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DP83826I: Using SMI to set RMII mode

Johan Nylund
Prodigy 250 points
Part Number: DP83826I

Hi

We have a new design where we use DP83826I. We need to use RMII to MAC but the strapping makes us enter MII mode (basic mode and strap10/3/4 all default pulled down to 0)

I thought that all strapping configurations could be changed by SMI register writes after power up. But I am not sure anymore.

First We tried to white SOR2 register but I guess it is Read Only since We can not change the value 0x87. 


Is it possible to change from MII to RMII mode after power up with SMI register writes?
I have seen on other phy’s like DP83822 that RCSR register 0x17 bit 5 can be used to charge to RMII mode but on DP83826 this bit is stated as reserved.

Also We have made a hardware patch on our board so that strap4 (COL pin 28) is pulled High. Then We enter RMII mode on power up and everything works just fine.

But to avoid a hardware spin on the board and for understanding of the possibilities of configuration with SMI register writes We would like a description on hon to charge to RMII mode using SMI writes after power up, or some kind of explaination of why it can not be done?

Regards

/Johan

  • 0
    TI__Genius 9920 points

    Hi Johan,

    Yes you should be able to change modes through register writes. Have you confirmed you are using extended register sets when you are writing?

    Can you please share the register dump?

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 250 points

    Hi Cecilia

    Thanks for your reply.

    Yes we are using extended register access for the registers above 0x1F (REGCR and ADDAR reegisters used for access)

    What would the correct register writes be to change to RMII (after powered up in MII by strapping)? 

    We can not understand that from the datasheet register specifications (SOR2 tegister seems to be read only and RCSR bit 5 is reserved)

    Yes I can provide an register dump.

    Which registers do you want to view? all?

