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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
98 of 808
NXP Semiconductors
UM10360
Chapter 9: LPC17xx General Purpose Input/Output (GPIO)
5.4 GPIO port Pin value register FIOxPIN (FIO0PIN to FIO7PIN- 0x2009
C014 to 0x2009 C094)
This register provides the value of port pins that are configured to perform only digital
functions. The register will give the logic value of the pin regardless of whether the pin is
configured for input or output, or as GPIO or an alternate digital function. As an example,
a particular port pin may have GPIO input, GPIO output, UART receive, and PWM output
as selectable functions. Any configuration of that pin will allow its current logic state to be
read from the corresponding FIOxPIN register.
If a pin has an analog function as one of its options, the pin state cannot be read if the
analog configuration is selected. Selecting the pin as an A/D input disconnects the digital
features of the pin. In that case, the pin value read in the FIOxPIN register is not valid.
Writing to the FIOxPIN register stores the value in the port output register, bypassing the
need to use both the FIOxSET and FIOxCLR registers to obtain the entire written value.
This feature should be used carefully in an application since it affects the entire port.
Access to a port pin via the FIOxPIN register is conditioned by the corresponding bit of
the FIOxMASK register (see
).
Only pins masked with zeros in the Mask register (see
) will be correlated to
the current content of the Fast GPIO port pin value register.
FIOxCLR3
Fast GPIO Port x output
Clear register 3. Bit 0 in
FIOxCLR3 register
corresponds to pin Px.24 …
bit 7 to pin Px.31.
8 (byte)
WO
0x00
FIO0CLR3 - 0x2009 C01F
FIO1CLR3 - 0x2009 C03F
FIO2CLR3 - 0x2009 C05F
FIO3CLR3 - 0x2009 C07F
FIO4CLR3 - 0x2009 C09F
FIOxCLRL
Fast GPIO Port x output
Clear Lower half-word
register. Bit 0 in FIOxCLRL
register corresponds to pin
Px.0 … bit 15 to pin Px.15.
16 (half-word)
WO
0x0000 FIO0CLRL - 0x2009 C01C
FIO1CLRL - 0x2009 C03C
FIO2CLRL - 0x2009 C05C
FIO3CLRL - 0x2009 C07C
FIO4CLRL - 0x2009 C09C
FIOxCLRU Fast GPIO Port x output
Clear Upper half-word
register. Bit 0 in FIOxCLRU
register corresponds to pin
Px.16 … bit 15 to Px.31.
16 (half-word)
WO
0x0000 FIO0CLRU - 0x2009 C01E
FIO1CLRU - 0x2009 C03E
FIO2CLRU - 0x2009 C05E
FIO3CLRU - 0x2009 C07E
FIO4CLRU - 0x2009 C09E
Table 86.
Fast GPIO port output Clear byte and half-word accessible register description
Generic
Register
name
Description
Register
length (bits)
& access
Reset
value
PORTn Register
Address & Name
Table 87.
Fast GPIO port Pin value register (FIO0PIN to FIO7PIN- addresses 0x2009 C014 to
0x2009 C094) bit description
Bit
Symbol
Value Description
Reset
value
31:0
FP0VAL
FP1VAL
FP2VAL
FP3VAL
FP4VAL
Fast GPIO output value Set bits. Bit 0 in FIOxCLR corresponds
to pin Px.0, bit 31 in FIOxCLR corresponds to pin Px.31.
0x0
0
Controlled pin output is set to LOW.
1
Controlled pin output is set to HIGH.