Update README.md

- add example code

README.md

@@ -18,18 +18,65 @@ __TAG - `ICM-20948` `AK09916` `SPI` `STM32 HAL`__
 - STM32CubeIDE
 - STM32 HAL driver
 - STM32F411CEU6
+- ICM-20948 module ( [SparkFun 9Dof IMU Breakout - ICM-20948 (Qwiic)](https://www.sparkfun.com/products/15335) )
 
-## ICM-20948 module
-[SparkFun 9Dof IMU Breakout - ICM-20948 (Qwiic)](https://www.sparkfun.com/products/15335)
-
-<img src = "https://user-images.githubusercontent.com/48342925/125441402-2af7d878-53d7-4d2f-83df-f304df4c330c.png" width = "40%"><img src = "https://user-images.githubusercontent.com/48342925/125441479-3370f3fb-8485-4d11-ad3e-1eb6e697f8e0.png" width = "40%">
+<img src = "https://user-images.githubusercontent.com/48342925/125441402-2af7d878-53d7-4d2f-83df-f304df4c330c.png" width = "25%">
+<img src = "https://user-images.githubusercontent.com/48342925/125441479-3370f3fb-8485-4d11-ad3e-1eb6e697f8e0.png" width = "25%">
 
 ## STM32CubeMX
 
-### SPI
+![image](https://user-images.githubusercontent.com/48342925/130714344-753f1b21-abe7-412c-b723-0826e43b9203.png)
 
+
+### SPI
 ![image](https://user-images.githubusercontent.com/48342925/129033034-ef4d8818-7338-4d90-bcd9-9d66491074bd.png)
 
 #### GPIO
-
 ![image](https://user-images.githubusercontent.com/48342925/129033151-7cf98ef2-22e9-44ef-8ddd-77b6ea9abf0b.png)
+
+
+## Example
+
+### icm20948.h
+- SPI1, PA4 (CS Pin)
+
+```c
+/* User Configuration */
+#define ICM20948_SPI					(&hspi1)
+
+#define ICM20948_SPI_CS_PIN_PORT		GPIOA
+#define ICM20948_SPI_CS_PIN_NUMBER		GPIO_PIN_4
+```
+
+### main.c
+- only contain relative things
+
+```c
+#include "icm20948.h"
+
+// variables to store sensor data
+axises my_gyro;
+axises my_accel;
+axises my_mag;
+
+int main(void)
+{
+    // initialize
+    // Modify the inside of init function for personal setting.
+    icm20948_init();
+    ak09916_init();
+
+    while (1)
+    {
+        // raw data
+        icm20948_gyro_read(&my_gyro);
+        icm20948_accel_read(&my_accel);
+        ak09916_mag_read(&my_mag);
+
+        // or unit conversion
+        icm20948_gyro_read_dps(&my_gyro);
+        icm20948_accel_read_g(&my_accel);
+        ak09916_mag_read_uT(&my_mag);
+    }
+}
+```