    Fullscreen PHY_register_dump_hw_strapped_to_RMII.txt Download 
    00> [   126.962] DumpPHYRegisters | --- Beginning PHY register dump ---
00> [   126.962] DumpPHYRegisters | PHY REG# 000 = 1000
00> [   126.972] DumpPHYRegisters | PHY REG# 001 = 786D
00> [   126.982] DumpPHYRegisters | PHY REG# 002 = 2000
00> [   126.992] DumpPHYRegisters | PHY REG# 003 = A110
00> [   127.002] DumpPHYRegisters | PHY REG# 004 = 01E1
00> [   127.012] DumpPHYRegisters | PHY REG# 005 = 45E1
00> [   127.022] DumpPHYRegisters | PHY REG# 006 = 0005
00> [   127.032] DumpPHYRegisters | PHY REG# 007 = 2001
00> [   127.042] DumpPHYRegisters | PHY REG# 008 = 0000
00> [   127.052] DumpPHYRegisters | PHY REG# 009 = 0000
00> [   127.062] DumpPHYRegisters | PHY REG# 00A = 0100
00> [   127.072] DumpPHYRegisters | PHY REG# 00B = 0000
00> [   127.082] DumpPHYRegisters | PHY REG# 00C = 0000
00> [   127.092] DumpPHYRegisters | PHY REG# 00D = 401F
00> [   127.102] DumpPHYRegisters | PHY REG# 00E = 0000
00> [   127.112] DumpPHYRegisters | PHY REG# 00F = 0000
00> [   127.122] DumpPHYRegisters | PHY REG# 010 = 4615
00> [   127.132] DumpPHYRegisters | PHY REG# 011 = 010B
00> [   127.142] DumpPHYRegisters | PHY REG# 012 = 0000
00> [   127.152] DumpPHYRegisters | PHY REG# 013 = 0000
00> [   127.162] DumpPHYRegisters | PHY REG# 014 = 0000
00> [   127.172] DumpPHYRegisters | PHY REG# 015 = 0000
00> [   127.182] DumpPHYRegisters | PHY REG# 016 = 0100
00> [   127.192] DumpPHYRegisters | PHY REG# 017 = 0065
00> [   127.202] DumpPHYRegisters | PHY REG# 018 = 0400
00> [   127.212] DumpPHYRegisters | PHY REG# 019 = 8C01
00> [   127.222] DumpPHYRegisters | PHY REG# 01A = 0000
00> [   127.232] DumpPHYRegisters | PHY REG# 01B = 007D
00> [   127.242] DumpPHYRegisters | PHY REG# 01C = 05EE
00> [   127.252] DumpPHYRegisters | PHY REG# 01D = 0000
00> [   127.262] DumpPHYRegisters | PHY REG# 01E = 0102
00> [   127.272] DumpPHYRegisters | PHY REG# 01F = 0000
00> [   127.282] DumpPHYRegisters | PHY REG# 025 = 0041
00> [   127.292] DumpPHYRegisters | PHY REG# 027 = 0000
00> [   127.302] DumpPHYRegisters | PHY REG# 02A = 7998
00> [   127.312] DumpPHYRegisters | PHY REG# 117 = 8147
00> [   127.322] DumpPHYRegisters | PHY REG# 131 = 228A
00> [   127.332] DumpPHYRegisters | PHY REG# 170 = 0C12
00> [   127.342] DumpPHYRegisters | PHY REG# 171 = C850
00> [   127.352] DumpPHYRegisters | PHY REG# 172 = 0000
00> [   127.362] DumpPHYRegisters | PHY REG# 173 = 0D04
00> [   127.372] DumpPHYRegisters | PHY REG# 174 = 0000
00> [   127.382] DumpPHYRegisters | PHY REG# 175 = 1004
00> [   127.392] DumpPHYRegisters | PHY REG# 176 = 0005
00> [   127.402] DumpPHYRegisters | PHY REG# 177 = 1E00
00> [   127.412] DumpPHYRegisters | PHY REG# 178 = 0002
00> [   127.422] DumpPHYRegisters | PHY REG# 180 = 0000
00> [   127.432] DumpPHYRegisters | PHY REG# 181 = 0000
00> [   127.442] DumpPHYRegisters | PHY REG# 182 = 0000
00> [   127.452] DumpPHYRegisters | PHY REG# 183 = 0000
00> [   127.462] DumpPHYRegisters | PHY REG# 184 = 0000
00> [   127.472] DumpPHYRegisters | PHY REG# 185 = 0000
00> [   127.482] DumpPHYRegisters | PHY REG# 186 = 0000
00> [   127.492] DumpPHYRegisters | PHY REG# 187 = 0000
00> [   127.502] DumpPHYRegisters | PHY REG# 188 = 0000
00> [   127.512] DumpPHYRegisters | PHY REG# 189 = 0000
00> [   127.522] DumpPHYRegisters | PHY REG# 18A = 0000
00> [   127.532] DumpPHYRegisters | PHY REG# 302 = 0000
00> [   127.542] DumpPHYRegisters | PHY REG# 303 = 0008
00> [   127.552] DumpPHYRegisters | PHY REG# 304 = 000D
00> [   127.562] DumpPHYRegisters | PHY REG# 305 = 0008
00> [   127.572] DumpPHYRegisters | PHY REG# 306 = 0008
00> [   127.582] DumpPHYRegisters | PHY REG# 308 = 0980
00> [   127.592] DumpPHYRegisters | PHY REG# 30B = 3C00
00> [   127.602] DumpPHYRegisters | PHY REG# 30C = 0410
00> [   127.612] DumpPHYRegisters | PHY REG# 30E = 8400
00> [   127.622] DumpPHYRegisters | PHY REG# 404 = 0080
00> [   127.632] DumpPHYRegisters | PHY REG# 40D = 0008
00> [   127.642] DumpPHYRegisters | PHY REG# 456 = 0008
00> [   127.652] DumpPHYRegisters | PHY REG# 459 = 0000
00> [   127.662] DumpPHYRegisters | PHY REG# 45A = 0000
00> [   127.672] DumpPHYRegisters | PHY REG# 460 = 0565
00> [   127.682] DumpPHYRegisters | PHY REG# 461 = 0010
00> [   127.692] DumpPHYRegisters | PHY REG# 467 = 0097
00> [   127.702] DumpPHYRegisters | PHY REG# 468 = 0097
00> [   127.712] DumpPHYRegisters | PHY REG# 469 = 0000
00> [   127.722] DumpPHYRegisters | PHY REG# 4A0 = 1000
00> [   127.732] DumpPHYRegisters | PHY REG# 4A1 = 0000
00> [   127.742] DumpPHYRegisters | PHY REG# 4A2 = 0000
00> [   127.752] DumpPHYRegisters | PHY REG# 4A3 = 0000
00> [   127.762] DumpPHYRegisters | PHY REG# 4A4 = 0000
00> [   127.772] DumpPHYRegisters | PHY REG# 4A5 = 0000
00> [   127.782] DumpPHYRegisters | PHY REG# 4A6 = 0000
