
144
For the GPIO events, the polarity of the edge used to set the status bit and generate a PME is
controlled by the polarity bit of the GPIO control register. For non-inverted polarity (default) the status
bit is set on the low-to-high edge. If the EETI function is selected for a GPIO then both a high-to-low and
a low-to-high edge will set the corresponding PME status bits. Status bits are cleared on a write of ‘1’.
The PME Wake registers also include status and enable bits for the fan tachometer input.
See the “Keyboard and Mouse PME Generation” section for information about using the keyboard and
mouse signals to generate a PME.
The P12 and P16 bits enable a PME event on single high-to-low edge or on both high-to-low and low-
to-high edges. Default is single edge. There is also a polarity select bit in the configuration register at
0xF0 in Logical Device 7. The register that selects the edge, Edge Select register, is located at the
address programmed in the Base I/O Address register in the Logical Device A at an offset of 21h. Refer
also to PME Status and Enable register 9. See the Runtime Registers sections for description on these
registers.
If both edges are selected for generating a PME via P12 or P16, then the PME is asserted on each
edge until the corresponding PME status bit is cleared.
Note that P12 and P16 status bits are cleared by a write of ‘1’. The SMI generated by P12 and P16 is
deasserted when the associated PME status bit is cleared.
In the LPC47B37x the nIO_PME pin can be programmed to be an open drain, active low, driver. The
LPC47B37x nIO_PME pin is fully isolated from other external devices that might pull the nIO_PME
signal low; i.e., the nIO_PME signal is capable of being driven high externally by another active device
or pullup even when the LPC47B37x Vcc is grounded, providing VTR power is active. The LPC47B37x
nIO_PME driver sinks 6mA at .55V max (see section 4.2.1.1 DC Specifications, page 122, in the PCI
Local Bus Specification, Revision 2.1).
The PME registers are run-time registers as follows. These registers are located in system I/O space at
an offset from Runtime Registers Block, the address programmed in Logical Device A at registers 0x60
and 0x61.
The following registers are for GPIO PME events:
§
PME Wake Status 2 (PME_STS2), PME Wake Enable 2 (PME_EN2)
§
PME Wake Status 3 (PME_STS3), PME Wake Enable 3 (PME_EN3)
§
PME Wake Status 4 (PME_STS4), PME Wake Enable 4 (PME_EN4)
§
PME Wake Status 5 (PME_STS5), PME Wake Enable 5 (PME_EN5)
§
PME Wake Status 7 (PME_STS7), PME Wake Enable 7 (PME_EN7)
The PME Wake Status 6 (PME_STS6), PME Wake Enable 6 (PME_EN6) registers are for the device
interrupt PME events.
The PME Wake Status 1 (PME_STS1), PME Wake Enable 1 (PME_EN1) registers are for pin and
internal function PME events.
See PME register description in the Runtime Register Section.