88e3015 Marvell Semiconductor, Inc., 88e3015 Datasheet - Page 48

• Manufacturer Part Number: 88e3015
• Description: Integrated 10/100 Fast Ethernet Transceiver
• Manufacturer: Marvell Semiconductor, Inc.

Table 26:
2.12.3 Changing Auto Calibration Targets
The PHY runs the automatic calibration circuit with a 49 ohm impedance target by default after hardware reset.
Other impedance targets are available by changing the impedance target and restarting the auto calibration
through register writes.
To change the auto calibration targets, write to the following registers:
Write to register 29 = 0x000B
Write to register 30, bit 6:4 = ppp (write new PMOS Target value)
Write to register 30, bit 2:0 = nnn (write new NMOS Target value)
Write to register 29 = 0x000A
Write to register 30 = 0x8000 (Restarts the auto calibration with the new target)
Example: To set the approximate 54 ohm auto calibration target, write the following:
Reg29 = 0x000B
Reg30, bit 6:4 =
Reg29 = 0x000A
Reg30 = 0x8000
2.12.4 Manual Settings to The Calibration Registers
To use manual calibration, write to the following registers:
Write to register 29 = 0x000A
Write to register 30 = b'000P PPPP 011N NNNN -- adjusts PMOS strength
Doc. No. MV-S103657-00, Rev. C
Page 48
R e g
bi t
5
4:0
F u n c t i o n
PMOS/NMOS select
NMOS Value
Register 30 Page 10 - MAC Interface Calibration Definitions (Continued)
‘011’
and bit 2:0 =
88E3015/88E3018
Integrated 10/100 Fast Ethernet Transceiver
‘011’
Document Classification: Proprietary Information
S e t t in g d e s c r i p t io n
1 = PMOS value is written when LATCH is
0 = NMOS value is written when LATCH is
00000 = All fingers off
...
11111 = All fingers on
The automatic calibrated values are stored
here after calibration completes.
Once the LATCH bit is set to 1, the new cal-
ibration value is written. The automatic cali-
brated value is lost.
set to 1
set to 1
CONFIDENTIAL
M o d e
R/W
R/W
October 26, 2006, Advance
Copyright © 2006 Marvell
H W
R e s e t
0
Auto cal-
ibrated
value
S W
R e s et
Retain
Retain