// serial stuff
#include <stdio.h>
#include <stdlib.h>
#include "nrf24l01.h"


// PIN Setup
// SCK -> SCK2 (pin 26)
// SDI -> MISO (RPA4) (pin 12)
// SDO -> MOSI (RPB2) (pin 9)
// IRQ -> extern interrupt 1 (RPB10) (pin 21)
// CSN -> RPB9 (I/O) (pin 18)
// CE -> RPB8 (I/O) (pin 17)
// i/o names 

// frequency we're running at
#define	SYS_FREQ 64000000

char rf_spiwrite(unsigned char c){ // Transfer to SPI
    while (TxBufFullSPI2());
    WriteSPI2(c);
    while( !SPI2STATbits.SPIRBF); // check for complete transmit
    return ReadSPI2();
}

void init_SPI(){
    // Set up SPI2 to be active high, master, 8 bit mode, and ~4 Mhz CLK
    SpiChnOpen(2, SPI_OPEN_MSTEN | SPI_OPEN_MODE8 | SPI_OPEN_ON | SPI_OPEN_CKE_REV, 16);
    // Set SDI2 to pin 12
    PPSInput(3, SDI2, RPA4);
    // Set SDO2 to pin 9
    PPSOutput(3, RPA2, SDO2);
    // Set external interrupt 1 to pin 21
    PPSInput(4, INT1, RPB10);
    
    
    ConfigINT1(EXT_INT_PRI_2 | FALLING_EDGE_INT | EXT_INT_ENABLE);
    EnableINT1;
}

// Read a register from the nrf24l01
// reg is the array to read, len is the length of data expected to be received (1-5 bytes)
// NOTE: only address 0 and 1 registers use 5 bytes all others use 1 byte 
// NOTE: writing or reading payload is done using a specific command
void nrf_read_reg(char reg, char * buff, int len){
    //char reg_read[5]; // register used for reading a single register
    int i = 0;
    _csn = 0; // begin transmission
    status = rf_spiwrite(nrf24l01_R_REGISTER | reg); // send command to read register
    
    for(i=0;i<len;i++){
        buff[i] = rf_spiwrite(nrf24l01_SEND_CLOCK); // send clock pulse to continue receiving data
    }
    _csn = 1; // end transmission
}


void nrf_write_reg(char reg, char * data, char len){
    int i = 0;
    _csn = 0; // begin transmission
    status = rf_spiwrite(nrf24l01_W_REGISTER | reg); // send command to write reg
    for(i=0;i<len;i++){
        rf_spiwrite(data[i]); // write each char/byte to address reg
    }
    _csn = 1; // end transmission
}

// flushes the tx FIFO
void nrf_flush_tx(){
    _csn = 0;
    rf_spiwrite(nrf24l01_FLUSH_TX);
    _csn = 1;
    
}

// flushes the rx FIFO
// NOTE: do not use while sending acknowledge
void nrf_flush_rx(){
    _csn = 0;
    rf_spiwrite(nrf24l01_FLUSH_RX);
    _csn = 1;   
}


// Write a payload to be sent over the radio
// data: array of chars to be sent (1-32 chars/bytes)
// len: amount of chars in array/bytes to be sent
// NOT TESTED YET
void nrf_write_payload(char * data, char len){
    int i = 0;
    _csn = 0; // begin transmission
    status = rf_spiwrite(nrf24l01_W_TX_PAYLOAD); // send the command to write the payload
    for(i=0;i<len;i++){
        rf_spiwrite(data[i]); // write each char/byte to tx payload one at a time
    }
    _csn = 1; // end transmission
    
}

// should read the payload into a buffer NOT TESTED YET
void nrf_read_payload(char * buff){
    _csn = 0; // begin transmission
    status = rf_spiwrite(nrf24l01_R_RX_PAYLOAD); // send command to read payload
    int i;
    for(i=0;i<payload_size;i++){
        buff[i] = rf_spiwrite(nrf24l01_SEND_CLOCK);
    }
    _csn = 1; // end transmission

}

//Sets the power up bit and waits for the startup time, putting the radio in Standby-I mode
void nrf_pwrup(){
    nrf_read_reg(nrf24l01_CONFIG, &config, 1);
    config |= nrf24l01_CONFIG_PWR_UP;
    nrf_write_reg(nrf24l01_CONFIG, &config, 1);
    delay_ms(2);//Delay for power up time
}

//Clear the pwr_up bit, transitioning to power down mode
void nrf_pwrdown(){
    nrf_read_reg(nrf24l01_CONFIG, &config, 1);
    config &= ~(nrf24l01_CONFIG_PWR_UP);
    nrf_write_reg(nrf24l01_CONFIG, &config, 1);
    _ce = 0;
}

