DS3170 DS3/E3 Single-Chip Transceiver
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Table 10-10. Reset and Power-Down Sources
PIN
REGISTER BITS
INTERNAL SIGNALS
RS
T
G
:R
ST
G
:RS
T
DP
P:R
ST
P:R
ST
D
P
P:PD
Gl
oba
l
reset
Gl
oba
ld
p
reset
P
o
rt
reset
Po
rt
d
p
reset
P
o
rt
p
o
w
er
dn
0
F0
F1
F0
F1
1
F1
F0
F1
1
0
1
F1
0
1
0
1
0
X
1
0
1
0
1
0
1
0
X
0
1
0
1
0
1
0
1
F1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
Register Bit States—F0: Forced to 0; F1: Forced to 1; 0: Set to 0; 1: Set to 1; X: Don’t care
Forced: Internally controlled; Set: User controlled
The reset signals in the device are asynchronous so they no not require a clock to put the logic into the reset state.
Clock signals may be needed to make the logic come out of the reset state.
The power-down function disables the appropriate clocks to cause the logic to generate a minimum of power. It
also puts the LIU circuits into the power-down mode. The 8KREF and ONESEC circuits can be powered down by
disabling the 8KREF source. The CLAD can also be powered down by disabling it.
After a global reset, all of the control and status registers are set to their default values and all the other flops are
reset to their reset values. The global register
GL.CR1.RSTDP, and the port register
PORT.CR1.RSTDP and
PORT.CR1.PD bits, are set after the global reset. A valid initialization sequence would be to clear the
PORT.CR1.PD bit, write to all of the configuration registers to set them in the desired modes, then clear the
GL.CR1.RSTDP and
PORT.CR1.RSTDP bits. This would cause the logic in the port to start up in a repeatable
sequence. The device can also be initialized by clearing the
GL.CR1.RSTDP,
PORT.CR1.RSTDP and
PORT.CR1.PD them writing to all of the configuration registers to set them in the desired modes, and clearing all of
the latched status bits. The second initialization scheme could cause the device to temporarily go into modes of
operation that were not requested, but will quickly go into the requested modes of operation.
Some of the IO pins are put in a known state at reset. The transmit LIU outputs TXP and TXN are quiet and will not
drive positive or negative pulses. The global IO pins (GPIO[7:0]) are set as inputs at global reset. The port output
pins (TLCLK, TPOS/TDAT, TNEG, TOHCLK, TOHSOF, TSOFO/TDEN, TCLKO/TGCLK, ROH, ROHCLK,
ROHSOF, RSER, RSOFO/RDEN, RCLKO/RGCLK) are driven low at global or port reset and should stay low until
after the port power-down
PORT.CR1.PD and port data path reset
PORT.CR1.RSTDP bits are cleared.
The
processor port three-state output pins (D[15:0],
RDY, INT) are forced into the high impedance state when the RST
pin is active, but not when the
GL.CR1.RST bit is active.
After reset, the device will be in the default configuration:: The latched status bits are enabled to be cleared on
write. The CLAD is disabled. The global 8KREF and one-second timers are disabled. The line interface is in B3ZS
mode and the LIU is disabled and the transmit line pins are also disabled. The frame mode is DS3 C-bit with
automatic downstream AIS on LOS or OOF is enabled and automatic RDI on LOF, LOS, SEF or AIS is enabled
and automatic FEBE is enabled. Transmit clock comes from the REFCLK pin. The pin inversion on all pins is
disabled.
Individual blocks are reset and powered down when not used determined by the settings in the line mode bits