ADS131A02: Initialization Issue

Hello Neha,

Thank you for your post and welcome to our forum!

Are you referring to Figure 106? During the initialization of the ADS131A02, the device cannot accept any commands until it is unlocked. "Reset" is mentioned in the fourth step to describe the status of the /RESET pin. This is meant to indicate that the /RESET pin should be high in order to initialize the device. You can use a pull-up resistor to connect /RESET to the digital supply so that it can ramp with the power supplies on your board. Can you check the /RESET pin after power-up and verify that it is high?

The device should send the READY word automatically after the power supplies have ramped. You do not need to send any commands in order to see the READY word.

*Edited 7/6/18: technically, the NULL command must be sent on DIN in order for the READY word to appear on DOUT*

Best Regards,

Hello Ryan,

Yes exactly, I am talking about figure 106. Currently RESET pin is pulled up to 3.3V(D) supply using a 10K resistor.

Now according to you, I don't need to send any RESET command as ADC will automatically RESET when powered on. I just have to monitor READY word. 

Am I getting right?

Now I have checked the RESET pin on scope. Ideally it is low, as I powered on the device it goes high & then remains high.

Hi Ryan,

I have tried the same way but failed to get READY response. DOUT pin is continuously high.

Kindly check the attached files & inform me if m doing something wrong.

#include �adc.h�

void uiADC_WriteADCWord(uint32_t uiWordData)
{
       uint8_t ucLoop=0;
	defADC_ClrPinSCLK;
	vDelay(2);
	vSPI1_EnableSlave();
	vDelay(2);
	for(ucLoop=0;ucLoop<24;ucLoop++)
	{
		defADC_SetPinSCLK;
		vDelay(2);
		if((uiWordData & 0x800000) == 0x800000)
		{
			defADC_SetPinDIN;
		}
		else
			defADC_ClrPinDIN;
		vDelay(5);
		defADC_ClrPinSCLK;
		vDelay(2);
		uiWordData = uiWordData << 1;	// Shift Left by 1 bit
	}
	vSPI1_DisableSlave();
	vDelay(2);
}

uint32_t uiADC_ReadADCWord(void)
{
	uint8_t ucLoop=0;
	uint16_t uiWordData=0;
	defADC_ClrPinSCLK;
	vDelay(2);
	vSPI1_EnableSlave();
	vDelay(2);
	for(ucLoop=0;ucLoop<24;ucLoop++)
	{
		uiWordData = uiWordData<<1;
		defADC_SetPinSCLK;
		vDelay(2);
		uiWordData = uiWordData | defADC_GetPinStatusDOUT;
		vDelay(5);
		defADC_ClrPinSCLK;
		vDelay(2);
	}
	vSPI1_DisableSlave();
	vDelay(2);
	return uiWordData;
}

void vADC_Init(void)
{
	GPIO_InitTypeDef			GPIO_InitStructure;

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	GPIO_InitStructure.GPIO_Pin 	= defADC_SCLKPin | defADC_DINPin | defADC_CSPin;
	GPIO_InitStructure.GPIO_Speed 	= GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode	= GPIO_Mode_Out_PP;
	GPIO_Init(defADC_SPIPort, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin 	= defADC_DOUTPin;
	GPIO_InitStructure.GPIO_Speed 	= GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode 	= GPIO_Mode_IPU;
	GPIO_Init(defADC_SPIPort, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin = defADC_CLKPin;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_Init(defADC_SPIPort, &GPIO_InitStructure);

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
	GPIO_InitStructure.GPIO_Pin 	= defADC_DRDYPin | defADC_DONEPin;
	GPIO_InitStructure.GPIO_Speed 	= GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode 	= GPIO_Mode_IPU;
	GPIO_Init(defADC_ControlPort, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin 	= defADC_RESETPin;
	GPIO_InitStructure.GPIO_Speed 	= GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode 	= GPIO_Mode_Out_PP;
	GPIO_Init(defADC_ControlPort, &GPIO_InitStructure);

	RCC_MCOConfig(RCC_MCO_HSI);     				//RCC_MCO_HSI
	vSPI1_DisableSlave();
	vDelay(5);
	vSPI1_EnableSlave();
}



void vSPI1_EnableSlave(void)
{
	// Set slave CS pin low
	defADC_SPIPort->BRR = defADC_CSPin;
}
void vSPI1_DisableSlave(void)
{
	// Set slave CS pin high
	defADC_SPIPort->BSRR = defADC_CSPin;
}

#include "main.h"

uint8_t   adc_flag=0;

int main(void)
{
	uint32_t response=0;
	SystemInit();                          		// To set mcu clock
	vADC_Init();
	systick_Init();
	adc_flag = 1;
    	while(1)
    	{
    		if(adc_flag==1)
    		{
    			while(!(response == 0xff0200))
    			{
    				response = 0;
    				uiADC_WriteADCWord(0x000000);
    				response = uiADC_ReadADCWord();
    		}
    		uiADC_WriteADCWord(0x065500);
    		response = uiADC_ReadADCWord();
    		adc_flag = 0;
    	}
    }
}

Hi Neha,

Is it possible to capture two consecutive data frames with an oscilloscope? The first should show the NULL command being sent, and the second should show the ADC response. Please probe SCLK, DIN, DOUT.

Also, how are M0 and M2 configured? If you have Hamming Code enabled, please try disabling it by tying M2 to ground.

Best Regards,

Hello Ryan,

M0 & M1 are grounded while M2 is connected with IOVdd pin (i.e. 3.3V Digital). I have sent NULL command (0x000000) at DIN & captured ADC response. I am still receiving 0xffffff at DOUT.

Kindly check the scope traces & provide me a solution.

Also check my hardware.

Hello Neha,

Thanks for sharing the scope captures. I understand it may be difficult to capture consecutive frames together (i.e. UNLOCK command + NULL command to see the response). From what I can tell, 0x000000 is written to DIN and you see only 0xFFFFFF on DOUT. If this is consistent with what you see every frame, then there is certainly an issue.

One thing that I just noticed is that your SCLK does not appear to have a 50/50 duty cycle. Can you verify the SCLK frequency and high/low times for me? They must agree with the Timing Requirements in Table 7.6:

Best Regards,

Hi Neha,

Please confirm the M0, M1, and M2 settings again. I just realized that your schematic drawing does not match was you wrote in your earlier reply:

neha yadav said:

M0 & M1 are grounded while M2 is connected with IOVdd

Best Regards,

Hello Ryan,

I wrote wrong earlier. M0, M1 & M2 are as per schematic drawing.

M0 is connected with IOVdd while M1 & M2 are grounded.

Hello Ryan,

If you have any sample code for this ADC, kindly provide me that.

I have tried to communicate with 1 device.

Hi Neha,

Please try one or two more devices if you can.

May I contact you at the email address in your profile?

Regards,

Hello Ryan,

Yes I will try one more device tomorrow and will let you know the response.

Yes you can contact me at ydv95neha@gmail.com .

Hello Ryan,

I tried another device also. But I got same results.

Kindly suggest something as it has already consumed a lot of time.