, (int)i, MR_DISABLE);
             MR_BIT_CLR(dac->channel, (1 << i));
         }
     }
@@ -81,7 +81,7 @@ static ssize_t mr_dac_write(struct mr_dev *dev, int off, const void *buf, size_t
     struct mr_dac *dac = (struct mr_dac *)dev;
     struct mr_dac_ops *ops = (struct mr_dac_ops *)dev->drv->ops;
     uint32_t *wr_buf = (uint32_t *)buf;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     /* Check if the channel is enabled */
     if (MR_BIT_IS_SET(dac->channel, (1 << off)) == MR_DISABLE)
diff --git a/device/i2c.c b/device/i2c.c
index 41f16dd..6e0295a 100644
--- a/device/i2c.c
+++ b/device/i2c.c
@@ -194,7 +194,7 @@ MR_INLINE ssize_t i2c_dev_read(struct mr_i2c_dev *i2c_dev, uint8_t *buf, size_t
     struct mr_i2c_bus *i2c_bus = (struct mr_i2c_bus *)i2c_dev->dev.parent;
     struct mr_i2c_bus_ops *ops = (struct mr_i2c_bus_ops *)i2c_bus->dev.drv->ops;
     uint8_t *rd_buf = (uint8_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     for (rd_size = 0; rd_size < size; rd_size += sizeof(*rd_buf))
     {
@@ -209,7 +209,7 @@ MR_INLINE ssize_t i2c_dev_write(struct mr_i2c_dev *i2c_dev, const uint8_t *buf,
     struct mr_i2c_bus *i2c_bus = (struct mr_i2c_bus *)i2c_dev->dev.parent;
     struct mr_i2c_bus_ops *ops = (struct mr_i2c_bus_ops *)i2c_bus->dev.drv->ops;
     uint8_t *wr_buf = (uint8_t *)buf;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     for (wr_size = 0; wr_size < size; wr_size += sizeof(*wr_buf))
     {
diff --git a/device/pin.c b/device/pin.c
index ee38e19..d1d4c60 100644
--- a/device/pin.c
+++ b/device/pin.c
@@ -96,7 +96,7 @@ static ssize_t mr_pin_read(struct mr_dev *dev, int off, void *buf, size_t size,
     struct mr_pin *pin = (struct mr_pin *)dev;
     struct mr_pin_ops *ops = (struct mr_pin_ops *)dev->drv->ops;
     uint8_t *rd_buf = (uint8_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     /* Check offset is valid */
     if (off < 0)
@@ -117,7 +117,7 @@ static ssize_t mr_pin_write(struct mr_dev *dev, int off, const void *buf, size_t
     struct mr_pin *pin = (struct mr_pin *)dev;
     struct mr_pin_ops *ops = (struct mr_pin_ops *)dev->drv->ops;
     uint8_t *wr_buf = (uint8_t *)buf;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     /* Check offset is valid */
     if (off < 0)
@@ -168,8 +168,7 @@ static ssize_t mr_pin_isr(struct mr_dev *dev, int event, void *args)
             ssize_t number = *(int *)args;
 
             /* If the irq exists, call it */
-            struct mr_list *list = MR_NULL;
-            for (list = pin->irq_list.next; list != &pin->irq_list; list = list->next)
+            for (struct mr_list *list = pin->irq_list.next; list != &pin->irq_list; list = list->next)
             {
                 struct pin_irq *irq = (struct pin_irq *)MR_CONTAINER_OF(list, struct pin_irq, list);
                 if (irq->number == number)
diff --git a/device/pwm.c b/device/pwm.c
index bbaba33..0957f88 100644
--- a/device/pwm.c
+++ b/device/pwm.c
@@ -100,8 +100,7 @@ static int pwm_calculate(struct mr_pwm *pwm, uint32_t freq)
     }
 
     /* Optimize the prescaler and period */
-    uint32_t divisor = 0;
-    for (divisor = 9; divisor > 1; divisor--)
+    for (uint32_t divisor = 9; divisor > 1; divisor--)
     {
         /* Check if reload value can be divided by current divisor */
         while ((psc_best % divisor) == 0)
@@ -152,11 +151,11 @@ static int mr_pwm_close(struct mr_dev *dev)
     struct mr_pwm_ops *ops = (struct mr_pwm_ops *)dev->drv->ops;
 
