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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
78 of 808
NXP Semiconductors
UM10360
Chapter 8: LPC17xx Pin connect block
Function of PINMODE in open drain mode
Normally the value of PINMODE applies to a pin only when it is in the input mode. When a
pin is in the open drain mode, caused by a 1 in the corresponding bit of one of the
PINMODE_OD registers, the input mode still does not apply when the pin is outputting a
0. However, when the pin value is 1, PINMODE applies since this state turns off the pin’s
output driver. For example, this allows for the possibility of configuring a pin to be open
drain with an on-chip pullup. A pullup in this case which is only on when the pin is not
being pulled low by the pin’s own output.
5.
Register description
The Pin Control Module contains 11 registers as shown in
below.
Table 55.
Open Drain Pin Mode Select register Bits
PINMODE_OD0 to
PINMODE_OD4
Values
Function
Value after
Reset
0
Pin is in the normal (not open drain) mode.
00
1
Pin is in the open drain mode.
Table 56.
Pin Connect Block Register Map
Name
Description
Access
Reset
Value
Address
PINSEL0
Pin function select register 0.
R/W
0
0x4002 C000
PINSEL1
Pin function select register 1.
R/W
0
0x4002 C004
PINSEL2
Pin function select register 2.
R/W
0
0x4002 C008
PINSEL3
Pin function select register 3.
R/W
0
0x4002 C00C
PINSEL4
Pin function select register 4
R/W
0
0x4002 C010
PINSEL7
Pin function select register 7
R/W
0
0x4002 C01C
PINSEL8
Pin function select register 8
R/W
0
0x4002 C020
PINSEL9
Pin function select register 9
R/W
0
0x4002 C024
PINSEL10
Pin function select register 10
R/W
0
0x4002 C028
PINMODE0
Pin mode select register 0
R/W
0
0x4002 C040
PINMODE1
Pin mode select register 1
R/W
0
0x4002 C044
PINMODE2
Pin mode select register 2
R/W
0
0x4002 C048
PINMODE3
Pin mode select register 3.
R/W
0
0x4002 C04C
PINMODE4
Pin mode select register 4
R/W
0
0x4002 C050
PINMODE5
Pin mode select register 5
R/W
0
0x4002 C054
PINMODE6
Pin mode select register 6
R/W
0
0x4002 C058
PINMODE7
Pin mode select register 7
R/W
0
0x4002 C05C
PINMODE9
Pin mode select register 9
R/W
0
0x4002 C064
PINMODE_OD0
Open drain mode control register 0
R/W
0
0x4002 C068
PINMODE_OD1
Open drain mode control register 1
R/W
0
0x4002 C06C
PINMODE_OD2
Open drain mode control register 2
R/W
0
0x4002 C070