DP83TG720S-Q1: The setting to 0x1834 (PMA_PMD_CONTROL Register) is not reflected.

Hello,

1. Since you are using USB-2-MDIO, try setting the register address to 0x1834 as if you are writing to it directly. If you have extended register set to yes, the software should do all indirect addressing for you.
2. DP83TG720 does not support 100Base-T1.

Regards,

Adrian Kam

1. I tried it, but the result did not change.

Also, I did it while observing the waveform using another device without using USB2MDIO, but the result was still as follows.
　(1) write 0x000D 0x0001
　(2) write 0x000E 0x1834
　(3) write 0x000D 0x4001
　(4) write 0x000E 0x0000
Register read for confirmation
　(5) write 0x000D 0x0001
　(6) write 0x000E 0x1834
　(7) write 0x000D 0x4001
　(8) read 0x000E 0xC001 ← Why isn't it 0x8000?

After all, is there any procedure to access this register?

2. Is 100base-T1 really not supported?
　I think it is supported for the following reasons.
　address = 0x1834: PMA_PMD_CONTROL Register
　Bit [3: 0]: cfg_type_selection
　Type: R / W
　4b0000 = 100BASE-T1
　4b0001 = 1000BASE-T1
　The register type of cfg_type_selection is specified as R / W.
　Therefore, if I set it to 4b0000, it would be 100BASE-T1

Hello,

1. Can you try the four step extended register access procedure again in USB-2-MDIO? This time, set the extended register setting in the software to "No" and see if it works this time.
2. Are you able to read/write to any of the basic registers (0x00 to x1F) or read/write to any of the other extended registers?
3. DP83TG720 does not support 100Base-T1. The option is in the datasheet because it is an IEEE standard register, but if you try to set it to 100Base-T1, the device will not work.

Regards,

Adrian Kam

Hello Adrian
I'm sorry I often forgot to say hello.

1.I set the software extension register setting to "NO"
　I set it up and tried it in a 4-step procedure.
　The result could not be written.

2. I tried to access the register below.
　Extended mode register: TEST_MODE_CONTROL Register (Address = 0x1904)

　I was able to read and write the results.
　The software extension register using USB2MDIO is set to "no".
　The following is the result.

Blank reading
　Register 000d is: 0001
　Register 000e is: 0904
　Register 000d is: 4001
　Register 000e is: 0000 ← Check normal_mode (Read operation)
TEST_mode1 setting
　Register 000D is: 0001
　Register 000E is: 0904
　Register 000D is: 4001
　Register 000E is: 2000 ← Set Test_mode1 (Write operation)
Check if it is set
　Register 000d is: 0001
　Register 000e is: 0904
　Register 000d is: 4001
　Register 000e is: 2000 ← Confirm that Test_mode1 is set. (Read operation)

Why can I read and write with 0x1904 but not with 0x1834?

3.I was able to understand. thanks you.

Hello,

I noticed a difference when you are accessing 0x1904 vs 0x1834. On step 2, when writing to register 0x000E first, can you try writing the value 0x0834 (instead of 0x1834) and see if you can successfully write to 0x1834? The rest of the steps should be the same. It seems the first four bits are not needed since it is set in the first step of writing to 0x000D.

Regards,

Adrian Kam

Hello,

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Regards,

Adrian Kam