MDIO

Drive MDIO phy interface with a Chisel component. Test it with ksz8081rnb phy.

Wishbone interface

Wishbone slave is a simple 16bits data interface with 4 registers.

16bits addr	register name
0x0	status
0x1	control
0x2	readData
0x3	writeData

status

bit	15..8	7..1	0
name	version	void	busy

with:

• version in decimal without dot (1.0 -> 10)
• busy: set if frame is sending

control

bit	15	...	7..5	4..0
name	R	void	aphy	areg

with:

• R: read bit, must be set to emit read frame
• aphy: phy address number
• areg: register number

readData

bit	15 .. 0
name	readData

writeData

bit	15 .. 0
name	writeData

Typical use

Send write data frame

To send data frame on the mdio bus follow this step :

• monitor the busy bit in status register, if the bit is low go to following step.
• Write phy address and reg address in control register
• Write data in writeData register. The wishbone write will trigger the data mdio write frame.
• monitor the busy bit, once busy bit is low, write data frame has been sent.

Send read data frame

• monitor the busy bit in status register, if the bit is low go to following step.
• Write phy address, reg address and read bit 'R'. Writing the 'R' bit will trigger the read mdio frame
• monitor the busy bit, once busy bit is low, read data frame is terminated.
• read readData register to get the data read.

tests

To launch test use the makefile with commands:

$ make testall