Data collection from ADS1298

To collect data from ADS1298 the previous setup will be used.

Data will be formatted. What is received from ADS1298: 3 bytes status + 8 groups of 3 bytes (for each channel).
Because value of each channel is 24-bit it will be manipulated to fit into 32-bit integer value.
Again, you need CLK and SCLK clock (both) to establish communication between RPi and ADS1298.
For plotting purposes first column of data will contain time stamps.

        
cpp
        

            
        
     

/*
 * Code to perform communication with ADS1298
 * 
 * ads1_1 - basic communication established. ADS gives an answer to Raspberry Pi B through SPI bus.
 * ads1.3 - read device signature, reset introduced, basic initial settings, generating test signal and printf of one channel and one value
 * ads1.4 - preparation for pipeing to continously give one channel value out
 * 
 * ads2.0 - seperated files, 'manual' control for /CS chip
 * ads2.1 - output now: saving to file (to allow use with kst2 - fast plotting program)
 * ads2.2 - time stamps
 * ads2.3 - volt values instead of numbers to be saved to file
 * ads2.4 - 8MHz SPI instead 4MHz
 * ---------------------------------------------------------------------------------------
 * *************Compile and build instruction for Geany/Raspberry Pi**********************
 * ---------------------------------------------------------------------------------------
 * to build: compile each of files seperately(from Geany), next: open terminal, cd to location where
 * all files live and type: gcc -o newname main.o adsCMD.o -lsbcm2835 
 * OR: check 'make' command in Geany 'Build'->'Set Build Command' to be something like:
 * gcc -o "%e" "%e.o" adsCMDfast.o -lbcm2835  Be sure to run it as Shift + F9
 * ---------------------------------------------------------------------------------------
 * 
 * Problems:
 * 
 */

#include <stdio.h>
#include <bcm2835.h>
#include <time.h> //for timestamps
#include "ads1298.h"
#include "adsCMDfast.h" //keeps pin assignment and basic IO operations


int main(int argc, char **argv){
 
    char buf[3] = {0,0,0};
    char bigbuf[27];
    char bigbuf2[27];
    int value1, value2, value3, value4, value5, value6, value7, value8; //ch1
    clock_t t, clockbegin;
    double voltvalue1, voltvalue2, voltvalue3, voltvalue4, voltvalue5, voltvalue6, voltvalue7, voltvalue8; 
 
 //saving to file
 FILE *pFile;
 
 if(!bcm2835_init()){
  printf("Oops, bcm2835 not initialised correctly\n");
  return 1;
 }
 
 if(!bcm2835_spi_begin()){ //_spi_begin returns 1 if spi_begin does its job with success
  printf("SPI not initialised correctly (Maybe you are not running as root?)\n");
  return 1;
 }

 bcm2835_spi_chipSelect(BCM2835_SPI_CS_NONE); //do NOT set any /CS automatically
 //pins setup:
 bcm2835_gpio_fsel(LEDPIN, BCM2835_GPIO_FSEL_OUTP); //LED pin output
 bcm2835_gpio_fsel(RESETPIN, BCM2835_GPIO_FSEL_OUTP); //RESETPIN as output
 bcm2835_gpio_fsel(STARTPIN, BCM2835_GPIO_FSEL_OUTP); //STARTPIN as output
 bcm2835_gpio_fsel(CS_PIN, BCM2835_GPIO_FSEL_OUTP); //CS is an output
 bcm2835_gpio_fsel(DRDYPIN, BCM2835_GPIO_FSEL_INPT); //DRDY input
 //bcm2835_gpio_set_pud(DRDYPIN, BCM2835_GPIO_PUD_UP); //DRDY pull-up
 
 //reset high
 bcm2835_gpio_write(RESETPIN, HIGH);
 
 //START low
 bcm2835_gpio_write(STARTPIN, LOW);
 
 //bit order
 bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST);
 
 //Set CS pin polarity to low (LOW when CS active)
 //bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0, 0);
 
 //Set which CS pin to use for next transfers
 //bcm2835_spi_chipSelect(BCM2835_SPI_CS0);

