Diagnostic feature for AFE4490 / AFE4400

Praveen Aroul

Mastermind 49176 points

Other Parts Discussed in Thread: AFE4490, AFE4400

Shorting TP17 to TP25 (i.e., shorting TXN to GND) on the AFE4490SPO2EVM / AFE4400SPO2EVM produce a fixed freq sound, the blue indicator light becomes dark on the EVM and PC GUI crashes.
Shorting TP23 to TP25 (i.e., shorting TXP to GND) also has the same effect.

over 10 years ago

0 Praveen Aroul over 10 years ago

TI__Mastermind 49176 points

The AFE4400 / AFE4490 evaluation module is normally powered from the USB port.

Based on the USB specs, there is a limitation of 100 mA on the current draw from the USB port.

Shorting TP17 and TP25 (i.e.,shorting TXN to GND) draws around 320mA.

To verify the diagnostic feature under these conditions:

Install a 2 pin header on J5 (located right below the mini USB port).
Install a zero Ohm resistor (0803) on R114 (located on the bottom side of the EVM near J5)
Provide +5V on J5 Pin #1 from a power supply
Provide GND to J5 Pin #2
Now connect the USB cable to the USB port and start the PC GUI.
Short TP17 to TP25 and test the Diagnostic feature on the PC GUI.

Doing the above, the battery management device (BQ24032) on the EVM powers the EVM board from the external +5V. Assuming the external supply to provide the necessary current, creating this fault condition (i.e., shorting TXN or TXP to GND) will not cause the USB + GUI to crash and the diagnostic feature can be tested using the GUI.

0 Praveen Aroul over 10 years ago in reply to Praveen Aroul

TI__Mastermind 49176 points

How long does the diagnostics mode take to complete?

Can the AFE4490/AFE4400 Tx and Rx signal chains be used during the diagnostic mode?

0 Praveen Aroul over 10 years ago in reply to Praveen Aroul

TI__Mastermind 49176 points

For AFE4490, the diagnostic mode takes 8 ms.

For AFE4400, the diagnostic mode takes 16ms.

No, during the diagnostic mode, the AFE Tx and Rx signal chains cannot be used.

The device enters the diagnostic mode when bit2 of CONTROL0 register is set to '1'.

While the device is in diagnostic mode, if the bit2 of CONTROL0 register is set to '0', then the diagnostics is disabled.

While the device is in diagnostic mode, if the bit2 of CONTROL0 register is set to '1' again, then it will not do anything.

When the diagnostic is complete, the bit2 of CONTROL0 register is automatically reset.

Once the diagnostic mode is complete, the bit0 of CONTROL0 register must be set to '1' to enable SPI read.

And the status of the Diagnostics can be read from DIAG register (Addr: 0x30)

Refer to the AFE4490 / AFE4400 datasheet for more details about diagnostics.

0 Ali Bakhtiyari over 10 years ago in reply to Praveen Aroul

Prodigy 50 points

A question about diagnostic mode

Hello,

I use the AFE4400 EVB and also my board with has the an AFE4400.

EVB works perfectly in diagnostic mode.

In my board, the firmware only can recognize " the RxINP or RxINMcable shorted to GND" or " the TxOUTP or TxOUTMcable shorted to GND".

it can not recognize the PD OPEN or LED OPN.

Please kindly let me know what should I do.

Regards,

0 Amy Schnoor over 10 years ago in reply to Ali Bakhtiyari

TI__Mastermind 18275 points

Ali,

Would it be possible for you to send your schematic of your board?

0 Ali Bakhtiyari over 10 years ago in reply to Amy Schnoor

Prodigy 50 points

0 Ali Bakhtiyari over 10 years ago in reply to Amy Schnoor

Prodigy 50 points

0 Ali Bakhtiyari over 10 years ago in reply to Amy Schnoor

Prodigy 50 points

Hello Again and really thanks for your reply.

I hope this email finds you well.

Could you please kindly give me some information about the issue below?

Now, I can read the registers of AFE4400 via my firmware.

I know the value of registers 0x2A(LED2VAL) to 0x2F(LED1-ALED1VAL)

Now, I am looking for a Equation or formula which I can calculate the value of SO2 and heart rate.

Regards,

Ali

0 Praveen Aroul over 10 years ago in reply to Ali Bakhtiyari

TI__Mastermind 49176 points

Hello,

There is no simple equation or formula to calculate SpO2 and heart rate (HR).

For the HR estimation, you can feed the PPG signal through a band pass filter with 0.5 to 5 Hz cutoff frequencies to remove the unwanted signals and extract the signal bandwidth of interest and then implement a threshold crossing detector to calculate the pulse rate.

Please follow the article to understand the estimation of SpO2 using the PPG signals.

http://e2e.ti.com/support/applications/high_reliability/f/30/t/279797.aspx

Regards

Praveen.

0 Amy Schnoor over 10 years ago in reply to Praveen Aroul

TI__Mastermind 18275 points

Hello,

Could you tell me step by step what your diagnostic test procedure is and the register values during the PD open or LED open conditions?

Regards,

Amy

0 Ali Bakhtiyari over 10 years ago in reply to Amy Schnoor

Prodigy 50 points

Dear Amy,

thanks a lot for your consideration.

I solved the problem. :D

During diagnostic test procedure, If i disconnect or ground any signals, I will get the corresponding flag.

Now I am looking for algorithm or formula to calculate the HR and SPO2 . Please kindly let me know if you have any sources or documents,

Regards,

Ali

0 Amy Schnoor over 10 years ago in reply to Ali Bakhtiyari

TI__Mastermind 18275 points

Ali,

Happy to hear you solved the problem. As Praveen said above, there is no simple equation or formula to calculate SpO2 and heart rate (HR).

He did give a link that should be helpful.

0 Maulik Vaghela over 9 years ago in reply to Ali Bakhtiyari

Expert 2500 points

Hi,

I am facing same issue for afe4490 diagnostic.

When I am shorting red LED then corresponding flag is not being set.

Could you please suggest some solution ?

Thank you in advance. :)

0 Praveen Aroul over 9 years ago in reply to Maulik Vaghela

TI__Mastermind 49176 points

Hello Maulik,

I have responded to your question in the following E2E post:

http://e2e.ti.com/support/applications/high_reliability/f/30/p/358937/1260034.aspx#1260034

Regards

Praveen.

Data converters

Data converters forum

Diagnostic feature for AFE4490 / AFE4400