/* 
 * PORTG0 and PORTG1 can    N E V E R    both be set high at the same time. This will cause
 * a short circuit between +12V and -12V, which will most likely fry a regulator, as well as the
 * Microcontroller, and may damage the CUSat space vehicle or any component inside it.
 */

#include <mega128.h>

//some macros
#define BT_CHRG            PORTC.4 = 0
#define BT_DISCHRG         PORTC.4 = 1  
#define USRAT0_REC_EN      PORTC.5 = 0   //enable  RS485 receive
#define USART0_SEND_EN     PORTC.6 = 1   //enable  RS485 send
#define USART0_SEND_DS     PORTC.6 = 0   //disable RS485 send 
#define TXB8N_SET          UCSR0B.0 = 1  //set 9th bit  
#define TXB8N_CLR          UCSR0B.0 = 0  //clear the 9th bit

//status and external command definitions
#define DB_WAIT                0x00     //initial status
#define DB_CMD_REPROG_MCU      0x01     //reprogram subsystems
#define DB_CMD_GET_ALL_DATA    0x02     //PC request ADC data from DB
#define DB_CMD_GET_CUCP        0x03     //PC request data from MCU
#define DB_CMD_BAT_DISCHRG     0x04     //start charge circuit
#define DB_CMD_BAT_CHARGE      0x05     //stop charge circuit     
#define DB_CMD_BAT_OFF         0x06
#define DB_CMD_INHIBIT_POS     0x07
#define DB_CMD_INHIBIT_NEG     0x08
#define DB_CMD_INHIBIT_OFF     0x09
#define REPROG_MCU_GET_ADDR    0x10     //get MCU reprogramming address 
#define REPROG_MCU_GET_CMD     0x11     //get MCU reprogramming command 
#define REPROG_MCU_END         0x14     // end of reprogramming

//db_cmd definition
#define NO_ACTION              0x00     //initial status
#define SEND_ADC_DATA          0x01     //send adc data to pc
#define SEND_MCU_DATA          0x02     //send MCU data to pc
#define BAT_CHRG               0x03     //battery charge
#define BAT_DISCHRG            0x04     //battery discharge   
#define BAT_OFF                0x05                      
#define INHIBIT_POS            0x06
#define INHIBIT_NEG            0x07
#define INHIBIT_OFF            0x08

//ADC register
#define ADEN  ADCSRA.7           //enable ADC
#define ADSC  ADCSRA.6           //start conversion
#define ADIF  ADCSRA.4           //conversion done

//timeout values for each task
#define t1 50                    // data acquisition every 50 ms   

// ADC data
struct ALL_MCU_DATA {
    char CHARGE_CURRENT_SENSE;
    char DISCHARGE_CURRENT_SENSE;
    char VBUS_CURRENT_SENSE;
    char inhibitState;
    char batteryState;
} allMCUData;

//variable definition
unsigned char status;                // diagnostic board status     
unsigned char rp_in_prog;            // reprogramming in progress
unsigned char db_cmd;                // command for DB
unsigned char time1;	             // timeout counters
unsigned char cucp_buffer[256];      // data from MCU
unsigned int cucp_buffer_index=0;

//functions definition
void get_adc_data(void); 
void send_adc_data(void);
void send_mcu_data(void);
void bat_charge(void);
void bat_discharge(void);
void bat_off(void);
void inhibit_pos(void);
void inhibit_neg(void);
void inhibit_off(void);
void initialize(void);

// timer 0 interrupt
interrupt [TIM0_COMP] void timer0_compare(void) {
  if (time1>0)	--time1;
}

void get_adc_data() {   // data acquisition every 50 ms
    time1=t1;
    ADSC = 1;            //start conversion
    while(!ADIF);        //wait until conversion done
    allMCUData.DISCHARGE_CURRENT_SENSE = ADCH;
}

void send_adc_data() {
    char ct=0;
    while(ct<sizeof(struct ALL_MCU_DATA))
    {
        while(!(UCSR1A & 0x20));    //USART1
        UDR1 = *((char*)allMCUData+ct);
        ct++;
    }