 //Set SPI clock speed
 // BCM2835_SPI_CLOCK_DIVIDER_65536 = 0,       ///< 65536 = 262.144us = 3.814697260kHz (total H+L clock period) 
 // BCM2835_SPI_CLOCK_DIVIDER_32768 = 32768,   ///< 32768 = 131.072us = 7.629394531kHz
 // BCM2835_SPI_CLOCK_DIVIDER_16384 = 16384,   ///< 16384 = 65.536us = 15.25878906kHz
 // BCM2835_SPI_CLOCK_DIVIDER_8192  = 8192,    ///< 8192 = 32.768us = 30/51757813kHz
 // BCM2835_SPI_CLOCK_DIVIDER_4096  = 4096,    ///< 4096 = 16.384us = 61.03515625kHz
 // BCM2835_SPI_CLOCK_DIVIDER_2048  = 2048,    ///< 2048 = 8.192us = 122.0703125kHz
 // BCM2835_SPI_CLOCK_DIVIDER_1024  = 1024,    ///< 1024 = 4.096us = 244.140625kHz
 // BCM2835_SPI_CLOCK_DIVIDER_512   = 512,     ///< 512 = 2.048us = 488.28125kHz
 // BCM2835_SPI_CLOCK_DIVIDER_256   = 256,     ///< 256 = 1.024us = 976.5625MHz
 // BCM2835_SPI_CLOCK_DIVIDER_128   = 128,     ///< 128 = 512ns = = 1.953125MHz
 // BCM2835_SPI_CLOCK_DIVIDER_64    = 64,      ///< 64 = 256ns = 3.90625MHz
 // BCM2835_SPI_CLOCK_DIVIDER_32    = 32,      ///< 32 = 128ns = 7.8125MHz
 // BCM2835_SPI_CLOCK_DIVIDER_16    = 16,      ///< 16 = 64ns = 15.625MHz
 // BCM2835_SPI_CLOCK_DIVIDER_8     = 8,       ///< 8 = 32ns = 31.25MHz
 // BCM2835_SPI_CLOCK_DIVIDER_4     = 4,       ///< 4 = 16ns = 62.5MHz
 // BCM2835_SPI_CLOCK_DIVIDER_2     = 2,       ///< 2 = 8ns = 125MHz, fastest you can get
 // BCM2835_SPI_CLOCK_DIVIDER_1     = 1,       ///< 1 = 262.144us = 3.814697260kHz, same as 0/65536
 bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_32);

 //Set SPI data mode
 // BCM2835_SPI_MODE0 = 0,  // CPOL = 0, CPHA = 0, Clock idle low, data clocked in on rising edge, output data (change) on falling edge
 // BCM2835_SPI_MODE1 = 1,  // CPOL = 0, CPHA = 1, Clock idle low, data clocked in on falling edge, output data (change) on rising edge
 // BCM2835_SPI_MODE2 = 2,  // CPOL = 1, CPHA = 0, Clock idle high, data clocked in on falling edge, output data (change) on rising edge
 // BCM2835_SPI_MODE3 = 3,  // CPOL = 1, CPHA = 1, Clock idle high, data clocked in on rising, edge output data (change) on falling edge
 bcm2835_spi_setDataMode(BCM2835_SPI_MODE1);

 bcm2835_gpio_write(LEDPIN, LOW);
  
 //reset the device
 bcm2835_gpio_write(RESETPIN, LOW);
 delay(1);
 bcm2835_gpio_write(RESETPIN, HIGH);
 delay(150);//wait  (0.128s required)
  
 buf[0]=(RREG | ID);
 buf[1]=0;
 buf[2]=0;
 
 cs_select(); 
 bcm2835_spi_transfer(SDATAC); //stop read data continuous mode SDATAC
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();
 
 cs_select(); 
 bcm2835_spi_transfern(buf, 3);
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();


 bcm2835_gpio_write(RESETPIN, LOW);
 delay(1);
 bcm2835_gpio_write(RESETPIN, HIGH);
 delay(250);

 cs_select();
 bcm2835_spi_transfer(SDATAC); //SDATAC=0x11
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();
 
 //send WREG CONFIG3 0xC0 - sets 7th and 6th bit of CONFIG3 (/PD_REFBUF and bit6) to 1 - internal reference
 adc_wreg(CONFIG3, 0xC0); //wreg = 0x40 | registry -> CONFIG3 = 0x03, 0xC0, so sending 0x43, 0x00, 0xC0 sent ok
 delay(1);
 
 //set device in HR mode and DR=fMOD/1024
 //WREG CONFIG1 0x86 sets HR, DR2 and DR1 bits in CONFIG1 registry(Arduino does HR, DR2, DR0, this would be 0x85 -> 1000 0101)
 //CONFIG1 bit 7 changes HR (when 1) to LowPower (when set to 0)
 //CONFIG1 setup the data rate in DR[2:0] - 
 //three LSB bits  (110 - fMOD/1024 = 500SPS in HR mode and 250SPS in LP mode)
 //     (101 - fMOD/512  = 1kSPS  in HR   and 500SPS in LP mode)
 //     (100 - fMOD/256  = 2kSPS  in HR
 //     (...)
 //     (010 - fMOD/64  = 8kSPS  in HR    4kSPS in LP mode)
 // RESET STATE OF CONFIG1 is 0000 0110 which is: LP mode, fMOD/1024
 // modes of fMOD/32 and fMOD/16 makes 16kSPS and 32kSPS, but in resolution of 19-bit and 16-bit (higher bits can be ignored in these cases)
 //adc_wreg(CONFIG1, 0x86); // 0x40|reg => 0x41 0x00 0x86 --> 1000 0110 => HR mode, 500SPS
 adc_wreg(CONFIG1, 0x85); //1000 0101 => HR mode, 1kSPS
 
 //WREG CONFIG2 0x00 dont set any bits in CONFIG2 registry
 adc_wreg(CONFIG2, 0x00); // 0x40|reg => 0x42 0x00 0x00
 