00> [   127.792] DumpPHYRegisters | PHY REG# 4A7 = 0000
    Fullscreen PHY_register_dump_MII.txt Download 
    00> [     3.618] DumpPHYRegisters | PHY REG# 000 = 1000
00> [     3.628] DumpPHYRegisters | PHY REG# 001 = 786D
00> [     3.638] DumpPHYRegisters | PHY REG# 002 = 2000
00> [     3.648] DumpPHYRegisters | PHY REG# 003 = A110
00> [     3.658] DumpPHYRegisters | PHY REG# 004 = 01E1
00> [     3.668] DumpPHYRegisters | PHY REG# 005 = 45E1
00> [     3.678] DumpPHYRegisters | PHY REG# 006 = 0007
00> [     3.688] DumpPHYRegisters | PHY REG# 007 = 2001
00> [     3.698] DumpPHYRegisters | PHY REG# 008 = 0000
00> [     3.708] DumpPHYRegisters | PHY REG# 009 = 0000
00> [     3.718] DumpPHYRegisters | PHY REG# 00A = 0100
00> [     3.728] DumpPHYRegisters | PHY REG# 00B = 0000
00> [     3.738] DumpPHYRegisters | PHY REG# 00C = 0000
00> [     3.748] DumpPHYRegisters | PHY REG# 00D = 0000
00> [     3.758] DumpPHYRegisters | PHY REG# 00E = 0000
00> [     3.768] DumpPHYRegisters | PHY REG# 00F = 0000
00> [     3.778] DumpPHYRegisters | PHY REG# 010 = 4615
00> [     3.788] DumpPHYRegisters | PHY REG# 011 = 010B
00> [     3.798] DumpPHYRegisters | PHY REG# 012 = 6400
00> [     3.808] DumpPHYRegisters | PHY REG# 013 = 2800
00> [     3.818] DumpPHYRegisters | PHY REG# 014 = 0000
00> [     3.828] DumpPHYRegisters | PHY REG# 015 = 0000
00> [     3.838] DumpPHYRegisters | PHY REG# 016 = 0100
00> [     3.848] DumpPHYRegisters | PHY REG# 017 = 0049
00> [     3.858] DumpPHYRegisters | PHY REG# 018 = 0400
00> [     3.868] DumpPHYRegisters | PHY REG# 019 = 8C01
00> [     3.878] DumpPHYRegisters | PHY REG# 01A = 0000
00> [     3.888] DumpPHYRegisters | PHY REG# 01B = 007D
00> [     3.898] DumpPHYRegisters | PHY REG# 01C = 05EE
00> [     3.908] DumpPHYRegisters | PHY REG# 01D = 0000
00> [     3.918] DumpPHYRegisters | PHY REG# 01E = 0102
00> [     3.928] DumpPHYRegisters | PHY REG# 01F = 0000
00> [     3.938] DumpPHYRegisters | PHY REG# 025 = 0041
00> [     3.948] DumpPHYRegisters | PHY REG# 027 = 0000
00> [     3.958] DumpPHYRegisters | PHY REG# 02A = 7998
00> [     3.968] DumpPHYRegisters | PHY REG# 117 = 8147
00> [     3.978] DumpPHYRegisters | PHY REG# 131 = 228A
00> [     3.988] DumpPHYRegisters | PHY REG# 170 = 0C12
00> [     3.998] DumpPHYRegisters | PHY REG# 171 = C850
00> [     4.008] DumpPHYRegisters | PHY REG# 172 = 0000
00> [     4.018] DumpPHYRegisters | PHY REG# 173 = 0D04
00> [     4.028] DumpPHYRegisters | PHY REG# 174 = 0000
00> [     4.038] DumpPHYRegisters | PHY REG# 175 = 1004
00> [     4.048] DumpPHYRegisters | PHY REG# 176 = 0005
00> [     4.058] DumpPHYRegisters | PHY REG# 177 = 1E00
00> [     4.068] DumpPHYRegisters | PHY REG# 178 = 0002
00> [     4.078] DumpPHYRegisters | PHY REG# 180 = 0000
00> [     4.088] DumpPHYRegisters | PHY REG# 181 = 0000
00> [     4.098] DumpPHYRegisters | PHY REG# 182 = 0000
00> [     4.108] DumpPHYRegisters | PHY REG# 183 = 0000
00> [     4.118] DumpPHYRegisters | PHY REG# 184 = 0000
00> [     4.128] DumpPHYRegisters | PHY REG# 185 = 0000
00> [     4.138] DumpPHYRegisters | PHY REG# 186 = 0000
00> [     4.148] DumpPHYRegisters | PHY REG# 187 = 0000
00> [     4.158] DumpPHYRegisters | PHY REG# 188 = 0000
00> [     4.168] DumpPHYRegisters | PHY REG# 189 = 0000
00> [     4.178] DumpPHYRegisters | PHY REG# 18A = 0000
00> [     4.188] DumpPHYRegisters | PHY REG# 302 = 0000
00> [     4.198] DumpPHYRegisters | PHY REG# 303 = 0008
00> [     4.208] DumpPHYRegisters | PHY REG# 304 = 000D
00> [     4.218] DumpPHYRegisters | PHY REG# 305 = 000E
00> [     4.228] DumpPHYRegisters | PHY REG# 306 = 000E
00> [     4.238] DumpPHYRegisters | PHY REG# 308 = 0980
00> [     4.248] DumpPHYRegisters | PHY REG# 30B = 3C00
00> [     4.258] DumpPHYRegisters | PHY REG# 30C = 0410
00> [     4.268] DumpPHYRegisters | PHY REG# 30E = 8400
00> [     4.278] DumpPHYRegisters | PHY REG# 404 = 0080
00> [     4.288] DumpPHYRegisters | PHY REG# 40D = 0008
00> [     4.298] DumpPHYRegisters | PHY REG# 456 = 0008
00> [     4.308] DumpPHYRegisters | PHY REG# 459 = 0000
00> [     4.318] DumpPHYRegisters | PHY REG# 45A = 0000
00> [     4.328] DumpPHYRegisters | PHY REG# 460 = 0565
00> [     4.338] DumpPHYRegisters | PHY REG# 461 = 0010
00> [     4.348] DumpPHYRegisters | PHY REG# 467 = 0087
00> [     4.358] DumpPHYRegisters | PHY REG# 468 = 0087
00> [     4.368] DumpPHYRegisters | PHY REG# 469 = 0000
00> [     4.378] DumpPHYRegisters | PHY REG# 4A0 = 1000
00> [     4.388] DumpPHYRegisters | PHY REG# 4A1 = 0000
00> [     4.398] DumpPHYRegisters | PHY REG# 4A2 = 0000
00> [     4.408] DumpPHYRegisters | PHY REG# 4A3 = 0000
00> [     4.418] DumpPHYRegisters | PHY REG# 4A4 = 0000
00> [     4.428] DumpPHYRegisters | PHY REG# 4A5 = 0000
00> [     4.438] DumpPHYRegisters | PHY REG# 4A6 = 0000
00> [     4.448] DumpPHYRegisters | PHY REG# 4A7 = 0000