}

void send_mcu_data(void){
    unsigned char i;
    UDR1 = cucp_buffer_index;
    for(i=0; i<cucp_buffer_index;i++)
    {
        while(!(UCSR1A & 0x20));
        UDR1 = cucp_buffer[i];
    }
    cucp_buffer_index = 0;
}

inline void bat_charge(void){
    allMCUData.batteryState = 7;
}

inline void bat_discharge(void){
    PORTC.2 = 1;
    allMCUData.batteryState = 8;
}

inline void bat_off(void){
    PORTC.2 = 0;
    allMCUData.batteryState = 9;
}

inline void inhibit_pos(void){
    allMCUData.inhibitState = 10;
}

inline void inhibit_neg(void){
    allMCUData.inhibitState = 11;
}

inline void inhibit_off(void){
    allMCUData.inhibitState = 12;
}

void initialize(void) {
    UBRR0L = 103;  //9600 bps   to MCU
    UBRR1L = 103;  //9600 bps   to PC
    UCSR0B = 0b10011100; //enable USART0 receiver, 9 bits ,0b10011100
    UCSR1B = 0b10011000; //enable USART1 transmitter and receriver

	//set up timer 0
    TIMSK=2;        //turn on timer 0 cmp match ISR
    OCR0 = 250;     //set the compare re to 250 time ticks
	                //prescalar to 64 and turn on clear-on-match

    TCCR0=0b00001011;

    ADMUX = 0b00100101;    //channel 5 selected
    ADCSRA = 0b11000111; //ADC enabled, start conversion, prescaler-128

    DDRC = 0xff;
    DDRG = 0x03;

    USRAT0_REC_EN;

    time1 = t1;

    status = DB_WAIT;
    db_cmd = NO_ACTION;

    #asm ("sei");
}                          

interrupt [USART0_RXC] void uart0_rec(void){      // from MCU
    unsigned char r_char;
    r_char = UDR0;
    if(rp_in_prog) {
        UDR1 = r_char;                        // forward data to PC
        if(r_char == REPROG_MCU_END) {
            	  rp_in_prog =0;
            	  USART0_SEND_DS;                   //disable RS485 transmitter
            	  UCSR0B = 0b10011100;              //back to 9 bits
            	  status = DB_WAIT;                 //back to initial state
        }
    } else {
        cucp_buffer[cucp_buffer_index++] = r_char;
    }
}

interrupt [USART1_RXC] void uart1_rec(void){      // to PC
    unsigned char r_char;
    r_char = UDR1;
    switch(status) {
        case DB_WAIT:
            UDR1 = r_char; // echo back to PC so it knows we got the data
            switch (r_char) {
                case DB_CMD_REPROG_MCU:
                    status = REPROG_MCU_GET_ADDR;
                    break;
                case DB_CMD_GET_ALL_DATA:
                    db_cmd = SEND_ADC_DATA;  // send all current ADC data here
                    break;
                case DB_CMD_GET_CUCP:
                    db_cmd = SEND_MCU_DATA;  // send chunk of CUCP data here
                    break;
                case DB_CMD_BAT_CHARGE:
                    db_cmd = BAT_CHRG;       // start charge circuit
                    break;
                case DB_CMD_BAT_DISCHRG:
                    db_cmd = BAT_DISCHRG;    // stop charge circuit
                    break;
                case DB_CMD_BAT_OFF:
                    db_cmd = BAT_OFF;
		            break;
                case DB_CMD_INHIBIT_POS:
                    db_cmd = INHIBIT_POS;
                    break;
                case DB_CMD_INHIBIT_NEG:
                    db_cmd = INHIBIT_NEG;
                    break;
                case DB_CMD_INHIBIT_OFF:
                    db_cmd = INHIBIT_OFF;
		            break;
            }
            break;

        case REPROG_MCU_GET_ADDR:         //get target address
            rp_in_prog =1;
            USART0_SEND_EN;               //enable    PORTC.6 =1
            TXB8N_SET;                    //TXB8n = 1
            UDR0 = r_char;                //relay this addr to MCU
            status =  REPROG_MCU_GET_CMD;
            break;

        case REPROG_MCU_GET_CMD:
            UCSR0B = 0b10011000;
            UDR0 = r_char;
            break;
    }
}

void main(void) {
    initialize();

    while(1) {
        if (time1==0)	get_adc_data();    //data acquisition every 100 ms
        switch(db_cmd) {
            case SEND_ADC_DATA:
                send_adc_data();
                break;
            case SEND_MCU_DATA:
               send_mcu_data();
               break;
            case BAT_CHRG:
               bat_charge();
               break;
            case BAT_DISCHRG:
                bat_discharge();
                break;
            case BAT_OFF:
                bat_off();
                break;
           	case INHIBIT_POS:
                inhibit_pos();
                break;
            case INHIBIT_NEG:
                inhibit_neg();
                break;
            case INHIBIT_OFF:
                inhibit_off();
                break;
       }
       db_cmd = NO_ACTION;
   }
}