Rainbow Electronics DS3170 - Manual (Page 68)

DS3170 DS3/E3 Single-Chip Transceiver
68 of 233
9.4.4 General-Purpose IO Pins
There are eight general-purpose IO pins that can be used for general IO, global signals and framer alarm signals.
Each pin is independently configurable to be a general-purpose input, general-purpose output, global signal or
framer alarm. Two of the GPIO pins can be programmed to output one or two framer alarm statuses. One of the
two pins assigned to framer alarms can be programmed as global input or output signals. When the port is
powered down or reset and
GL.GIOCR. 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.
Table 9-14 lists the purpose and control thereof of the General-Purpose IO Pins.
Table 9-14. GPIO Global Signals
PIN GLOBAL SIGNAL CONTROL BIT
GPIO2 8KREFO output GL.CR2 .G8KOS
GPIO4 8KREFI input GL.CR2 .G8KIS
GPIO6 TMEI input GL.CR1 .MEIMS
GPIO8 PMU input GL.CR1 .GPM[1:0]
Table 9-15 describes the selection of mode for the GPIO Pins.
Table 9-15. GPIO Pin Global Mode Select Bits
GL.GIOCR .GPIOSx GPIO PIN MODE
00 Input
01
Framer alarm status selected
by port GPIO
10 Output logic 0
11 Output logic 1
x = A or B, valid when a GPIO pin is not selected for a global signal
Table 9-16 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 PORT.CR4 Register.