Cần giúp giao tiếp SPI giữa PIC16f877a và MCP4822

[barcelonafan_va]

E đang làm giao tiếp giữa PIC16f877a với con DAC MCP4822 mà nó chưa chạy. Dưới đây là đoạn code của e, các bác nào phát hiện ra chỗ sai thì giúp e với. Thank các bác nhiều
//Main
void main(void)
{
//int16 data;
//int i;
/*setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_CLOCK_DIV_2);
setup_psp(PSP_DISABLED);
setup_spi(SPI_SS_DISABLED);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);

// TODO: USER CODE!!*/
TRISB = 0x00;
PORTB = 0x04;

//TRISA = 0x00;
//PORTA = 0x00;

TRISC = 0x00;
PORTC = 0x00;

int_SPI();
//setup_spi(spi_master |spi_l_to_h |spi_clk_div_4 );


while(1)
{
DACOut(1,2,1900);
DACOut(0,2,3800);
}

}


//Khoi tao cho SPI
void int_SPI(void)
{
//CS = 1;
//SSPSTAT = 0xC0; // Status Register SSPSTAT=11000000
//SSPCON = 0x20; // Enables serial port pins & set the SPI clock as clock = FOSC/4
// set_tris_c(0b11010011); // sck rc3-0, sdo rc5-0, CS rc2-0.

STAT_SMP=0;
STAT_CKE=0;
CKP=1;
//SSPM1=1;
SSPM0=1;
SSPEN=1;
}


void SPIOut(char data)
{
SSPBUF=data; //transmite one byte
while (!STAT_BF); //cho den khi bit SPIF duoc set, qua trinh truyen ket thuc
// return SSPBUF;
}

//***for MCP4822******************************************* *******************
void DACOut(unsigned int ch, unsigned int gain, int16 data)
{
//ch: channel 0 la kenh A va 1 la kenh B, gain =1 hoac 2, data 14 bit
unsigned int Hcmd, Lcmd, G, Hdata;
//(gain==1)? (G=1): (G=0); //chon bit gain, G
if(gain ==1){G=1;}
else G=0;
Hdata=(data>>8) & 0x0F; //Hdata is 4 MSB bits of data
ch &=0x01;
Hcmd=(ch<<7)|(G<<5)|(1<<4)|Hdata; //chu y la bit Shut down phai duoc set

Lcmd=(unsigned char) (data);
//send SPI
CS = 0;
SPIOut(Hcmd); //goi byte cao
SPIOut(Lcmd); //goi byte thap
CS = 1;
}
//***end of MCP4822******************************************* ***************