//Transitions to rx mode from standby mode
void nrf_rx_mode(){
//    nrf_read_reg(nrf24l01_STATUS, &status, 1); // read the status register
//    status |= nrf24l01_STATUS_RX_DR; // clear interrupt on radio
//    status |= nrf24l01_STATUS_TX_DS; // clear interrupt on radio
//    status |= nrf24l01_STATUS_MAX_RT; // clear interrupt on radio
//    nrf_write_reg(nrf24l01_STATUS, &status, 1);
    
    nrf_read_reg(nrf24l01_CONFIG, &config, 1);
    config |= nrf24l01_CONFIG_PRIM_RX;
    nrf_write_reg(nrf24l01_CONFIG, &config, 1);
    _ce = 1;
    delay_us(200); //Wait for transition to rx mode time

}

//Transitions to tx mode from standby mode
void nrf_tx_mode(){
//    nrf_read_reg(nrf24l01_STATUS, &status, 1); // read the status register
//    status |= nrf24l01_STATUS_RX_DR; // clear interrupt on radio
//    status |= nrf24l01_STATUS_TX_DS; // clear interrupt on radio
//    status |= nrf24l01_STATUS_MAX_RT; // clear interrupt on radio
//    nrf_write_reg(nrf24l01_STATUS, &status, 1);
    
    nrf_read_reg(nrf24l01_CONFIG, &config, 1);
    config &= ~(nrf24l01_CONFIG_PRIM_RX);
    nrf_write_reg(nrf24l01_CONFIG, &config, 1);
    _ce = 1;
    delay_us(200); //Wait for transition to tx mode time
    


}

void nrf_standby_mode(){
    _ce = 0;
}


// sets power of transmitter, possible values and definitions for them are
//  0dBm: nrf24l01_RF_SETUP_RF_PWR_0
// -6dBm: nrf24l01_RF_SETUP_RF_PWR_6
// -12dBm: nrf24l01_RF_SETUP_RF_PWR_12
// -18dBm: nrf24l01_RF_SETUP_RF_PWR_18
void nrf_set_transmit_pwr(char power){
    char setup;
    nrf_read_reg(nrf24l01_RF_SETUP, &setup, 1); // check value of setup register
    setup &= ~(nrf24l01_RF_SETUP_RF_PWR); // clear power bits in register
    setup |= power; // set power bits in register
    nrf_write_reg(nrf24l01_RF_SETUP, &setup, 1);  
}

// sets the rf data rate, possible values and definitoins for them are
// 250 kbps: nrf24l01_DR_LOW
// 1 Mbps: nrf24l01_DR_MED
// 2 Mbps: nrf24l01_DR_HIGH
void nrf_set_transmit_rate(char rate){
    char setup; // check value of setup register
    setup &= 0xd7;  // clear data rate bits in register
    setup |= rate; // set data rate bits in register
    nrf_write_reg(nrf24l01_RF_SETUP, &setup, 1); 
}

// Sends out a specified payload (in auto acknowledge mode by default)
// use after powering up radio, and setting address or other settings
void nrf_send_payload(char * data, int len){
    nrf_flush_tx(); // clear the TX FIFO so for a new transmission
    nrf_write_payload(data, len);
    nrf_tx_mode();
    while(!(sent)){ // wait until data sent interrupt triggers
        TRISBbits.TRISB3 = 0;
        LATBbits.LATB3 = 1;
    }
    LATBbits.LATB3 = 0;
    sent = 0;
    //_ce = 0; // transition to standby II mode
    
}

void __ISR(_EXTERNAL_1_VECTOR, ipl2) INT1Handler(void){
    //_LEDRED = 1;
    nrf_read_reg(nrf24l01_STATUS, &status, 1); // read the status register
    // check which type of interrupt occurred

    if (status & nrf24l01_STATUS_RX_DR) { // if data received
        nrf_read_payload(&RX_payload);
        received = 1; // signal main code that payload was received
        status |= nrf24l01_STATUS_RX_DR; // clear interrupt on radio
        nrf_flush_rx();
    }
        // if data sent or if acknowledge received when auto ack enabled
    else if (status & nrf24l01_STATUS_TX_DS) {
        //_LEDYELLOW = 1;
        sent = 1; // signal main code that payload was sent
        status |= nrf24l01_STATUS_TX_DS; // clear interrupt on radio
    } else { // maximum number of retransmit attempts occurred
        //_LEDRED = 1;
        error = 1; // signal main code that the payload was not received
        status |= nrf24l01_STATUS_MAX_RT; // clear interrupt on radio
    }
    
    nrf_write_reg(nrf24l01_STATUS, &status, 1);
    mINT1ClearIntFlag();
}