TLK110 Function of Collison LED (LED Mode 2) with a full duplex link

Ueli,

Could you provide some basic details of your test platform?  Specifically, are you using the TLK110CUSEVM board or a board of your design or some other platform?  Do you have the ability to read and write the registers during your testing?

Patrick

Ueli seems to have forgotten to reply.

So let me continue...

It is a board of our own design.

We connect the tlk110 to a Freescale MCF5235

Yes we are able to read and write registers during testing.

I know that it is connected full duplex because our switches tell us so and so does the TLK110 itself.

We can't have collisions because we have full duplex so what is this LED telling us?

Best wishes,

Ahlan

A little bit more information.

We are trying to run in LED mode 3 (not 2 as stated in the original question).

In this mode Led_Link is on for a good link and blinks for activity.

This it does so we must be either in mode 2 or mode 3.

When I read PHYCR i get a value of 0xA211which doesn't match the documentation. (Revision June 2013, page 70) in which bit 11 is supposed to be MII link status. As we have 100 FD this shoud be set whereas for us it appears to be bit 9 which is documented as reserved. Bits 5 and 6 indicate the mode which according to the table indicate we are in mode 1 which we know we aren't. We know because the activity LED blinks on activity that we are in either mode 2 or 3. As mode 2 =0 by guess is that we are in mode 3 (which is what we want) and that the table has bits 5 and 6 swapped.

I have tried setting PHYCR bits 5 and 6 the other way around and we then enter mode 1 so I am confident that we are in mode 3. In which case Led_Act should be on to indicate FD. It shouldn't blink. either we have FD or we don't. However it blinks. But only when there is a lot of activity - ie it isn't indicating activity per se.

Has anyone any idea what this LED is telling us?

Best wishes

Ahlan

Could you provide a complete dump of the registers?  We would want to see registers 0x00 through 0x1F on register page 0x0.  Some registers latch their values and need to be read twice so please make sure that the registers are read twice and both reads are reported.  We would want to see these register reads for a device when the described LED functionality occurs.

Could you post the schematic of the board?  It would probably be worthwhile to review the schematic as well to confirm the connections. 

Patrick

Dear Patrick

Here is the register dump in response to the link-up interrupt.

Ueli should post the schematic ASAP.

1st read

BMCR = 0x3100
BMSR = 0x786D
PHYIDR1 = 0x2000
PHYIDR2 = 0xA211
ANAR = 0x01E1
ANLPAR = 45E1
ANER = 0x0005
ANNPTR = 0x2001
ALNNPTR = 0x0000
SWSCR1 = 0xF801
SWSCR2 = 0x0104
SWSCR3 = 0x0000
Reserved1 = 0x0000
REGCR = 0x0000
ADDR = 0x0000
Reserved2 = 0x0000
PHYSTS = 0x0615
PHYSCR = 0x010B
MISR1 = 0x0020
MISR2 = 0x2000
FCSCR = 0x0000
RECR = 0x0000
BISCR = 0x0100
RBR = 0x0009
LEDCR = 0x0424
PHYCR = 0x8801
BT10SCR = 0x0000
BICSR1 = 0x007D
BICSR2 = 0x05EE
Reserved3 = 0x0000
CDCR = 0x0102
PHYRCR = 0x0000

2nd read

BMCR = 0x3100
BMSR = 0x786D
PHYIDR1 = 0x2000
PHYIDR2 = 0xA211
ANAR = 0x01E1
ANLPAR = 45E1
ANER = 0x0005
ANNPTR = 0x2001
ALNNPTR = 0x0000
SWSCR1 = 0xF801
SWSCR2 = 0x0104
SWSCR3 = 0x0000
Reserved1 = 0x0000
REGCR = 0x0000
ADDR = 0x0000
Reserved2 = 0x0000
PHYSTS = 0x0615
PHYSCR = 0x010B
MISR1 = 0x0020
MISR2 = 0x0000
FCSCR = 0x0000
RECR = 0x0000
BISCR = 0x0100
RBR = 0x0001
LEDCR = 0x0424
PHYCR = 0x8801
BT10SCR = 0x0000
BICSR1 = 0x007D
BICSR2 = 0x05EE
Reserved3 = 0x0000
CDCR = 0x0102
PHYRCR = 0x0000

Note LEDCR = 0x0424 because we set the yellow speed light ourselves to indicate 100FD
because  LED_ACT does not show FD/HD

Ahlan

Hi Ahlan,

1. the status of the PHY (with regards to link) is read through register PHYSTS reg 0x10. your PHY register 0x10 reads 0x0615 --> this translates to
   1. link established
   2. speed 100
   3. full duplex
   4. autoneg complete
2. reg PHYCR is reg 0x19 both readings for this register are  PHYCR = 0x8801 --> bit 11 is MI_link not MII link and it is 1 on both your readings (you mention reading 0xA211(h) but this is PHYIDR2) meaning Link Status: 1 = 100BT Full-duplex Link is active and it was established using Auto-Negotiation.
3. PHYCR = 0x8801 -->  bits 6:5 are "00" --> this is mode 2. so for this mode you should see:
   1. led link: blink on activity or on for link but no activity
   2. led speed: on
   3. led act: on 

Thanks,

Aviad

Dear Aviad,

Ok I seem to have misread PHYCR - we seem to be in mode 2.

Which according to my documentation means that LED_ACT is on for collision and off for no-collision.

However we have full duplex so how can we have collisions?

The FEC and theswitch to which we are connect both report (unsurprisingly) no collisions.

LED_ACT seems to blink according to traffic load. If there is little traffic it is off, light load it blinks, heavy load it is full on. The original question remains therefore what is this LED telling us?

Best wishes

Ahlan

Dear Patrik, Aviad and Ahlan

Below i have posted the schematic details of the phy and related parts.
As Ahlan has written, the phy is connected to a Freescale MCF5235 processor.

Thank you, for supporting us.

Ueli

8103.Ausschnitt Ethernet Schema.pdf

Dear Aviad,

Thank you for supplying us with the answer.

In Mode 2 the Act_Led shows when receiving and transmitting occur simultaneously. Ie would cause a collision if half duplex.

I suggest that someone at Texas update the TLK110 manual to document this.

Many thanks,

Ahlan

Hi Ahlan,

Apreciate your comment !

we will edit the next DS version to better explain the behaviour of led_act.

Thanks !

Aviad