DP83826I: Some questions when transferring DP83822I to DP83826I

Xiaoying Lu

Part Number: DP83826I

Hi team,

My customer has some questions in DP83826 design.

Firstly, they are doing 100MHz EtherCAT in motor drive applications, and they want to know which mode should be selected, basic mode or enhanced mode?

Secondly, they have encountered some issue for the status of LED0/LED1. In EtherCAT applications, the ARM MCU needs a link signal and typically this signal is provided by LED0/LED1 of DP83826. The link signal should be ON/OFF instead of blink.

- If it is enhanced mode, the default function of Pin30 is LED0, but the default function of LED0 is link/active, which cannot meet their requirements. The default function of Pin 31 is CLKOUT, while theoretically LED1 can be set by STRAP6, but they don't know whether it is doable and how to set LED1 via STRAP6. Can you help advise?

- Or, if it is basic mode, the default function of Pin30 is the same with that of enhanced mode, so it cannot meet their requirements either. While for Pin31 in this mode, the default function is TX_ER. If they want to use this pin for LED1 to generate ON/OFF signal, they have to do some register modification, is that correct? And can you help advise how to do that? And how about the feasibility analysis compared with basic mode?

Please help answer the above questions and thanks in advance!

Regards,

Xiaoying

over 4 years ago

0 Lucas Wolter over 4 years ago

TI__Mastermind 28100 points

Hi Xiaoying,

This app note explains how to configure the DP83826 for EtherCAT applications: https://www.ti.com/lit/an/snla344a/snla344a.pdf?ts=1624901317753&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83826E

LED activity can be controlled through registers 0x25 and 0x460. What is your desired LED behavior? What functions should they monitor?

Yes, Pin 30 default function is the same in enhanced and basic modes. However if you refer to my above statement, LED0 function can be changed with those registers.

Refer to Table 9-11 on the DP83826 datasheet. If RX_ERR is strapped for mode 0, Pin 31 will act as CLKOUT. If strapped for mode 1, it'll act as LED1.

Thanks,

Lucas

All information in this correspondence and in any related correspondence is provided “AS IS” and “with all faults”, and it is subject to TI’s Important Notice (www.ti.com/.../important-notice.shtml).

0 Xiaoying Lu over 4 years ago in reply to Lucas Wolter

TI__Expert 4280 points

Hi Lucas,

Can you also advise which mode, basic mode or enhanced mode need be chosen in EtherCAT?

Regards,

Xiaoying

0 Lucas Wolter over 4 years ago in reply to Xiaoying Lu

TI__Mastermind 28100 points

Hi Xiaoying,

We're looking into your question and will provide feedback by tomorrow.

Thanks,

Lucas

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

0 Lucas Wolter over 4 years ago in reply to Lucas Wolter

TI__Mastermind 28100 points

Hi Xiaoying,

Enhanced mode should be chosen for EtherCAT.

Thanks,

Lucas

0 Xiaoying Lu over 4 years ago in reply to Lucas Wolter

TI__Expert 4280 points

Hi Lucas,

Can you help further advise why enhanced mode is a must for EtherCAT as seems that there is no clear definition in the datasheet? Is it because the different functions for the two modes? Thanks!

Regards,

Xiaoying

0 Lucas Wolter over 4 years ago in reply to Xiaoying Lu

TI__Mastermind 28100 points

Hi Xiaoying,

We're looking into your question and will get back to you by Tuesday.

Thanks,

Lucas

+1 Lucas Wolter over 4 years ago in reply to Lucas Wolter

TI__Mastermind 28100 points

Hi Xiaoying,

EtherCAT requires certain functions such as fast link-drop which are only available in enhanced mode. Therefore, enhanced mode is necessary for EtherCAT.

Thanks,

Lucas

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DP83826I: Some questions when transferring DP83822I to DP83826I