diff --git a/include/zh_avr_i2c.h b/include/zh_avr_i2c.h
index bcec575..df55eb2 100644
--- a/include/zh_avr_i2c.h
+++ b/include/zh_avr_i2c.h
@@ -5,7 +5,6 @@
 #include "avr/io.h"
 #include "avr/interrupt.h"
 #include "stdbool.h"
-#include "stdio.h"
 
 #ifdef __cplusplus
 extern "C"
diff --git a/zh_avr_i2c.c b/zh_avr_i2c.c
index a305be7..d9c4786 100644
--- a/zh_avr_i2c.c
+++ b/zh_avr_i2c.c
@@ -20,8 +20,7 @@ typedef enum
 	MASTER_WRITE,
 	MASTER_READ,
 	MASTER_WRITE_REG,
-	MASTER_READ_REG,
-	MASTER_PROBE
+	MASTER_READ_REG
 } _work_mode_t;
 
 avr_err_t _zh_avr_i2c_master_start(TickType_t xTicksToWait);
@@ -52,12 +51,8 @@ avr_err_t zh_avr_i2c_master_init(const bool pullup)
 
 avr_err_t zh_avr_i2c_master_probe(const uint8_t addr, TickType_t xTicksToWait)
 {
-	// ZH_ERROR_CHECK(_master_is_initialized == true, AVR_ERR_INVALID_STATE);
-	// _work_mode = MASTER_PROBE;
-	// _target_i2c_address = addr;
-	// return _zh_avr_i2c_master_start(xTicksToWait);
 	uint8_t temp = 0;
-	return zh_avr_i2c_master_transmit(addr, &temp, 1, xTicksToWait);
+	return zh_avr_i2c_master_transmit(addr, &temp, sizeof(temp), xTicksToWait);
 }
 
 avr_err_t zh_avr_i2c_master_transmit(const uint8_t addr, uint8_t *data, uint8_t size, TickType_t xTicksToWait)
@@ -117,12 +112,10 @@ ISR(TWI_vect)
 	switch (TWSR & 0xF8)
 	{
 	case 0x00: // Bus error.
-		// printf("00\n");
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_BUS_FAIL, &xHigherPriorityTaskWoken);
 		break;
 	case 0x08: // A START condition has been transmitted.
-		// printf("08\n");
 		switch (_work_mode)
 		{
 		case MASTER_WRITE:
@@ -131,7 +124,6 @@ ISR(TWI_vect)
 			TWDR = (_target_i2c_address << 1) | I2C_MASTER_WRITE;
 			break;
 		case MASTER_READ:
-		case MASTER_PROBE:
 			TWDR = (_target_i2c_address << 1) | I2C_MASTER_READ;
 			break;
 		default:
@@ -140,22 +132,18 @@ ISR(TWI_vect)
 		TWCR = I2C_START;
 		break;
 	case 0x10: // A repeated START condition has been transmitted.
-		// printf("10\n");
-		// TWCR = I2C_START | (1 << TWSTO);
+		// To Do.
 		break;
 	case 0x18: // SLA+W has been transmitted. ACK has been received.
-		// printf("18\n");
 		TWDR = *(_master_data++);
 		--_master_data_size;
 		TWCR = I2C_START;
 		break;
 	case 0x20: // SLA+W has been transmitted. NACK has been received.
-		// printf("20\n");
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_NACK, &xHigherPriorityTaskWoken);
 		break;
 	case 0x28: // Data byte has been transmitted. ACK has been received.
-		// printf("28\n");
 		if (_master_data_size-- == 0)
 		{
 			TWCR = I2C_START | (1 << TWSTO);
@@ -168,17 +156,14 @@ ISR(TWI_vect)
 		}
 		break;
 	case 0x30: // Data byte has been transmitted. NACK has been received.
-		// printf("30\n");
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_NACK, &xHigherPriorityTaskWoken);
 		break;
 	case 0x38: // Arbitration lost in SLA+W or data bytes. Arbitration lost in SLA+R or NACK bit.
-		// printf("38\n");
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_COLLISION, &xHigherPriorityTaskWoken);
 		break;
 	case 0x40: // SLA+R has been transmitted. ACK has been received.
-		// printf("40\n");
 		switch (_work_mode)
 		{
 		case MASTER_WRITE:
@@ -197,22 +182,15 @@ ISR(TWI_vect)
 			break;
 		case MASTER_READ_REG:
 			break;
-		case MASTER_PROBE:
-			// TWCR = I2C_START | (1 << TWSTO);
-			TWCR = I2C_START;
-			xEventGroupSetBitsFromISR(_event_group_handle, I2C_OK, &xHigherPriorityTaskWoken);
-			break;
 		default:
 			break;
 		}
 		break;
 	case 0x48: // SLA+R has been transmitted. NACK has been received.
-		// printf("48\n");
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_NACK, &xHigherPriorityTaskWoken);
 		break;
 	case 0x50: // Data byte has been received. ACK has been returned.
-		// printf("50\n");
 		*(_master_data++) = TWDR;
 		if (--_master_data_size == 1)
 		{
@@ -224,7 +202,6 @@ ISR(TWI_vect)
 		}
 		break;
 	case 0x58: // Data byte has been received. NACK has been returned.
-		// printf("58\n");
 		*(_master_data) = TWDR;
 		TWCR = I2C_START | (1 << TWSTO);
 		xEventGroupSetBitsFromISR(_event_group_handle, I2C_OK, &xHigherPriorityTaskWoken);