• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 33 subscribers
  • Views 1155 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

DP83822I: LED_0 isn't blink when TX/RX is active.

Shinichi Inoue
Guru 21676 points
Part Number: DP83822I

Dear Specialists,

MY customer is evaluating DP83822I and encountering a problem.

I would be grateful if you could advise.

---

According to the datasheet, When LED_ 0 is using for BLINK for TX/RX Activity, should be use MODE1 or 2. 

I choose MODE1(1.96ohm pulldown) at LED_0pin, but it output H stable instead of blinking when ethernet had established.

Related resister data is listed below.

Table 40. 0x0019 PHY Control Register (PHYCR) BIT5 LED Configuration is 0

Table 46. 0x0025 Multi-LED Control Register (MLEDCR) BIT6:3 MLED Configuration (COL Pin) is set 0000(default).

0x0019 Bit 5 is strapped pin, so it doesn't need to set the resister.

0x0025 Bit6:3 are not strapped, are these need to set the resister?

Are there any resisters to set?

Does this means it is impossible to set "BLINK with TX / RX communication" only by Strap pin connection?

---

I appreciate your great help in advance.

Best regards,

Shinichi

  • 0
    TI__Mastermind 18425 points
    Hello Shinichi,

    Did you connect the pull down resistor on LED_0 pin or CRS pin? Also the pull down value should be 1.96kohm and not 1.96ohm. This might just be a typo when you were posting the question but I just want to be sure.

    Led_0 functionality is controlled by 'LED_CFG' bit. However, LED_CFG is connected to CRS pin strap. So effectively, strap on CRS pin will control functionality of LED_0 pin. Please note that in order for LED_0 to function properly, a parallel pull resistor is still required.

    So in summary, you will need a 1.96kohm pull down resistor on CRS pin to program LED_0 in blinking mode. And you will also need 1.96kohm pull up resistor in parallel to LED on LED_0 pin for proper function of LED. LED_0 is also a strap pin, so pull up resistor will enable autonegotiation.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Guru 21676 points
    Hi Aniruddha,

    Thank you for your reply.

    Fifstly, It's a typo of 1.96ohm, I'm sorry about that.

    I understand LED_0 needs a parallel resistor and CRS needs pulldown.

    I'll share these information with the customer.

    I appreciate your great help.

    If the customer has an additional question, I cousult you again.

    Best regards,
    Shinichi
  • 0 in reply to Shinichi Inoue
    Guru 21676 points

    Hi Aniruddha,

    I received an additional question from the customer.

    I would be grateful if you could advise.

    ---

    If the target register (LED_CFG) is rewritten every time by software at startup, can it change the preset value with the hard pin strap and use it?

    ---

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 18425 points
    Hello Shinichi,

    LED_CFG is controlled through strap on CRS pin and via register 0x19 bit 5. If customer is using software to write to register 0x19, then after every power-up/reset the PHY will loose the software configuration and return back to default value. If customer do not wish to use software configuration they should use strap on CRS pin.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Guru 21676 points

    Hi Aniruddha,

    Thank you for your reply.

    Could you please advise one more thing.

    Firstly setting the strap pin, and then writing to register 0x19 using software, which setting is effective?

    I think register data has priority, correct?

    I appreciate your great help.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 18425 points
    Hi Shinchi,

    Immediately after power up, the strap settings will come into effect. After software configuration, the software settings will be used and the strap settings will be overwritten.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Guru 21676 points

    Hi Aniruddha,

    Thank you for your reply.

    I understand the software setting can overwrite the strap setting.

    I'll share this information with the customer.

    Best regards,

    Shinichi