    Regards

    /Johan

  • 0 in reply to Johan Nylund
    TI__Genius 9920 points

    Hi Johan,

    For RMII Strap txt:

    Reg 0x468= 0x0097 , bit 4 = 1, RMII mode

    For MII Strap txt:

    Reg 0x468 = 0x0087, bit 4 = 0, MII mode

    It looks like your strapping correctly. Please let me know if you need more clarity from this. 

  • 0 in reply to Cecilia Reyes
    Prodigy 250 points

    Hi Cecilia

    Yes we have no issue with setting the phy in RMII mode with a hardware patch. The strapping setting RMII on our board is not a mounting option it is change that will cause a new pcb spin because it is to complicated to handle in volume.

    The problem is that we can not write SOR2 register (0x468). My understanding is that it is  read only???  But I might be wrong.  Is your opinion that we should be able to write 0x468 bit 4?? In that case we are doing something wrong since we can not change the SOR2 register when we try to write it (using extended register access).                

    So what we need support with is instructions on how to set RMII mode through SMI register writes when we have powered up with the default strapping so that we enter MII mode.

    /Johan

  • 0 in reply to Johan Nylund
    TI__Genius 9920 points

    Hi Johan,

    That is correct SOR2 is read only.

    To manually R/W register to RMII or MII mode you will configure bit 5 of reg 0x17. Currently the register is labeled as reserved which could be a datasheet typo.

    Bit 5 outlines as 1 = RMII mode and 0 = MII mode which looks to be configuring as expected as well. This should allow you to read and write properly. 

    Let me know if that works for you.

    Thanks,

    Cecilia

  • 0 in reply to Cecilia Reyes
    Prodigy 250 points

    Hi Cecilia

    We have tested this and it works fine.

    Thanks for the support and clarifying the typo in the datasheet.

    Regards

    /Johan