MCP3208 scipt

uint8_t *txbuf;
uint8_t *rxbuf;

int pin = 0;

void setup(void){
    static uint8_t _txbuf[8] __attribute__ ((section (".sram2")));
    static uint8_t _rxbuf[8] __attribute__ ((section (".sram2")));
    txbuf = _txbuf;
    rxbuf = _rxbuf;

    palSetPadMode(GPIOB,9,PAL_MODE_OUTPUT_PUSHPULL);
    palWritePad(GPIOB,9,1);
}

void loop(void){

    pin++;

    if (pin > 7){
        pin = 0;
    }
    else if (pin == 0){
        txbuf[0] = 0b01100000;  // = 0b01100000 = ADC CH0
        txbuf[1] = 0b00000000;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 1){
        txbuf[0] = 0b01100000;  // = 0b01100000 = ADC CH1
        txbuf[1] = 0b00000010;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 2){
        txbuf[0] = 0b01100000;  // = 0b01100000 = ADC CH2
        txbuf[1] = 0b00000001;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 3){
        txbuf[0] = 0b01100000;  // = 0b01100000 = ADC CH3
        txbuf[1] = 0b00000011;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 4){
        txbuf[0] = 0b11100000;  // = 0b01100000 = ADC CH4
        txbuf[1] = 0b00000000;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 5){
        txbuf[0] = 0b11100000;  // = 0b01100000 = ADC CH5
        txbuf[1] = 0b00000010;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 6){
        txbuf[0] = 0b11100000;  // = 0b01100000 = ADC CH6
        txbuf[1] = 0b00000001;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }
    else if (pin == 7){
        txbuf[0] = 0b11100000;  // = 0b01100000 = ADC CH7
        txbuf[1] = 0b00000011;  // = 0b00000000
        txbuf[2] = 0b00000000;  // = 0b00000000
    }

    palWritePad(GPIOB,9,0);
    spiSelect(&SPID1);      // START SPI
    spiSend(&SPID1,3,txbuf);
    spiReceive(&SPID1,3,rxbuf);
    spiUnselect(&SPID1);
    palWritePad(GPIOB,9,1);

    int z = (rxbuf[1] << 8| rxbuf[0]) << 16;

    if (pin == 0){
        PExParameterChange(&parent->PExch[PARAM_INDEX_y0_value],z,0xFFFD);
    }
    else if (pin == 1){
        PExParameterChange(&parent->PExch[PARAM_INDEX_y1_value],z,0xFFFD);
    }
    else if (pin == 2){
        PExParameterChange(&parent->PExch[PARAM_INDEX_y2_value],z,0xFFFD);
    }
    else if (pin == 3){
        PExParameterChange(&parent->PExch[PARAM_INDEX_y3_value],z,0xFFFD);
    }
    else if (pin == 4){

    }
    else if (pin == 5){

    }
    else if (pin == 6){

    }
    else if (pin == 7){

    }
    chThdSleepMilliseconds(1);

}