diff --git a/include/si5351_driver.h b/include/si5351_driver.h
new file mode 100644
index 0000000..66220cb
--- /dev/null
+++ b/include/si5351_driver.h
@@ -0,0 +1,70 @@
+/*
+ * si5351_driver.h
+ *
+ *  Created on: 16. aug. 2024
+ *      Author: Christian L. V. Madsen (OZ1CM)
+ */
+
+#ifndef SI5351_DRIVER_INCLUDE_SI5351_DRIVER_H_
+#define SI5351_DRIVER_INCLUDE_SI5351_DRIVER_H_
+
+#include "stdio.h"
+#include "stdint.h"
+
+typedef int (*setGet_I2C_Event_fpt)(void *inst, uint8_t *data, uint32_t len, uint8_t set_get);
+
+typedef struct{
+
+	uint8_t SYS_INIT : 1; // System Initialization Status
+	uint8_t LOL_A : 1; // PLLB Loss Of Lock Status.
+	uint8_t LOL_B : 1; // PLL A Loss Of Lock Status.
+	uint8_t LOS_CLKIN : 1; // CLKIN Loss Of Signal (Si5351C Only).
+	uint8_t LOS_XTAL : 1; // Crystal Loss of Signal
+	uint8_t RESERVED : 1;
+	uint8_t REVID : 2; //  Revision number of the device.
+
+
+}__attribute__((packed)) si5351_deviceStat;
+
+typedef struct{
+
+	uint8_t SYS_INIT_STKY : 1; // System Calibration Status Sticky Bit
+	uint8_t LOL_A_STKY : 1; // PLLB Loss Of Lock Status Sticky Bit
+	uint8_t LOL_B_STKY : 1; // PLL A Loss Of Lock Status Sticky Bit.
+	uint8_t LOS_CLKIN_STKY : 1; // CLKIN Loss Of Signal (Si5351C Only) Sticky Bit.
+	uint8_t LOS_XTAL_STKY : 1; // Crystal Loss of Signal Sticky Bit.
+	uint8_t RESERVED : 3;
+
+
+}__attribute__((packed)) si5351_interruptStatusSticky;
+
+typedef struct{
+
+
+
+
+}__attribute__((packed)) si5351_outputEnableControl;
+
+typedef struct{
+
+	si5351_deviceStat deviceStatus;
+	si5351_interruptStatusSticky ISR_StatusSticky;
+
+
+}__attribute__((packed)) si5351_data;
+
+typedef struct{
+
+	void *i2c_transfer_inst;
+	setGet_I2C_Event_fpt i2c_transfer_evt;
+
+	si5351_data device_data;
+
+
+}__attribute__((packed)) si5351_driver;
+
+int cm_si5351_init(si5351_driver *inst, void *i2c_transfer_inst, setGet_I2C_Event_fpt i2c_transfer_evt);
+uint8_t cm_si5351_getRevisionNumber(si5351_driver *inst);
+
+
+#endif /* SI5351_DRIVER_INCLUDE_SI5351_DRIVER_H_ */
diff --git a/si5351_driver.c b/si5351_driver.c
new file mode 100644
index 0000000..b122b47
--- /dev/null
+++ b/si5351_driver.c
@@ -0,0 +1,45 @@
+/*
+ * si5351_driver.c
+ *
+ *  Created on: 16. aug. 2024
+ *      Author: Christian L. V. Madsen (OZ1CM)
+ */
+#include "include/si5351_driver.h"
+
+enum{
+	SI5351_I2C_GET = 0,
+	SI5351_I2C_SET = 1,
+
+};
+
+uint8_t cm_si5351_getRevisionNumber(si5351_driver *inst){
+
+	// Read Device Status register:
+	inst->i2c_transfer_evt(inst->i2c_transfer_inst,(uint8_t*) &(inst->device_data.deviceStatus),sizeof(inst->device_data.deviceStatus), SI5351_I2C_GET);
+
+
+	return inst->device_data.deviceStatus.REVID;
+}
+
+int cm_si5351_init(si5351_driver *inst, void *i2c_transfer_inst, setGet_I2C_Event_fpt i2c_transfer_evt){
+
+	if(inst == NULL)return -1;
+	if(i2c_transfer_inst == NULL)return -1;
+	if(i2c_transfer_evt == NULL)return -1;
+
+	inst->i2c_transfer_inst = i2c_transfer_inst;
+	inst->i2c_transfer_evt = i2c_transfer_evt;
+
+	int ret = 0;
+
+	// SW Reset device.
+	//ret = cm_ltr390_SWreset(inst);
+
+//	ret = ltr390_readAllReg(inst);
+
+	return ret;
+
+
+
+}
+