     /* Disable all channels */
-    for (int i = 0; i < 32; i++)
+    for (size_t i = 0; i < 32; i++)
     {
         if (MR_BIT_IS_SET(pwm->channel, (1 << i)) == MR_ENABLE)
         {
-            ops->channel_configure(pwm, i, MR_DISABLE, MR_PWM_POLARITY_NORMAL);
+            ops->channel_configure(pwm, (int)i, MR_DISABLE, MR_PWM_POLARITY_NORMAL);
             MR_BIT_CLR(pwm->channel, (1 << i));
         }
     }
@@ -169,7 +168,7 @@ static ssize_t mr_pwm_read(struct mr_dev *dev, int off, void *buf, size_t size,
     struct mr_pwm *pwm = (struct mr_pwm *)dev;
     struct mr_pwm_ops *ops = (struct mr_pwm_ops *)dev->drv->ops;
     uint32_t *rd_buf = (uint32_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     /* Check if the channel is enabled */
     if (MR_BIT_IS_SET(pwm->channel, (1 << off)) == MR_DISABLE)
@@ -191,7 +190,7 @@ static ssize_t mr_pwm_write(struct mr_dev *dev, int off, const void *buf, size_t
     struct mr_pwm *pwm = (struct mr_pwm *)dev;
     struct mr_pwm_ops *ops = (struct mr_pwm_ops *)dev->drv->ops;
     uint32_t *wr_buf = (uint32_t *)buf;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     /* Check if the channel is enabled */
     if (MR_BIT_IS_SET(pwm->channel, (1 << off)) == MR_DISABLE)
diff --git a/device/serial.c b/device/serial.c
index 988c60f..a4df74f 100644
--- a/device/serial.c
+++ b/device/serial.c
@@ -46,7 +46,7 @@ static ssize_t mr_serial_read(struct mr_dev *dev, int off, void *buf, size_t siz
     struct mr_serial *serial = (struct mr_serial *)dev;
     struct mr_serial_ops *ops = (struct mr_serial_ops *)dev->drv->ops;
     uint8_t *rd_buf = (uint8_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     if (mr_ringbuf_get_bufsz(&serial->rd_fifo) == 0)
     {
@@ -67,7 +67,7 @@ static ssize_t mr_serial_write(struct mr_dev *dev, int off, const void *buf, siz
     struct mr_serial *serial = (struct mr_serial *)dev;
     struct mr_serial_ops *ops = (struct mr_serial_ops *)dev->drv->ops;
     uint8_t *wr_buf = (uint8_t *)buf;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     if ((async == MR_SYNC) || (mr_ringbuf_get_bufsz(&serial->wr_fifo) == 0))
     {
@@ -231,7 +231,7 @@ static ssize_t mr_serial_isr(struct mr_dev *dev, int event, void *args)
         case MR_ISR_SERIAL_WR_INT:
         {
             /* Write data from FIFO, if FIFO is empty, stop transmit */
-            uint8_t data = 0;
+            uint8_t data;
             if (mr_ringbuf_pop(&serial->wr_fifo, &data) == sizeof(data))
             {
                 ops->write(serial, data);
diff --git a/device/soft_i2c.c b/device/soft_i2c.c
index c37c688..5501795 100644
--- a/device/soft_i2c.c
+++ b/device/soft_i2c.c
@@ -33,7 +33,7 @@ MR_INLINE void soft_i2c_bus_sda_set(struct mr_soft_i2c_bus *soft_i2c_bus, uint8_
 
 MR_INLINE uint8_t soft_i2c_sda_get(struct mr_soft_i2c_bus *soft_i2c_bus)
 {
-    uint8_t value = 0;
+    uint8_t value;
 
     mr_dev_ioctl(soft_i2c_bus->desc, MR_CTL_PIN_SET_NUMBER, &soft_i2c_bus->sda_pin);
     mr_dev_read(soft_i2c_bus->desc, &value, sizeof(value));
diff --git a/device/spi.c b/device/spi.c
index b143c59..c0088fb 100644
--- a/device/spi.c
+++ b/device/spi.c
@@ -263,7 +263,7 @@ static ssize_t spi_dev_transfer(struct mr_spi_dev *spi_dev, void *rd_buf, const
 {
     struct mr_spi_bus *spi_bus = (struct mr_spi_bus *)spi_dev->dev.parent;
     struct mr_spi_bus_ops *ops = (struct mr_spi_bus_ops *)spi_bus->dev.drv->ops;
-    size_t tf_size = 0;
+    size_t tf_size;
 
     if (rdwr == MR_SPI_RD)
     {
diff --git a/device/timer.c b/device/timer.c
index e8e02de..d0c90e2 100644
--- a/device/timer.c
+++ b/device/timer.c
@@ -14,7 +14,7 @@ static int timer_calculate(struct mr_timer *timer, uint32_t timeout)
 {
     uint32_t clk = timer->info->clk, psc_max = timer->info->prescaler_max, per_max = timer->info->period_max;
     uint32_t psc_best = 0, per_best = 0, reload_best = 0;
-    uint32_t psc = 0;
+    uint32_t psc;
     int error_min = INT32_MAX;
 
     /* Check the clock */
@@ -127,7 +127,7 @@ static ssize_t mr_timer_read(struct mr_dev *dev, int off, void *buf, size_t size
     struct mr_timer *timer = (struct mr_timer *)dev;
     struct mr_timer_ops *ops = (struct mr_timer_ops *)dev->drv->ops;
     uint32_t *rd_buf = (uint32_t *)buf;
-    ssize_t rd_size = 0;
+    ssize_t rd_size;
 
