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10.4.3 One Second Reference Generation
The one-second-reference signal is used as an option to update the performance registers on a precise one-
second interval. The generated internal signal should be about 50% duty cycle and it is derived from the Global 8
kHz reference signal by dividing it by 8000. The low to high edge on this signal will set the
ONESL latched
one second detect bit which can generate an interrupt when the
ONESIE interrupt enable bit is set. The
low to high edge can also be used to generate performance monitor updates when
GPM[1:0]=1X.
10.4.4 General-Purpose IO Pins
There are eight general-purpose IO pins that can be used for general IO, global signals and per port alarm signals.
Each pin is independently configurable to be a general-purpose input, general-purpose output, global signal or port
alarm. Two of the GPIO pins are assigned to each port and can be programmed to output one or two alarm
statuses using one or two GPIO pins. One of the two pins assigned to each port can be programmed as global
input or output signals. When the device is bonded out (or has ports powered down) to have 1, 2 or 3 ports active,
the GPIO pins associated with the disabled ports will still operate as either general-purpose inputs, general-
purpose outputs or global signals. When the ports are disabled and
GPIOx[1:0] = 01, the GPIO pin will
be an output driving low. The 8KREFI, TMEI, and PMU signals that can be sourced by the GPIO pin will be driven
low into the core logic when the GPIO pin is not selected for the source of the signal.
lists the purpose and control thereof of the General-Purpose IO Pins.
Table 10-14. GPIO Global Signals
Pin
Global signal
Control bit
GPIO2 8KREFO
output
.G8KOS
GPIO4 8KREFI
input
.G8KIS
GPIO6 TMEI
input
GPIO8 PMU
input
.GPM[1:0]
describes the selection of mode for the GPIO Pins.
Table 10-15. GPIO Pin Global Mode Select Bits
n = port 1 to 4, x = A or B, valid when a GPIO pin is not selected for a global signal
GPIO pin mode
00 Input
01
Port alarm status selected by port
GPIO
10
Output logic 0
11
Output logic 1
lists the various port alarm monitors that can be output on the GPIO pins. The GPIO(A/B)[3:0] bits are
located in the
Register.