The following GPIOs have “either edge triggered interrupt” (EETI) input capability. These GPIOs can generate a
PME and an SMI on both a high-to-low and a low-to-high edge on the GPIO pin. These GPIOs have a status bit in
the MSC_STS status register that is set on both edges. The corresponding bits in the PME and SMI status registers
are also set on both edges.
ꢀ
ꢀ
ꢀ
GP21, GP22
GP41, GP43
GP60, GP61
The following table summarizes the PME and SMI functionality for each GPIO. It also shows the Either Edge
Triggered Interrupt (EETI) input capability for the GPIOs and the power source for the buffer on the I/O pads.
GPIO
PME
SMI
EETI
BUFFER
POWER
NOTES
GP10-GP17
GP20-GP22, GP24-GP26
GP27
GP30, GP31
GP32, GP33
GP35
GP36, GP37
GP40
GP41
GP42
GP43
GP50-GP52
GP53
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
nIO_SMI
Yes
Yes
No
No
No
Yes
Yes
Yes
No
No
GP21, GP22
No
VCC
VCC
VCC
VCC
VCC
VTR
VCC
VCC
VCC
VTR
VCC
VCC
VTR
VCC
VTR
4
4
4
4
5
1
2
2
4
No
No
No
No
No
Yes
No
Yes
No
No
Yes
nIO_PME
Yes
Yes
Yes
4, 6
4
1, 5
4
No
Yes
Yes
GP54-GP57
GP60, GP61
Yes
Yes
No
Yes
3, 4
Note 1: GP35 and GP53 have the IRTX function and their output buffers are powered by VTR so that the
pins are always forced low when not used.
Note 2: GP36-GP37 and GP40 should not be connected to any VTR powered external circuitry. These
pins are not used for wakeup.
Note 3: GP60 and GP61 have LED functionality which must be active under VTR so its buffer is
powered by VTR.
Note 4: These pins can be used for wakeup events to generate a PME while the part is under VTR power
(VCC=0).
Note 5: These pins cannot be used for wakeup events to generate a PME while the part is under VTR power
(VCC=0). The GP32, GP33 and GP53 pins come up as output and low on a VCC POR and hard reset.
Also, GP32 and GP33 pins revert to their non-inverting GPIO input function when VCC is removed from the
part.
Note 6: GP43 defaults to the GPIO function on VCC POR and Hard Reset.
6.14.6 Either Edge Triggered Interrupts
Six GPIO pins are implemented such that they allow an interrupt (PME or SMI) to be generated on both a high-to-low
and a low-to-high edge transition, instead of one or the other as selected by the polarity bit.
The either edge triggered interrupts (EETI) function as follows: If the EETI function is selected for the GPIO pin, then
the bits that control input/output, polarity and open collector/push-pull have no effect on the function of the pin.
However, the polarity bit does affect the value of the GP bit (i.e., register GP2, bit 2 for GP22).
A PME or SMI interrupt occurs if the PME or SMI enable bit is set for the corresponding GPIO and the EETI function
is selected on the GPIO. The PME or SMI status bits are set when the EETI pin transitions (on either edge) and are
cleared on a write of ‘1’. There are also status bits for the EETIs located in the MSC_STS register, which are also
cleared on a write of ‘1’. The MSC_STS register provides the status of all of the EETI interrupts within one register.
The PME, SMI or MSC status is valid whether or not the interrupt is enabled and whether or not the EETI function is
selected for the pin.
SMSC DS – LPC47M14X
Page 114
Rev. 03/19/2001
SMSC [ SMSC CORPORATION ]
