LPC54608 Ethernet MDIO CSR clock range for 180MHz

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LPC54608 Ethernet MDIO CSR clock range for 180MHz

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hlsamts
Contributor III

I am using the LPC54608 evaluation board OM13092 and want to get Ethernet running using a system core clock of 180 MHz. The examples of the SDK2.2 use only 48 MHz system core clock.

In the MAC_MDIO_ADDR register I have to select a CSR clock range (Bits 11:8). According to the user manual Rev2.0, I can set CSR values for clock ranges up to 150 MHz. How can I set a clock range for 180 MHz?

Best regards,

Holger

CSR.png

(Source: NXP UM10912 User Manual Rev. 2.0, Table 800)

P.S. The OM13092 uses a LAN8720 phy, which allows for a maximum MDC clock period of 400ns -> 2.5 MHz. If I would use the register value 1, I would get a clock of 180MHz / 62 = 2.9 MHz. Therefore I need the possibility to get a lower MDIO clock.

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andreschueer
Contributor II

Why is this change not integrated in the latest SDK 2.6. 

This issue was first delieverd to NXP from Holger Sachs end of 2017 and readressed by me May of 2019 and still this was not included in the SDK release from June 2019?

Will this never be integrated in the SDK?

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hlsamts
Contributor III

In the meantime I found out, that it is possible to use the value 0x4, which divides the core clock by 102. I found this value in the LPC43xx users manual (Rev 2.0, Table 606) and just gave it a try.

However:

Could anyone from NXP please give an official statement confirmation?

Please enahce your users manual with the next update.

Best regards,

Holger Sachs

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jeremyzhou
NXP TechSupport
NXP TechSupport

Hi Holger Sachs,

Thank you for your interest in NXP Semiconductor products and 
for the opportunity to serve you.
I'll contact with the AE team about this limitation.
Have a great day,

TIC

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andreschueer
Contributor II

That thread helped us as well,

but we need confirmation from NXP.

The newest user manual for LPC546xx, the UM10912 with version 2.2 from 29.10.2018, does not include the value 0x4 for the CR register as described above.

Also the fsl_enet - driver is therefore buggy as when a clock > 150Mhz is used, the default selected CR is 0.

In our example, we are running at 180Mhz and the MDC clock therefore is divided by 42 = 4.29 Mhz.

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hlsamts
Contributor III

I agree with you! It is definitely not acceptable that NXP does not care about this issue!

@NXP: Please do your homework.

By the way: jeremyzhou from NXP always promises that they will care about such issues. In my case, so far they cared about none.

441 Views
jeremyzhou
NXP TechSupport
NXP TechSupport

Hi Holger Sachs,

The below is the reply from the AE team, please check it.

Below is summary of the full CSR clock range table. The UM is incomplete and will be updated in next revision. This update will be also applied to LPC54(S)0xx series.

pastedImage_2.png


Have a great day,
TIC

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jeremyzhou
NXP TechSupport
NXP TechSupport

Hi Holger Sachs,

We both consider it should follow the same range rule as the below table shows, however, we need to contact the IP RD team for confirming.

pastedImage_1.png


Have a great day,
TIC

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