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TLK105L : LED doesn't blink

g.f.
Guru 15520 points
Other Parts Discussed in Thread: TLK105L, TLK105

Hi,

My customer are having trouble with TLK105L LED_LINK.

The LED_LINK pin is pullup with 2.2k, so that it is low active.

When LINK is ok, the LED will LINK. But when the transmitter or receiver is active, LED doesn't blink but it will link.

They are setting the register as follows:

Case1. <MLED is not routed to LED_LINK(17pin)>

(1)LED Control Register (LEDCR), address 0x0018, value = 0x0600

(2)PHY Control Register (PHYCR), address 0x0019, value = 0x8000

(3)Multi LED Control register (MLEDCR), address 0x0025, value = 0x0040

Case2.<MLED is routed to LED_LINK(17pin)>

(1)LED Control Register (LEDCR), address 0x0018, value = 0x0600

(2)PHY Control Register (PHYCR), address 0x0019, value = 0x8000

(3)Multi LED Control register (MLEDCR), address 0x0025, value = 0x0043

In either case, LED doesn't blink but it will link when the transmitter or receiver is active.

Are there any register need to be configured?

And are there any reason why LED doesn't blink?

best regards,

g.f.

  • 0
    TI__Mastermind 19780 points
    Hi g.f.,

    Is the receiver/transmitter on continuously during LED testing?

    If not, you may not be seeing the blinking due to low frequency setting. You may try other blink rates besides 2Hz. Try 5Hz or 10Hz. Configure the 5Hz rate with LEDCR register 0x0018 set to value 0x0400

    Best Regards,
  • 0 in reply to Rob Rodrigues
    Guru 15520 points
    Hi Rob,

    Thank you for the reply.
    I'm asking to the customer now.

    By the way, may I think that there is no other register configuration required?

    best regards,
    g.f.
  • 0 in reply to g.f.
    TI__Mastermind 19780 points
    g.f.

    For your application, yes, only registers 0x18, 0x19, 0x25 need to be manipulated. Register 0xA does have bit 4 related to the LED but since the LED is illuminating for LINK, then this bit doesn't matter.

    Regards,
  • 0 in reply to Rob Rodrigues
    TI__Mastermind 23675 points
    Hi g.f.,

    The TLK devices allow you to configure the LED to BLINK for activity. If you pull-down CRS (LED_CFG), this will configure the device to function for BLINK on activity and ON for LINK. The default strap for LED_CFG is Pull-UP, which will only have the LED ON for link and not blink.

    Kind regards,
    Ross
  • 0 in reply to Ross Pimentel
    Guru 15520 points
    Hi Rob and Ross,

    Thank you for the reply.

    Do you mean that CRS(LED_CFG) pin need to be Pull-Down for LED to blink?
    In datasheet page.28 , it said as follows:
    ////////////////////////////////////////////////////////////////////////////////////////////////////////
    LED Configuration: This option selects the operation mode of the LED LINK pin. Default
    is Mode 1. All modes are also configurable via register access. See PHY Control Register
    (PHYCR), Address 0x0019.
    ///////////////////////////////////////////////////////////////////////////////////////////////////////
    So, I thought that whether LED_CFG is Pull-down or not, it can configure from PHYCR register to blink the LED.
    Is this misunderstood?

    best regards,
    g.f.
  • 0 in reply to g.f.
    TI__Mastermind 19780 points

    Hi g.f.

    You can change the mode to blink the LED on activity by writing to PHYCR register 0x19 as you read in the datasheet.  Pulling down the CRS pin to set blink to default might help you troubleshoot the issue further.  That is why we suggested it.

    Best Regards,

  • 0 in reply to Rob Rodrigues
    Guru 15520 points
    Hi Rob,

    I have updates about the LED Blinking issue with TLK105L.

    Previously my customer was setting the TLK105L register as follows:
    (1)LED Control Register(LEDCR) = 0x0200
    (2)PHY Control Register(PHYCR) = 0x8000
    (3)Multi LED Control Register(MLEDCR) = 0x0040
    (4)Control register 2 (CR2) = 0x0016

    LED_LINK(pin 17) is controlling LED(MLED is not routed to either LED_LINK(pin17) or COL(pin29)).
    With this setting, LED didn't blink during communication.

    But when they changed "Control register 2 (CR2)" value to 0x0006,
    LED blinked during communication.
    (1)LED Control Register(LEDCR) = 0x0200
    (2)PHY Control Register(PHYCR) = 0x8000
    (3)Multi LED Control Register(MLEDCR) = 0x0040
    (4)Control register 2 (CR2) = 0x0006

    They changed the value of CR2 bit[4]. From TLK105 datasheet CR2 bit[4] description,
    " 1 = LED Link is ON only when link is established in 100B-TX Full Duplex mode"
    " 0 = LED Link is ON when link is established "

    From description of CR2 bit[4], I can't understand the reason
    why LED got available to blink by just changing the CR2 bit[4].

    Can you tell me the reason?

    best regards,
    g.f.