GP2021 Datasheet, PDF (13/62 Pages) Mitel Networks Corporation – GPS 12 channel Correlator Advance Information

GP2021
Pin Name
NW<3:0> / NC
NRD / NC
NRAM
(standard interface mode)
NRAM
(ARM system mode)
NROM / NC
NSPARE_CS/NC
NEEPROM / NC
TXA,TXB
ACCUM_INT
Logic Level
Low
Low
Low
NB RAM
High Impedance
High Impedance
High Impedance
Low
High Impedance
Pin Name
MEAS_INT
ABORT / MICRO_CLK
MCLK / NC
ARM_ALE / NC
DBE / NC
NRESET_OP
DISCOP
SAMPCLK
XOUT
Table 4 : Output Logic Levels in Power Down Mode
Logic Level
High Impedance
Low
Low
Low
Low
Low
High Impedance
Low
Active
Hardware Reset Generation
The manner in which a hardware reset occurs depends on
whether the GP2021 is in ARM System mode or Standard
Interface mode. During a hardware reset, the NRESET_OP
pin is taken Low and the reset signal is applied within the
GP2021 to all blocks except the Real Time Clock.
There are 3 sources of hardware resets common to both
ARM System and Standard Interface modes, with an
additional source in Standard Interface mode:
POWER_GOOD: A hardware reset will occur if this pin is
taken Low, as shown in Fig. 9. The purpose of this input is to
detect a power failure. If the NBRAM pin is held Low in ARM
System mode, the internal Power Down mode is not entered
until about 6ns after the falling edge of MICRO_CLK,
otherwise it is entered immediately. This allows for RAM write
cycles to complete sensibly when Battery Backed–Up RAM is
used, with no corruption of RAM data.
Watchdog: An expiry of the watchdog will result in a
hardware reset as shown in Fig. 10. This reset will clear the
watchdog whose time–out period is 2–3 seconds.
PLL_LOCK: The PLL_LOCK pin is used to indicate (when
High),that the phase locked loop in the RF front end, which
generates the master clock, is in lock. This signal is filtered
within the GP2021 and the reset state associated with it is only
de–activated if the PLL_LOCK input has been high for
approximately 50 ms as shown in Fig. 11.
NRESET_IP: In addition to the 3 reset sources described
above, an active Low NRESET_IP pin is available in Standard
Interface mode if the system resets are to be generated
externally. Fig. 12 shows a NRESET_IP generated reset.
Note that the NRESET_OP pin will go High 4 MICRO_CLK
cycles after all hardware reset sources have cleared. This
fulfills the reset requirements of the ARM60 microprocessor.
For information on the state of the registers following a
hardware reset refer to the Detailed Description of Registers
section.
System Error Status Register
This allows the software to determine whether the source
of a hardware reset was from a power failure, a PLL_LOCK
failure, watchdog timeout or from an external reset in Standard
Interface mode. For further information refer to the Detailed
Description of Registers section.
POWER_GOOD
Power Down Mode
NRESET_OP
MICRO_CLK/
MCLK
4 CYCLES
Fig. 9 : POWER_GOOD Hardware Reset Generation (NARMSYS = ‘0’, NBRAM =‘0’)
WATCHDOG
NRESET_OP
122 s
4 CYCLES
MICRO_CLK/
MCLK
Fig. 10 : Watchdog Hardware Reset Genera-
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