HAL.h

// Hardware Abstraction Layer
// See https://www.st.com/resource/en/user_manual/um1725-description-of-stm32f4-hal-and-lowlayer-drivers-stmicroelectronics.pdf
// for description of HAL interface used on STM32 microcontrollers, which serves as an example architecture

#ifndef HAL_H
#define	HAL_H

#ifndef NULL
#define NULL ((void*)0)
#endif

#if defined(__DEBUG) && __DEBUG
// In order to force a branch or loop to be compiled as-is in debug mode, increment
// this variable from somewhere in the branch or loop, and it will be forced to be
// compiled into the code. This variable should not be used for release builds because
// it serves no purpose and is not truly volatile, so doing so is a compile error.
extern volatile int SIDE_EFFECT_FOR_DEBUGGING;
#endif

//#include "xc.h"
#include <stdint.h> // for uint32_t

extern void* const PORT_A;
extern void* const PORT_B;

// sets up the pins chosen by the bit mask from the selected port as general purpose outputs
//void HAL_GPIO_Init(void* port, uint32_t pins);
// toggles any output pins chosen by the bit mask from the selected port
//void HAL_GPIO_TogglePin(void* port, uint32_t pins);

// sets up GCLK2 and TC0 to run at 32kHz
void HAL_32kHz_Init();
// turns off CPU and peripherals; keeps RAM, stack, and GP registers. interrupts and
// returns using TC0 after the time expires - requires 32kHz to be initialized
void HAL_Sleep(uint32_t millis);
// gives the elapsed time according to the ultra low-power 32kHz clock, in ticks
// overflows each 1.5 days: this function is appropriate only for measuring small
// elapsed durations and requires 32kHz to be initialized
uint32_t HAL_getTime();

enum HAL_Device {
    adcs = 0x0c,
    prop = 0x0d,
    eps = 0x0b // as specified in EPS ICD
};

// CDH -> external device
void HAL_I2C_sendData(
    enum HAL_Device device,  // device number
    uint8_t data[],        // array of data to be sent
    int dataSize        // the size of data[]
);

// external device -> CDH
void HAL_I2C_registerDataRecievedCallback(
    enum HAL_Device device,  // device must send its address in I2C transmission
    void (*dataRecieved)(char data[], int dataSize) // data received callback
);

#endif	/* HAL_H */