ADS124S06: Unable to read data on continuous mode, DRDY pin is being high all the time.

Good Morning Bryan Lizon86 , 

I'm not sure whether it is a hardware issue or a firmware issue, because both hardware and firmware working as expected Shortly after power-up, I can successfully read data from the ADC. I initiate conversions by pulling the START pin HIGH, and the data reads correctly. However, after a few conversions, the DRDY pin remains HIGH continuously, preventing further readings.

I’m not driving the DRDY pin—it's configured as an interrupt input triggered on its falling edge. Because DRDY stays HIGH, the interrupt never fires, halting data retrieval.

The firmware behaves as expected at startup and reads ADC data without issue initially. The problem only arises after a few conversions, suggesting the issue lies elsewhere-- maybe configuration or timing issues?

you can see the schematic 

Hi Pawan Kalyan,

Today is a national holiday in the US, please expect a response to your post in the next 1-2 days. Thanks for your patience.

-Bryan

Hi Pawan Kalyan,

You should be able to power up the ADC, pull the START pin high, then monitor the DRDY pin to see if the ADC is "alive". There is no need to send any commands to the ADC to get this behavior to work. This assumes that the ADC is powered correctly, the clock is working, and the RESET pin is high. You show a hand-drawn resistor to ground on the CLK pin, so I am not sure if this is something you added manually in your system or if this resistor was just included on a different schematic page. Either way, you should include at least a pull-down to ground if you intend to use the ADC internal oscillator. Also, if this is manually installed, recheck the connections / soldering. A poor clock signal could cause the issue you are describing

You can add a pull-up to the START pin so the ADC defaults to this behavior.

Let me know if you are able to continuously see the DRDY pin toggling at the default data rate (20 SPS, or ~50 Hz). Again, this should continue until you tell the ADC to stop converting. If you do not see this behavior then you have an issue with your power supply or clock, or both.

I would also add a pull-up to the RESET pin so the ADC starts in a known state

-Bryan

Hii Bryan Lizon86 , 

Bryan Lizon86 said:

You should be able to power up the ADC, pull the START pin high, then monitor the DRDY pin to see if the ADC is "alive".

This Works perfectly, ADC is alive. and drdyPin toggling continuously. 

void ADS124S06::ReadData(ADS124S06_Handle *dev, char *buf) {
	uint8_t tx_buf[1];
	tx_buf[0] = RDATA; // 0x12 START
	cs_low(dev);

	HAL_SPI_Transmit(dev->hspi, tx_buf, 1, 100);
	HAL_SPI_Receive(dev->hspi, rx_buf, 3, 100);

	cs_high(dev);
}

if I'm doing this, I'm able to read the data continuously. But I'm sending 0x12 command every time and receiving 24bit data. 

Whereas, in ADS124S08EVM I connected the logic analyser on SPI Lines, and I observed only once 0x12 command is being sent and able to read data on MISO line continuously.

When I tried to do the same with my firmware,

void ADS124S06::ReadData(ADS124S06_Handle *dev, char *buf) {
	static bool st = true;
	uint8_t tx_buf[1];
	tx_buf[0] = RDATA; // 0x12 START
	cs_low(dev);

	if(st)
	{
	    HAL_SPI_Transmit(dev->hspi, tx_buf, 1, 100);
	    st = false;
	}
	HAL_SPI_Receive(dev->hspi, rx_buf, 3, 100);

	cs_high(dev);
}

I'm facing an issue in readings. After capturing the few readings (morethan 2), Drdy pin is being high all the time.

Hi Pawan Kalyan,

Thanks for providing the requested information. I am glad you can confirm that the DRDY signal is working correctly at power up, and that you are able to read data when sending the RDATA command

Can you show us the communication on a logic analyzer to see if we can diagnose the issue? Please include CS, SCLK, DIN, DOUT, and DRDY. Please also show the data before, during, and after the issue occurs

Can you send us the ADC register settings you are using as well?

-Bryan

Hii Bryan Lizon86 , 

We analyzed the logic analyzer output for a single data transmission, and the captured data matches our expectations.

While monitoring the EVM SPI lines during sampling, we observed that the RDATA (0x12) command is issued only once after the START pin is pulled high. After that, the device continuously outputs conversion data until the specified sample count is completed, and then the START pin is pulled low.

However, in our case, the behavior is different. We are required to send the RDATA command repeatedly in order to receive continuous conversion data. If the RDATA command is not sent every time, no conversion data is received.

Hi Pawan Kalyan,

Can you send us the .sal file for the entire data transaction? Include good data, bad data, etc.. Please also include the START pin

I also don't see the RDATA command being issued at all on the ADS124S08EVM. I see that the START pin is pulled low all the time. This is necessary because the EVM is using the START/STOP commands to control conversions. I don't see any activity on DIN other than the START / STOP commands, which means the EVM is using the read data direct mode. Can you clarify what you are referring to in your last post? Are you using your own software to communicate with our EVM?

-Bryan

Hii Bryan Lizon86 , 

Bryan Lizon86 said:

I also don't see the RDATA command being issued at all on the ADS124S08EVM. I see that the START pin is pulled low all the time. This is necessary because the EVM is using the START/STOP commands to control conversions.

Yes, EVM is not sending any RDATA command instead they were sending START/STOP command while collecting the data. 

Bryan Lizon86 said:

I don't see any activity on DIN other than the START / STOP commands, which means the EVM is using the read data direct mode

Yes, NO Activity on DIN (MOSI) pin other than the START/STOP commands while collecting data. 

Bryan Lizon86 said:

Are you using your own software to communicate with our EVM?

No, we're using the Delta-Sigma ADC Evaluation Software only. 

Bryan Lizon86 said:

Can you clarify what you are referring to in your last post?

Yeah! In the previous post, I mentioned "While monitoring the EVM SPI lines during sampling, we observed that the RDATA (0x12) command is issued only once after the START pin is pulled high. After that, the device continuously outputs conversion data until the specified sample count is completed, and then the START pin is pulled low." On rechecking, I realized that this was my oversight in interpreting the EVM SPI data. The correct observation is that with the START pin kept low, the device transmits the START (0x08) command and STOP (0x0A) command on the DIN line to control the conversions.

I’m trying to figure out the right way to collect continuous data from the ADS124S06.

In my project:

• The ADC needs to collect data continuously from a sensor.

• The same SPI bus is shared with a display, and I’m handling this by using separate chip select (CS) pins for each device.

• Once powered up, the ADC should start continuous conversions and push the results into a queue for further processing.

So, my main question is:
What’s the recommended method to configure the ADS124S06 for continuous data collection over SPI while ensuring smooth operation alongside the display on the same bus?