User Manual

AT75C220
47
MAC PHY Maintenance Register
Register Name: ETH_MAN
Access Type: Read/write
Reset Value: 0x0
Writing to this register starts the shift register that controls the serial connection to the PHY. On each shift cycle the MDIO
pin becomes equal to the MSB of the shift register and LSB of the shift register becomes equal to the value of the MDIO
pin. When the shifting is complete an interrupt is generated and the IDLE field is set in the Network Status register.
When read will give current shifted value.
• DATA
For a write operation this is written with the data to be written to the PHY. After a read operation this contains the data
read from the PHY.
• CODE
Must be written to 10. Will read as written.
• REGA
Register address. Specifies the register in the PHY to access.
• PHYA
PHY address. Normally will be 0.
• RW
Read/write Operation. 10 is read. 01 is write. Any other value is an invalid PHY management frame.
• HIGH
Must be written with 1 to make a valid PHY management frame.
• LOW
Must be written with 0 to make a valid PHY management frame.
31 30 29 28 27 26 25 24
LOW HIGH RW PHYA
23 22 21 20 19 18 17 16
PHYA REGA CODE
15 14 13 12 11 10 9 8
DATA
76543210
DATA