Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 17 replies
  • Subscribers 47 subscribers
  • Views 2240 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Clock specifications for AFE4400

Praveen Aroul
Mastermind 49756 points
Other Parts Discussed in Thread: AFE4400

Is it possible to run the AFE4400 on a buffered clock input rather than an external XTAL?

  • 0
    TI__Mastermind 49756 points

    Yes it is possible to connect a buffered clock input on the Xin pin of AFE4400. This requires that XTALDIS (bit 9) CONTROL2 Register (Reg 0x23h) is set to HIGH.

  • 0 in reply to Praveen Aroul
    TI__Mastermind 49756 points

    Why is 8 MHz the only supported frequency?

  • 0 in reply to Praveen Aroul
    TI__Mastermind 49756 points

    The AFE4400 has been characterized for 8MHz frequency only. Running at higher clock frequency will likely affect the ADC in the receive signal chain and impact the performance adversely.

  • 0 in reply to Praveen Aroul
    TI__Mastermind 49756 points

    Does TI have any recommendation for a small size 8MHz crystal?

  • 0 in reply to Praveen Aroul
    TI__Mastermind 49756 points

    For a small size crystal, our recommendation is the 8MHz Piezo Ceramic resonator crystal (CSTCE8M00G55-R0) which has the following dimensions (1.3 x 3.2 x 0.7mm)

  • 0
    Prodigy 130 points
    hellow Praveen Aroul,
    I have collected the data of the ppg, the date just like 87411, 89140,87769........
    How can I put these data into voltage value?
    Thank you very much.
  • 0 in reply to user4121441
    TI__Mastermind 49756 points
    Please refer to FAQ Question # 15 from the link below

    e2e.ti.com/.../369445
  • 0 in reply to Praveen Aroul
    Prodigy 130 points
    hellow, Praveen Aroul,
    you have told me how to get the voltage juest like below:
    ADC data (volts) = (ADC codes in two's complement format * Vref ) / 2^21
    where Vref = 1.2V
    But, I find the voltage by the AFE44X0SPO2VM GUI is about 1 v, I get the ADC results are about 20800, the result of 20800*1.2/2^21 is about 120mv,
    I don‘t know where I have made mistakes. Thank you very much.Best Regards
    --------------------------------------------------------------------------------
  • 0 in reply to Praveen Aroul
    Prodigy 130 points

    Hellow  ，

       I'm sorry to bother you. I met a problem of  data extraction.

       First of  all ,  I get  the signal from AFE44x0spo2EVM  GUI just like below:   

      The  configuration  just like below  :

    I save the  data by the GUI:

        

    By this picture ,we can find the data of (IR-IR AMBIEMT) is Seven digits ,by the formula :data*1.2/2^21,we can get the voltage is about 0.7v-0.8v, that right.


    This is the Register configuration  of 21h and 22h .

     

    In order to  separate  from  AFE44x0spo2EVM  GUI ,I need  to configurate Register of 21h and 22h to mcu software which offer by TI.  I configurate Register of 21h and 22h juest like below:


        However, I get the signal data of  (IR-IR AMBIEMT) and  (R-R AMBIEMT)are 6  digits!   by the formula :data*1.2/2^21,I can get the voltage is so small , that wrong. But I do not know where I have  done wrong. Configurating register of 21h and 22h to mcu software is right?

        sorry to bother you.  Looking forward to your answer, Thank you very much!

    Best regards.

                              XLL

  • 0 in reply to user4121441
    TI__Mastermind 49756 points
    Hello,

    After you have configured the AFE registers in the MCU, you could read back all the registers to verify whether the registers have been configured correctly.
  • 0 in reply to Praveen Aroul
    Prodigy 130 points
    I have configured the AFE registers in the MCU by macro definition,just like : #define LCDCNTRL_VAL (0x011428ul)
    because I only configured LED current and CF ,RF,STG2_GAI by AFE44x0spo2EVM GUI ,so I only change the 21h and 22h value in the MCU by macro definition,but I fail to get the data what I want.
    sorry to bother you.
  • 0
    Prodigy 130 points
    I run the AFE4400 on an external XTAL which is 8M
  • 0 in reply to user4121441
    TI__Mastermind 49756 points
    Do you read back the same values you have configured from the AFE registers?

    Is your board and test setup exactly similar to the AFE4400 EVM?
    Do you connect the transmissive finger clip pulseox sensor to your board?
    Do you see the sensor LEDs turn on?
    What values do you read on Red, IR, Red Ambient and IR Ambient channels?
  • 0 in reply to Praveen Aroul
    Prodigy 130 points

    Hellow  Praveen Aroul:

               My  testboard is similar to the AFE4400EVM, I have connected  the transmissive finger clip pulseox sensor to my board  and I can get the signal  by AFE44X0spo2EVM, then I want to configure AFE4400  by MCU software instead of  AFE44X0spo2EVM ,but I can get the signal is smaller than  the signal which I  got  by  AFE44X0spo2EVM. I configure AFE4400  by MCU software  according to  I configure AFE4400 by AFE44X0spo2EVM. So I think the reason is  that I  fail to configure AFE4400 by  MCU software.

          I find the example  code,the code definite the register just like below:

    if I  want to change the walve of 0x22 register bu MCU softwave, what are the steps?

    Thank you very much.

     

     

  • 0 in reply to user4121441
    TI__Mastermind 18285 points
    User,

    If you want to change the value of the registers without using our GUI, then you will need to program it by the MCU. You will need an IDE that supports the MCU you are using. I'm assuming it is the MSP430 as we used in our EVM.
  • 0 in reply to Praveen Aroul
    Prodigy 130 points

    Hello Praveen Aroul：

             I'm sorry to bother you. I set  the AFE44x0SPO2EVM  GUI  just  as below picture. I don't  know meaning of the 500hz..

            The 500hz  is sampling rate of the IR(or RED)? or  if I set 500hz,  then sampling rate of the IR(or RED) is  250?

    Thanks.

           XLL  2015.12.10

  • 0 in reply to user4121441
    TI__Mastermind 49756 points

    XLL,

    If PRF is set to 500hz, it is the sampling rate of the IR(or RED).

    Refer to the Section 8.3 in the AFE4400 datasheet for a more detailed understanding of the device and the timing engine.