HOW TO PROGRAM 24 BIT ADC CS5532/34 with PIC 18f4550 MCU C18

In some particular application regular ADC units will not be enough. Because of the relativly small resolution (e.g. 10 or 8 bit) regular ADCs will not satisfy your demand. In this situation I am using CS5532/34 from Cirrus Logic. It has a stunning resolution of 24 bit. The problem is to program this unit is hard. There is not any example code for Microchip MPLAB C18. I have written an example code for Pic MCUs. Here I am sharing this codes for your help. 

Let's began with assigning the prototypes:

/**PROTOTYPES*******************************************************************************/
void csadc_init(void);//16/24bit adc başlat
void csadc_set(void);//6/24bit adc kanal ayarları
void csadc_read(char channel);//6/24bit adc okuma

The function called csadc_init() is the code that makes first initialization of the ADC IC.

void csadc_init(void)
{

    int i;
    ADC_CS=0;   
    OpenSPI(SPI_FOSC_64 ,MODE_00,SMPMID);//set the SPI module to communicate with the ADC.

     for(i=0; i<15 i="" span="" style="color: #666666;">//according to the data sheet the first thing you need to do is sending 15 sync1 code which is 0xFF.

     {
        //SPI başlatılmalı. Kontrol et.
        GonderAlSpi(0xFF);
    }
        GonderAlSpi(0xFE);//now you need to send sync1 code which is 0xFE.
//Now we will write 1 to the reset bit of the configuration register. This is going to reset the ADC.
//we need to write whole 32 bit of the configuration register.
       GonderAlSpi(0x03);//Write configuration register command 

    GonderAlSpi(0x20);//set the 29th bit (RS bit) ofthe configuration register.
       GonderAlSpi(0x00);
       GonderAlSpi(0x00);
       GonderAlSpi(0x00);

Delay10TCYx (25);//wait for 20us. I am running the MCU at 48MHz 

//Now we need to make RS bit 0 again.
    GonderAlSpi(0x03);//Write configuration register command         GonderAlSpi(0x00);//reset the 29th bit (RS bit) of the configuration register.    

    GonderAlSpi(0x00);
    GonderAlSpi(0x00);
    GonderAlSpi(0x00);
ADC_CS=1;
csadc_set();//I call this funtion to setup the channel setup register 1 for the next step.
} 

The function called csadc_set() is the function that set the channel setup registers. Here I am leaving the whole setting as default. 

void csadc_set(void)//Setting the channel setup register.
{
    ADC_CS=0;
    GonderAlSpi(0x05);//Channel setup1 command
    GonderAlSpi(0x04);//Channel1
    GonderAlSpi(0xC0);
    GonderAlSpi(0x44);//channel2
    GonderAlSpi(0xC0);
    ADC_CS=1;
} 

Now is the time to write the reading code. The function below select the phyisical channel 1 for channel=1 and physical channel 2 for the channel=2.

void csadc_read(char channel)
{

    ADC_CS=0;
if(channel==1)
{
    GonderAlSpi(0x80);//select channel 1
}
else
{
    GonderAlSpi(0x88);//select channel 2
}

Delay100TCYx (250);
Delay100TCYx (250);
    GonderAlSpi(0x00);//clear the SDO flag
    v1=GonderAlSpi(0x00);//MSB of the ADC data
    v2=GonderAlSpi(0x00);
    v3=GonderAlSpi(0x00);//LSB of the ADC data
    v4=GonderAlSpi(0x00);//here there is some information. don't use them.
    ADC_CS=1;
   ToSendDataBuffer[adcrmsreg] = v1;//Your data now in the data buffer to be sent via USB.
    ToSendDataBuffer[adcrmsreg+1] =v2;
    ToSendDataBuffer[adcrmsreg+2] =v3;
    ToSendDataBuffer[adcrmsreg+3] =v4;
//bundan sonra veriyi göndereceğim
}

The function below is the function that send and get data via SPI

unsigned char GonderAlSpi(unsigned char data)

{
SSPBUF=data;
while(!SSPSTATbits.BF);
return SSPBUF;
} 

Now we will call the functions in the main function

void main(void)
#else
int main(void)
#endif
{
   InitializeSystem();    
   Delay100TCYx (250);//wait for a little time to make sure the MCU stabilized.
    csadc_init();//İnitialize the ADC
    #if defined(USB_INTERRUPT)
        USBDeviceAttach();
    #endif

    while(1)
    {
        #if defined(USB_POLLING)
        // Check bus status and service USB interrupts.
        USBDeviceTasks(); // Interrupt or polling method.  If using polling, must call
                          // this function periodically.  This function will take care
                          // of processing and responding to SETUP transactions
                          // (such as during the enumeration process when you first
                          // plug in).  USB hosts require that USB devices should accept
                          // and process SETUP packets in a timely fashion.  Therefore,
                          // when using polling, this function should be called
                          // frequently (such as once about every 100 microseconds) at any
                          // time that a SETUP packet might reasonably be expected to
                          // be sent by the host to your device.  In most cases, the
                          // USBDeviceTasks() function does not take very long to
                          // execute (~50 instruction cycles) before it returns.
        #endif
                    

        // Application-specific tasks.
        // Application related code may be added here, or in the ProcessIO() function.
         
          
         ProcessIO();      
    }//end while
}//end main 

Now you are ready to make conversion. I have used the case 0x37 in the ProcessIO() function.

case 0x37:   

{       

if(!HIDTxHandleBusy(USBInHandle))

{
 csadc_read(1);//read channel 1

ToSendDataBuffer[5] = v4;      //Measured analog voltage LSB

ToSendDataBuffer[6] = v3;      //

ToSendDataBuffer[7] = v2;      //

ToSendDataBuffer[8] = v1;      //Measured analog voltage MSB

csadc_read2);//read channel 2
ToSendDataBuffer[1] = v4;      //Measured analog voltage LSB

ToSendDataBuffer[2] = v3;      //

ToSendDataBuffer[3] = v2;      //

ToSendDataBuffer[4] = v1;      //Measured analog voltage MSB
                    

USBInHandle = HIDTxPacket(HID_EP,(BYTE*)&ToSendDataBuffer[0],64);

}                    

}

Now your converted data is in the ToSendDataBuffer array and ready to be sent via USB.