 //set all channels to input short
 //WREG CHnSET 0x01
 for(int i=1; i<=8;++i){
  adc_wreg(CHnSET + i, 0x01); 
 }
 
 //set pin START = 1
 bcm2835_gpio_write(STARTPIN, HIGH); //monitor STARTPIN

 //send RDATAC
 cs_select();
 bcm2835_spi_transfer(RDATAC); //0x10
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();
 
 //look for DRDY and issue 24+n*24SCLKs
 while ((bcm2835_gpio_lev(DRDYPIN))==HIGH){ //wait for HIGH on DRDY
 }
 cs_select();
 bcm2835_spi_transfern(bigbuf, 27); //this would measure noise
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();

 bcm2835_gpio_write(STARTPIN, LOW); //monitor STARTPIN and confirm.... ok, present
 
 cs_select();
 bcm2835_spi_transfer(SDATAC);//stop data
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect(); 

 adc_wreg(CONFIG2, 0x00); //for external data collection

 cs_select();
 char tempspibuf[3] = {0,0,0};
 tempspibuf[0]=0x41; //write to CONFIG1
 tempspibuf[1]=0;
 tempspibuf[2]=0x85; //value to write
 
 bcm2835_spi_transfern(tempspibuf, 3);
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect();
 //end of settings for higher SPS
 
 for(int i=1; i<=8;++i){
  adc_wreg(CHnSET + i, 0x10); //Every channel has to be set seperately
  //x00 --> 0000 0000 = Normal electrode inputs, 6x gain
  //b 0 001 0 000 => 0x10 normal input, 1x gain 
 }

 bcm2835_gpio_write(STARTPIN, HIGH); //START signal
 
 cs_select();
 bcm2835_spi_transfer(RDATAC);//0x10 confirmed
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect(); 
 clockbegin=clock(); //start timestamps
 while(1){
  for(int k=0;k<27; k++) bigbuf2[k] = 0; //clear the buffer
  while (bcm2835_gpio_lev(DRDYPIN)==HIGH){ }
  t=clock()-clockbegin;
  double time_stamp = ((double)t)/CLOCKS_PER_SEC;
  cs_select();
  bcm2835_spi_transfern(bigbuf2, 27);
  bcm2835_delayMicroseconds(CS_DELAY);
  cs_deselect(); 
  if(bigbuf2[0]==0b11000000){//kind of crc.. always 192 -> 1100 0000
   value1 = ((bigbuf2[3] << 24)|(bigbuf2[4] << 16)|(bigbuf2[5]<<8>>8;
   value2 = ((bigbuf2[6] << 24)|(bigbuf2[7] << 16)|(bigbuf2[8]<<8>>8;
   value3 = ((bigbuf2[9] << 24)|(bigbuf2[10] << 16)|(bigbuf2[11]<<8>>8;
   value4 = ((bigbuf2[12] << 24)|(bigbuf2[13] << 16)|(bigbuf2[14]<<8>>8;
   value5 = ((bigbuf2[15] << 24)|(bigbuf2[16] << 16)|(bigbuf2[17]<<8>>8;
   value6 = ((bigbuf2[18] << 24)|(bigbuf2[19] << 16)|(bigbuf2[20]<<8>>8;
   value7 = ((bigbuf2[21] << 24)|(bigbuf2[22] << 16)|(bigbuf2[23]<<8>>8;
   value8 = ((bigbuf2[24] << 24)|(bigbuf2[25] << 16)|(bigbuf2[26]<<8>>8; 
   //3 seperate bytes into one 32-bit signed integer value
  }
  
  //else printf("f");
  voltvalue1 = value1*0.00000029802326;
  voltvalue2 = value2*0.00000029802326;
  voltvalue3 = value3*0.00000029802326;
  voltvalue4 = value4*0.00000029802326;
  voltvalue5 = value5*0.00000029802326;
  voltvalue6 = value6*0.00000029802326;
  voltvalue7 = value7*0.00000029802326;
  voltvalue8 = value8*0.00000029802326;
  pFile=fopen("voltdatafast.dat","a"); //open file to append(file is created if it doesn't exist)
  if(pFile==NULL){
   perror("Error opening file");
  }
  else {
   fprintf(pFile,"%f %f %f %f %f %f %f %f %f\n", time_stamp, voltvalue1, voltvalue2, voltvalue3, voltvalue4, voltvalue5, voltvalue6, voltvalue7, voltvalue8);
  }
  fclose(pFile);
 }
 cs_select();
 bcm2835_spi_transfer(SDATAC);
 bcm2835_delayMicroseconds(CS_DELAY);
 cs_deselect(); 
 //Return SPI pins to default input state
 bcm2835_spi_end();
  
 return 0;
}

Check the code before compiling, the code syntax highlighter does some weird stuff sometimes on this webpage.

There is a need to add these additional files (#include ... from beginning of the file), but posting here is tricky, so I have started github project: https://github.com/VikingsCat/ads1298