SPI spi(p5, p6, p7); // mosi(out), miso(in), sclk(clock)
DigitalOut cs(p8); // cs (the chip select signal)
Serial pc(USBTX, USBRX); 

int main() {
    
    spi.format(8,1); //(bits, mode) (mode1 (CPOL=0, CPHA=1)
    spi.frequency(1000000); //1MHz
    
    wait_ms(20);//Delay for minimum of 16ms to allow power supplies to settle and power-on reset to complete.
    
    cs = 0;// Select the device by seting chip select low
    wait_ms(1);//Delay for minimum of tsccs(=10ns)
    
    spi.write(0x06);//reset
    wait_ms(1);//Delay for minimum of 0.6ms
    
    spi.write(0x16);//SDATAC: Stop read data continuous mode.
    wait_ms(1);
    
    //WREG: Write to register rrrr
    spi.write(0x40);//WREG, MUX0
    spi.write(0x00);//
    spi.write(0x01);//AIN0 = + , AIN1 = -
    wait_ms(1);
    
    spi.write(0x42);//System Control Register0
    spi.write(0x00);//
    spi.write(0x30);//Internal Reference is always on. & Internal Reference selected.
    wait_ms(1);
    
    spi.write(0x43);//System Control Register0
    spi.write(0x00);//
    spi.write(0x12);//PGA=2, Data Output Rate = 20SPS
    wait_ms(1);
    
    spi.write(0x04);//SYNC: Synchronize ADC conversions.
    wait_ms(1);
    
    cs = 1;
    
    while(1) {
        cs = 0;
        spi.write(0x12);//RDATA: Read data once.
        wait_ms(1);
        
        unsigned char Volt_hex1 = spi.write(0xff);
        unsigned char Volt_hex2 = spi.write(0xff);
        unsigned short Volt_hex = (Volt_hex1 << 8) | Volt_hex2;
        float Volt = (float)Volt_hex / 0x7fff; //0 ~ 1.024V
        cs= 1;

        pc.printf("%f\r", Volt);
        wait(1);
    }
}