Implement I2C communication with RPi

Core/Inc/rpi.h

@@ -3,6 +3,8 @@
 
 #include "stm32g4xx_hal.h"
 
+#include <stddef.h>
+
 // We only need to receive one byte (command ID)
 #define I2C_RX_BUF_SIZE 1
 extern uint8_t i2c_rx_buf[I2C_RX_BUF_SIZE];
@@ -21,6 +23,10 @@ typedef enum {
 } RPiI2CState;
 extern RPiI2CState rpi_i2c_state;
 
+extern size_t rpi_num_polls;
+
 void rpi_init(I2C_HandleTypeDef *handle);
 
+void rpi_update_tx_buffer();
+
 #endif // __RPI_H

Core/Inc/state.h

@@ -0,0 +1,19 @@
+#ifndef __STATE_H
+#define __STATE_H
+
+typedef enum {
+  VIEW_MISSION_SELECT = 0,
+  VIEW_AMI = 1,
+  VIEW_DRIVER = 2,
+  VIEW_TESTING = 3
+} STWView;
+
+typedef struct {
+  STWView view;
+} STWState;
+
+extern STWState stw_state;
+
+void state_init();
+
+#endif // __STATE_H