     MR_BIT_CLR(size, sizeof(*rd_buf) - 1);
     for (rd_size = 0; rd_size < size; rd_size += sizeof(*rd_buf))
@@ -148,7 +148,7 @@ static ssize_t mr_timer_write(struct mr_dev *dev, int off, const void *buf, size
     struct mr_timer_ops *ops = (struct mr_timer_ops *)dev->drv->ops;
     uint32_t *wr_buf = (uint32_t *)buf;
     uint32_t timeout = 0;
-    ssize_t wr_size = 0;
+    ssize_t wr_size;
 
     /* Only the last write is valid */
     MR_BIT_CLR(size, sizeof(*wr_buf) - 1);
diff --git a/document/device/serial/serial.md b/document/device/serial/serial.md
index 37cbdca..fd9daf4 100644
--- a/document/device/serial/serial.md
+++ b/document/device/serial/serial.md
@@ -89,7 +89,7 @@ SERIAL设备配置：
 - `stop_bits`：停止位数。
 - `parity`：校验位。
 - `bit_order`：数据传输顺序。
-- `invert`：极性反转。
+- `polarity`：极性反转。
 
 ```c
 /* 设置默认配置 */
diff --git a/document/device/serial/serial_EN.md b/document/device/serial/serial_EN.md
index d0af964..e7f5bb4 100644
--- a/document/device/serial/serial_EN.md
+++ b/document/device/serial/serial_EN.md
@@ -91,7 +91,7 @@ SERIAL device configuration:
 - `stop_bits`: Stop bits
 - `parity`: Parity check
 - `bit_order`: Data transmission order
-- `invert`: Polarity inversion
+- `polarity`: Polarity inversion
 
 ```c
 /* Set default configuration */
diff --git a/include/mr_def.h b/include/mr_def.h
index 7e541f7..9adb32f 100644
--- a/include/mr_def.h
+++ b/include/mr_def.h
@@ -66,7 +66,7 @@ typedef int (*mr_init_fn_t)(void);
  * @brief Exports an auto initialization function with level.
  */
 #define MR_INIT_EXPORT(fn, level) \
-    MR_USED const mr_init_fn_t _mr_auto_init_##fn MR_SECTION(".auto_init."level) = fn
+    MR_USED const mr_init_fn_t _mr_auto_init_##fn MR_SECTION(".mr_auto_init."level) = fn
 
 /**
  * @brief Exports a board auto initialization function.
diff --git a/include/mr_service.h b/include/mr_service.h
index c1cc386..e40a4b8 100644
--- a/include/mr_service.h
+++ b/include/mr_service.h
@@ -103,7 +103,7 @@ extern "C" {
  *
  * @return The number of elements in the array.
  */
-#define MR_ARRAY_SIZE(array)             (sizeof(array)/sizeof((array)[0]))
+#define MR_ARRAY_NUM(array)             (sizeof(array)/sizeof((array)[0]))
 
 /**
  * @brief This macro function gets the maximum of two values.
diff --git a/source/device.c b/source/device.c
index ad6147b..7069958 100644
--- a/source/device.c
+++ b/source/device.c
@@ -74,13 +74,12 @@ MR_INLINE const char *dev_clear_path(const char *path)
 MR_INLINE int dev_register_by_path(struct mr_dev *parent, struct mr_dev *dev, const char *path)
 {
     char child_name[MR_CFG_NAME_MAX + 1] = {0};
-    const char *child_path = MR_NULL;
 
     /* Clear the path */
     path = dev_clear_path(path);
 
     /* Check whether the child path exists */
-    child_path = strchr(path, '/');
+    const char *child_path = strchr(path, '/');
     if (child_path != MR_NULL)
     {
         /* Get the child name */
@@ -107,13 +106,12 @@ MR_INLINE int dev_register_by_path(struct mr_dev *parent, struct mr_dev *dev, co
 MR_INLINE struct mr_dev *dev_find_by_path(struct mr_dev *parent, const char *path)
 {
     char child_name[MR_CFG_NAME_MAX + 1] = {0};
-    const char *child_path = MR_NULL;
 
     /* Clear the path */
     path = dev_clear_path(path);
 
     /* Check whether the child path exists */
-    child_path = strchr(path, '/');
+    const char *child_path = strchr(path, '/');
     if (child_path != MR_NULL)
     {
         /* Get the child name */
@@ -421,7 +419,7 @@ int mr_dev_register(struct mr_dev *dev,
                     struct mr_dev_ops *ops,
                     struct mr_drv *drv)
 {
-    static struct mr_dev_ops null_ops = {0};
+    static struct mr_dev_ops null_ops = {MR_NULL};
 
     MR_ASSERT(dev != MR_NULL);
     MR_ASSERT(dev->magic != MR_MAGIC_NUMBER);