GNSS

/*                             GNSS (source code)                             */  
/*                            MCU: PIC24FJ256GA702                            */
/*                              Author: Michael                               */

/**************************** Configuration Bits ******************************/

// FSEC
#pragma config BWRP = OFF                                                       // Boot Segment Write-Protect bit (Boot Segment may be written)
#pragma config BSS = DISABLED                                                   // Boot Segment Code-Protect Level bits (No Protection (other than BWRP))
#pragma config BSEN = OFF                                                       // Boot Segment Control bit (No Boot Segment)
#pragma config GWRP = OFF                                                       // General Segment Write-Protect bit (General Segment may be written)
#pragma config GSS = DISABLED                                                   // General Segment Code-Protect Level bits (No Protection (other than GWRP))
#pragma config CWRP = OFF                                                       // Configuration Segment Write-Protect bit (Configuration Segment may be written)
#pragma config CSS = DISABLED                                                   // Configuration Segment Code-Protect Level bits (No Protection (other than CWRP))
#pragma config AIVTDIS = OFF                                                    // Alternate Interrupt Vector Table bit (Disabled AIVT)

// FBSLIM
#pragma config BSLIM = 0x1FFF                                                   // Boot Segment Flash Page Address Limit bits (Enter Hexadecimal value)

// FOSCSEL
#pragma config FNOSC = PRIPLL                                                   // Oscillator Source Selection (Primary Oscillator with PLL module (XT + PLL, HS + PLL, EC + PLL))
#pragma config PLLMODE = PLL96DIV4                                              // PLL Mode Selection (96 MHz PLL. Oscillator input is divided by 4 (16 MHz input))
#pragma config IESO = OFF                                                       // Two-speed Oscillator Start-up Enable bit (Start up with user-selected oscillator source)

// FOSC
#pragma config POSCMD = HS                                                      // Primary Oscillator Mode Select bits (HS Crystal Oscillator Mode)
#pragma config OSCIOFCN = ON                                                    // OSC2 Pin Function bit (OSC2 is general purpose digital I/O pin)
#pragma config SOSCSEL = OFF                                                    // SOSC Power Selection Configuration bits (Digital (SCLKI) mode)
#pragma config PLLSS = PLL_PRI                                                  // PLL Secondary Selection Configuration bit (PLL is fed by the Primary oscillator)
#pragma config IOL1WAY = OFF                                                    // Peripheral pin select configuration bit (Allow multiple reconfigurations)
#pragma config FCKSM = CSDCMD                                                   // Clock Switching Mode bits (Both Clock switching and Fail-safe Clock Monitor are disabled)

// FWDT
#pragma config WDTPS = PS1                                                      // Watchdog Timer Postscaler bits (1:1)
#pragma config FWPSA = PR32                                                     // Watchdog Timer Prescaler bit (1:32)
#pragma config FWDTEN = OFF                                                     // Watchdog Timer Enable bits (WDT and SWDTEN disabled)
#pragma config WINDIS = OFF                                                     // Watchdog Timer Window Enable bit (Watchdog Timer in Non-Window mode)
#pragma config WDTWIN = WIN50                                                   // Watchdog Timer Window Select bits (WDT Window is 50% of WDT period)
#pragma config WDTCMX = WDTCLK                                                  // WDT MUX Source Select bits (WDT clock source is determined by the WDTCLK Configuration bits)
#pragma config WDTCLK = SYSCLK                                                  // WDT Clock Source Select bits (WDT uses system clock when active, LPRC while in Sleep mode)

// FPOR
#pragma config BOREN = OFF                                                      // Brown Out Enable bit (Brown Out Disabled)
#pragma config LPCFG = OFF                                                      // Low power regulator control (No Retention Sleep)
#pragma config DNVPEN = DISABLE                                                 // Downside Voltage Protection Enable bit (Downside protection disabled when BOR is inactive)

// FICD
#pragma config ICS = PGD1                                                       // ICD Communication Channel Select bits (Communicate on PGEC1 and PGED1)
#pragma config JTAGEN = OFF                                                     // JTAG Enable bit (JTAG is disabled)

// FDEVOPT1
#pragma config ALTCMPI = DISABLE                                                // Alternate Comparator Input Enable bit (C1INC, C2INC, and C3INC are on their standard pin locations)
#pragma config TMPRPIN = OFF                                                    // Tamper Pin Enable bit (TMPRN pin function is disabled)
#pragma config SOSCHP = ON                                                      // SOSC High Power Enable bit (valid only when SOSCSEL = 1 (Enable SOSC high power mode (default))
#pragma config ALTI2C1 = ALTI2CEN                                               // Alternate I2C pin Location (SDA1 and SCL1 on RB9 and RB8)

/************************* Configuration Bits (end) ***************************/

#define FCY 16000000                                                            // FCY = FOSC / 2 (FCY: Instruction clock cycle) (FOSC: System clock cycle)

#include <libpic30.h>                                                           // Delay functions
#include <xc.h>                                                                 // MCU pin mapping
#include "L86-M33.h"                                                            // GNSS Receiver: Quectel L86-M33

int main(void)                           
{

    // Set pin direction
    TRISBbits.TRISB8 = 1;                                                       // Set MCU Pin #17 to input (I2C1 SCL1)
    TRISBbits.TRISB9 = 1;                                                       // Set MCU Pin #18 to input (I2C1 SDA1)
    TRISBbits.TRISB6 = 1;                                                       // Set MCU Pin #15 to input (UART1 RX)
    TRISBbits.TRISB7 = 0;                                                       // Set MCU Pin #16 to output (UART1 TX)    
    
    /************************ configure MCU modules *************************/

    // Analog Ports
    ANSA = 0;                                                                   // Disable A (PIC24FJ256GA702 datasheet p.126 Table 11-1)
    ANSB = 0;
    
    // Comparators
    CM1CONbits.CEN = 0;                                                         // Disable #1 (PIC24FJ256GA702 datasheet p.310 Register 25-1)
    CM2CONbits.CEN = 0;                                                         
    CM3CONbits.CEN = 0;                                                         
  
    // ADC
    AD1CON1bits.ADON = 0;                                                       // Disable module (PIC24FJ256GA702 datasheet p.291 Register 24-1) 

    // UART1
    RPINR18bits.U1RXR = 6;                                                      // Assign UART1 RX to RP6 (MCU Pin #15) (PIC24FJ256GA702 datasheet p.146 Register 11-23)
    RPOR3bits.RP7R = 3;                                                         // Assign UART1 TX to RP7 (MCU Pin #16) (PIC24FJ256GA702 datasheet p.152 Register 11-35)
    U1BRG = 103;                                                                // Baud rate (9600bps)(PIC24FJ256GA702 datasheet p.229 Eqn.19-1)
    U1MODEbits.UARTEN = 1;                                                      // Enable module (PIC24FJ256GA702 datasheet p.231 Register 19-1)
    U1STAbits.URXEN = 1;                                                        // Enable RX (PIC24FJ256GA702 datasheet p.233 Register 19-2)
    U1STAbits.UTXEN = 1;                                                        // Enable TX

    /********************* configure MCU modules (end) **********************/   

    PMTK_CMD_FULL_COLD_START();                                                 // Set operating conditions for L86-M33 (factory settings)
    
    while(1)
    {      
                                                                                // Empty loop
    }
    
    return 0;
    
}