Tool/software:
Hello,
I am currently working on integrating the DP83822 PHY with an STM32H735IGT3 microcontroller to establish Ethernet connectivity. I have configured the Ethernet interface, and when I connect the Ethernet cable, it is detected successfully, and the device appears on the PC.
However, while reading the PHY registers, I observe the following:
- The PHY registers are accessible, and their values can be read correctly.
- Despite this, the Link Up status (bit 2 in the Basic Mode Status Register [BMSR], address 0x0001) does not get set.
I have verified the hardware connections, PHY initialization sequence, and ensured the clock and power are stable for the DP83822. Below are the address value obtained when the read the following DP83822 PHY registers.
| Register Name | Register Address | Description | Value Read |
| DP83822_BCR | 0x0000U | //Basic Mode Control Register | 0x3100 |
| DP83822_BSR | 0x0001U | //Basic Mode Status Register | 0x786D |
| DP83822_PHYI1R | 0x0002U | //PHY Identifier Register #1 | 0x2000 |
| DP83822_PHYI2R | 0x0003U | //PHY Identifier Register #2 | 0xA240 |
| DP83822_ANAR | 0x0004U | //Auto-Negotiation Advertisement Register | 0x01E1 |
| DP83822_ANLPAR | 0x0005U | //Auto-Negotiation Link Partner Ability Register | 0xCDE1 |
| DP83822_ANER | 0x0006U | //Auto-Negotiation Expansion Register | 0x000F |
| DP83822_ANNPTR | 0x0007U | //Auto-Negotiation Next Page Register | 0x2001 |
| DP83822_ANLNPTR | 0x0008U | //Auto-Negotiation Link Partner Ability Next Pag | 0x4B9B |
| DP83822_CR1 | 0x0009U | //Control Register #1 | 0x0000 |
| DP83822_CR2 | 0x000AU | //Control Register #2 | 0x0100 |
| DP83822_CR3 | 0x000BU | //Control Register #3 | 0x1000 |
| DP83822_REGCR | 0x000DU | //Register Control Register | 0x0000 |
| DP83822_ADDAR | 0x000EU | //Data Register | 0x0000 |
| DP83822_FLDS | 0x000FU | // Fast Link Down Status Register | 0x0000 |
| DP83822_PHYSTS | 0x0010U | //PHY Status Register | 0x4015 |
| DP83822_PHYSCR | 0x0011U | //PHY Specific Control Register | 0x0108 |
| DP83822_RCSR | 0x0017U | //RMII and Status Register | 0x0065 |
| DP83822_PHYCR | 0x0019U | // PHY Control Register | 0x8C21 |
| DP83822_PHYRCR | 0x001FU | // PHY Reset Control Register | 0x0000 |
Could you please provide any guidance on what might be causing this issue? Are there any specific initialization steps, configuration registers, or debug methods recommended to troubleshoot the Link Up status in the DP83822 and establish data transmission.
Regards,
Srijan
