ADS124S08EVM: Data collection problem in ADS124S08 EVM

Hi Sushmita,

As the red LED is lit (which is indicating that the START pin of the ADS124S08 is set high), the script appears to be executing.  Opening the Data Analysis and clicking on Collect should result in the collection of data for the number of points indicated (shown in the box under the Collect button.)  Prior to connecting the external voltage, I would try to run the script and from the Data Analysis screen Collect some data.

I'm thinking that perhaps there is a transient that is resetting the ADS124S08 when the external voltage is being connected and running the test I just outlined will help to determine what may be causing this issue.

What is the voltage you are applying and how do you have the input jumpers connected?

Best regards,

Bob B

Hello Bob,

I am supplying 6 V supply to J9 jumper,positive terminal of supply is connected to AIN10 and negative terminal to AINCOM.

After running the script,then I applied the external voltage,then opened data analysis tool and clicked collect button then also it was not coming.

So after running the script and gave power supply then I gave START command from console,then opened data analysis tool and pressed collect button,then I am able to collect the data. I don't know why it is happening.

Voltage across input mux will be the voltage across R77 resistance,that is for 6V  input supply it should come

VR77= Vin*(R77/(R76+R77))=6*(24/117.1)= 1.2294V

So 1.2294 V is coming in data analysis graph as Vout (input referred)

How we will check what digital value belongs to this analog value ??

Thanks

Regards

Sushmita Chaudhary

Hi Bob,

Yes it worked as you gave the instructions.Thank you.

Now I interfaced my arduino UNO with EVM and input as voltage source but whatever the output codes I am getting,it was not similiar codes in arduino. Here I am posting my code ,

#include <SPI.h>

#include <TimerOne.h>

#define START 6

#define RESET 7

#define CS 4

//#define DRDY 8

uint32_t stat;

uint32_t upperByte;

uint32_t middleByte;

uint32_t lowerByte;

uint8_t ADC_data[3];

int32_t signByte;

uint32_t stopping =0;

//volatile int DRDY_state = LOW;

SPISettings settings1(4000000, MSBFIRST, SPI_MODE1);

void setup() {

SPI.begin();

//pinMode(DRDY, INPUT);

pinMode(CS,OUTPUT);

pinMode(RESET, OUTPUT);

pinMode(START,OUTPUT);

digitalWrite(RESET , HIGH);

delay(5);

Serial.begin(9600);

SPI.beginTransaction(settings1);

digitalWrite(CS, LOW);

digitalWrite(START,LOW);

}

void loop() {

for(int i=0;i>=0;i++)

{

if(i==0){

SPI.transfer(0x42); // WREG register adress

SPI.transfer(0x07); // WREG byte number -1

SPI.transfer(0xAC); // WREG write AIN10-AINCOM,(1010 1100) binary,MUXP and MUXN selection

SPI.transfer(0x08); // gain =1

SPI.transfer(0x14); // DATA RATE 20 SPS

SPI.transfer(0x10); //REF

SPI.transfer(0x00); // IDAC MAG

SPI.transfer(0xFF); // IDAC MUX

SPI.transfer(0x00);// Vbias

SPI.transfer(0x12);// Timeout bit second =1 ,default is 10h

SPI.transfer(0x08); // start converting command

delay(1);

}

else

{

while(stopping < 5000)

{

digitalWrite(CS, LOW);

SPI.transfer(0x12); //RDATA command

ADC_data[0] = SPI.transfer(0) ;

ADC_data[1] = (ADC_data[0] <<8) | SPI.transfer(0);

ADC_data[2] = (ADC_data[1] <<8) | SPI.transfer(0);

digitalWrite(CS, HIGH);

stopping = millis();

//Sign extension code, 24 bit to 32 bit.

if(ADC_data[0]&0x80u){  

signByte = 0xFF000000;

}

else

{

signByte = 0x00000000;

}

upperByte=((int32_t) ADC_data[0] & 0xFF)<< 16;

middleByte=((int32_t) ADC_data[1] & 0xFF)<< 8;

lowerByte=((int32_t) ADC_data[2] & 0xFF)<< 0;

stat = (signByte | stat1 | stat2 | stat3);

Serial.print(stat);

Serial.print("\t");

Serial.print(stopping);

Serial.print("\n");

delay(200);// need an additional delay to allow the next conversion period to end.

}

}

}

SPI.endTransaction();

}

Can you suggest the changes?

Thank you!

Regards Bob

Hi Sushmita,

You are manipulating a lot of data by saving and shifting to various variables and you are using 'stat' as the variable you are printing, but to stat you are 'or'ing stat1, stat2 and stat3 which are never declared.

Some of the data you are saving as unsigned values and some of them are also unsigned bytes, such as the array ADC_data[].  Another issue is upperByte, middleByte and lowerByte are unsigned 32-bit, but you are casting an int32 which will not work.  As the variable 'stat' appears to be what you are most interested in, let's simplify and make this an int32_t instead of uint32_t.  When actually retrieving the data using the RDATA command there is no need to save to an array of bytes.  Instead:

SPI.transfer(0x12); //RDATA command

stat = SPI.transfer(0) ;

stat = (stat <<8) | SPI.transfer(0);

stat = (stat <<8) | SPI.transfer(0);

digitalWrite(CS, HIGH);


stopping = millis(); // I'm not sure what this does

//Sign extension code, 24 bit to 32 bit.

if(stat&0x800000){  

stat = stat | 0xFF000000;

}

Serial.print(stat);

//etc.

Just keep the code as simple and with as few of variables as possible.

Best regards,

Bob B