//-----------------------------------------------------------------------------
// Note
//  測定した電圧をシリアル通信で送信する。
//  PICの周波数を32Mhzに設定
//-----------------------------------------------------------------------------
#include <xc.h>
#include <stdio.h>
#include <stdlib.h>


// コンフィグレーションBIT1 設定
#pragma config FOSC = INTOSC    // Oscillator Selection (INTOSC oscillator: I/O function on CLKIN pin)
#pragma config WDTE = OFF       // Watchdog Timer Enable (WDT disabled)
#pragma config PWRTE = ON       // Power-up Timer Enable (PWRT enabled)
#pragma config MCLRE = OFF      // MCLR Pin Function Select (MCLR/VPP pin function is digital input)
#pragma config CP = OFF         // Flash Program Memory Code Protection (Program memory code protection is disabled)
#pragma config CPD = OFF        // Data Memory Code Protection (Data memory code protection is disabled)
#pragma config BOREN = OFF      // Brown-out Reset Enable (Brown-out Reset disabled)
#pragma config CLKOUTEN = OFF   // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)
#pragma config IESO = OFF       // Internal/External Switchover (Internal/External Switchover mode is disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is disabled)

// コンフィグレーションBIT2 設定
#pragma config WRT = OFF        // Flash Memory Self-Write Protection (Write protection off)
#pragma config PLLEN = ON       // PLL Enable (4x PLL enabled)
#pragma config STVREN = ON      // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)
#pragma config BORV = HI        // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), high trip point selected.)
#pragma config LVP = OFF        // Low-Voltage Programming Enable (High-voltage on MCLR/VPP must be used for programming)


#define _XTAL_FREQ 32000000

#define TX_UART_SIZE 3

//#define VOLTAGE_REFERENCE   5000
#define VOLTAGE_REFERENCE   4930
#define VOLTAGE_RESOLUTION  1024
//#define R1_OHM              10000
#define R1_OHM              9960
//#define R2_OHM              10000
#define R2_OHM              9960

volatile unsigned char uart_tx_msg[TX_UART_SIZE] = {0};
volatile unsigned char uart_tx_cnt = 0;


void interrupt isr_ctrl( void )
{
    if( TXIF )
    {
        if( uart_tx_cnt < TX_UART_SIZE )
        {
            TXREG = uart_tx_msg[ uart_tx_cnt ];
            uart_tx_cnt++;
        }
        else
        {
            TXIE = 0;
        }

        if( uart_tx_cnt >= TX_UART_SIZE )
        {
            uart_tx_cnt = 0;
            TXIE = 0;
        }

        TXIF = 0;
    }
}


int main(int argc, char** argv)
{
    unsigned short ad_data;
    long ad_volt,input_volt;
    short i,work1,work2,work3;

    OSCCON = 0b01110000 ;    // 内部クロック8ＭＨｚ

    ANSELA = 0b00010000 ;    // AN3をアナログにし、他はデジタルI/Oに割当てる
    TRISA  = 0b00011010 ;    // RA1,3,4を入力にし、他は出力に割当てる
    PORTA  = 0b00000000 ;    // 出力ピンの初期化(全てLOWにする)

    ADCON1 = 0b10100000 ;   // 右寄せ、Fosc/32,VDDをリファレンスにする

    ADCON0 = 0b00001101 ;   // AN3を使用する
    __delay_us(5);          // ch設定後、反映待ち

    TXSTA   = 0x24;     // 送信情報設定：非同期モード 8ビット・ノンパリティ
    RCSTA   = 0x90;     // 受信情報設定
    BAUDCON = 0x08;     // 16bit

    SPBRG  = 0x40;      // ボーレートを9600(高速モード)に設定
    SPBRGH = 0x03;

    RXDTSEL = 0;
    TXCKSEL = 0;

    TXIE    = 0;
    TXIF    = 0;
    PEIE    = 1;
    GIE     = 1;

    for(;;)
    {

        // AD 変換
        GO_nDONE = 1;   // 変換開始

        // アナログをデジタルに変換
        while( GO_nDONE )
        {
            // wait
        }

        ad_data = ADRESH;
        ad_data = (ad_data << 8) | ADRESL;

        // 計算
        ad_volt = ((long)VOLTAGE_REFERENCE * (long)ad_data) / VOLTAGE_RESOLUTION;
        input_volt = ad_volt * ((long)R1_OHM + (long)R2_OHM) / (long)R2_OHM;

        // 位で分割(小数点2桁を有効)
        work1 = input_volt / 10;
        work3 = work1 % 10;
        work1 /= 10;
        work2 = work1 % 10;
        work1 /= 10;

        // 送信データ構築
        uart_tx_msg[0] = 0x04;  // 少数点位置の設定
        uart_tx_msg[1] = 0x0f & work1;
        uart_tx_msg[2] = (work2<< 4) | work3;

        uart_tx_cnt = 0;
        TXIE = 1;               // 送信開始

        __delay_ms( 1000 );
    }

    return (EXIT_SUCCESS);
}