AD7799应用程序

小西北

                                                            /* basic driver for ad7798 and ad7799, not all functions supported

   assumes a spi driver exists, and "spi_transfer" takes

   and returns a byte. */



#define AD7799_STATUS_RDY       0x80

#define AD7799_STATUS_ERROR     0x40

#define AD7799_STATUS_NOREF     0x20

#define AD7799_STATUS_IS_AD7799 0x08

#define AD7799_STATUS_CHAN_MASK 0x07



static uint8_t ad7799_init_status;



#define AD7799_STATUS_REG 0x0

#define AD7799_MODE_REG   0x1

#define AD7799_CONFIG_REG 0x2

#define AD7799_DATA_REG   0x3

#define AD7799_ID_REG     0x4

#define AD7799_IO_REG     0x5

#define AD7799_OFFSET_REG 0x6

#define AD7799_SCALE_REG  0x7



static void ad7799_reset(void)

{

   int i;

   for(i = 0; i<4; i++)

      spi_transfer(0xff);

}



/* helper request function */

static inline void ad7799_comm(uint8_t reg, uint8_t read, uint8_t cont)

{

   spi_transfer((read ? 0x40 : 0x00) | (reg << 3) | (cont ? 0x04 : 0x00));

}



/* return the contents of the OFFSET register */

int32_t ad7799_read_offset(void)

{

   ad7799_comm(AD7799_OFFSET_REG, 1, 0);

   int32_t val = 0;

   if(ad7799_init_status & AD7799_STATUS_IS_AD7799)

      val |= (int32_t)spi_transfer(0) << 16;

   val |= (int32_t)spi_transfer(0) << 8;

   val |= (int32_t)spi_transfer(0);

   return val;

}



/* return the contents of the FULL-SCALE register */

int32_t ad7799_read_scale(void)

{

   ad7799_comm(AD7799_SCALE_REG, 1, 0);

   int32_t val = 0;



   if(ad7799_init_status & AD7799_STATUS_IS_AD7799)

      val |= (int32_t)spi_transfer(0) << 16;

   val |= (int32_t)spi_transfer(0) << 8;

   val |= (int32_t)spi_transfer(0);

   return val;

}



uint8_t ad7799_status(void)

{

   ad7799_comm(AD7799_STATUS_REG, 1, 0);

   return spi_transfer(0);

}



/*  Setting the mode, pick one for mode and rate,

    psw is either zero or non-zero */

enum { AD7799_CONTINUOUS_CONVERSION_MODE = 0,  AD7799_SINGLE_CONVERSION_MODE,

       AD7799_IDLE_MODE, AD7799_POWERDOWN_MODE, AD7799_INTERNAL_OFFSET_CAL_MODE,

       AD7799_INTERNAL_SCALE_CAL_MODE,  AD7799_SYSTEM_OFFSET_CAL_MODE,

       AD7799_SYSTEM_SCALE_CAL_MODE};



enum { AD7799_470_HZ = 1, AD7799_242_HZ, AD7799_123_HZ, AD7799_62_HZ,

       AD7799_50_HZ, AD7799_39_HZ, AD7799_33_2_HZ, AD7799_19_6_HZ,

       AD7799_16_7_1_HZ, AD7799_16_7_2_HZ, AD7799_12_5_HZ, AD7799_10_HZ,

       AD7799_8_33_HZ, AD7799_6_25_HZ, AD7799_4_17_HZ };



void ad7799_set_mode(uint8_t mode, uint8_t psw, uint8_t rate)

{

    ad7799_comm(AD7799_MODE_REG, 0, 0);

    spi_transfer(mode << 5 | (psw ? 0x10 : 0x00));

    spi_transfer(rate);

}



/* setting config, pick gain and chan from below,

   the rest are either zero or non-zero */

enum { AD7799_1_GAIN, AD7799_2_GAIN, AD7799_4_GAIN, AD7799_8_GAIN,

       AD7799_16_GAIN, AD7799_32_GAIN, AD7799_64_GAIN, AD7799_128_GAIN };

enum { AD7799_AIN1_CHAN, AD7799_AIN2_CHAN, AD7799_AIN3_CHAN,

       AD7799_AIN11_CHAN, AD7799_AVDD_CHAN };



void ad7799_write_config(uint8_t burnout, uint8_t unipolar, uint8_t gain,

                          uint8_t ref_det, uint8_t buf, uint8_t chan)

{

   ad7799_comm(AD7799_CONFIG_REG, 0, 1);

   spi_transfer((burnout ? 0x40 : 0x00) | (unipolar ? 0x20 : 0x00) | gain);

   spi_transfer((ref_det ? 0x20 : 0x00) | (buf ? 0x10 : 0x00) | chan);

}



/* determine if data is ready to be read, could also be

   implemented by reading the status register */

int8_t ad7799_data_ready(void)

{

   return !(PINB & _BV(DD_MISO));

}



/* request a read from the data register */

void ad7799_request_data(uint8_t continuous)

{

   ad7799_comm(AD7799_DATA_REG, 1, continuous);

}



/* read from data register, it should be previously requested

   from ad7799_request_data, the value is signed */

int32_t ad7799_read_data(void)

{

   uint32_t val = 0;



   if(ad7799_init_status & AD7799_STATUS_IS_AD7799) {

      val = spi_transfer(0);

      val <<= 8;

   }



   val |= spi_transfer(0);

   val <<= 8;

   val |= spi_transfer(0);



   if(ad7799_init_status & AD7799_STATUS_IS_AD7799)

      return val - 0x800000;



   return val - 0x8000;



}



void ad7799_calibrate()

{

   int32_t off = ad7799_read_offset();

   printf("offset: 0x%lx\n", off);



   /* cal */

   ad7799_set_mode(AD7799_INTERNAL_OFFSET_CAL_MODE, 0, AD7799_16_7_1_HZ);

   while(!ad7799_data_ready());



   off = ad7799_read_offset();

   printf("offset: 0x%lx\n", off);

}



void ad7799_init()

{

   ad7799_reset();

   ad7799_init_status = ad7799_status();

}

         

dainqi10

我也在调 参考下

小西北

symcu

万能的论坛，想要的一搜就有！顶