NXP Semiconductors PXN2020, Reference Manual, Page: 147 / 1376

Clocks, Reset, and Power (CRP)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 6-15
6.2.2.12 SoC Status and Control Register (CRP_SOCSC)
The CRP_SOCSC register contains:
• LVI interrupt flags
• LVI interrupt enables
RTCWKF RTC Wakeup Flag. The RTCWKF bit indicates that the RTC match was the wakeup source. A write of 1 clears
the interrupt flag and a write of 0 has no effect.
0 The RTC did not cause the last wakeup.
1 The RTC caused the last wakeup.
APIWKF API Wakeup Flag. The APIWKF bit indicates the API was the wakeup source. A write of 1 clears the interrupt
flag and a write of 0 has no effect.
0 The API did not cause the last wakeup.
1 The API caused the last wakeup.
SLEEP SLEEP Request. The SLEEP bit indicates a request to enter the sleep low-power mode. This bit is cleared
automatically when exiting from SLEEP.
0 No request to enter the sleep low-power mode.
1 Request to enter the sleep low-power mode.
RAMSEL RAM Selects. The RAMSEL bits select which ram configuration retains power during the sleep mode.
000 All RAMs powered down
001 32 KB RAM retains power (0x4000_0000 – 0x4000_7FFF).
010 64 KB RAM retains power (0x4000_0000 – 0x4000_FFFF).
011 128 KB RAM retains power (0x4000_0000 – 0x4001_FFFF).
Other reserved.
WKCLKSEL Wakeup Clock Select. The WKCLKSEL bit selects the clock source used for the wakeup logic synchronizer
and edge detect. WKCLKSEL can be switched only when all wakeup sources are disabled.
0 Clock source for wakeup logic is the 128 kHz IRC.
1 Clock source for wakeup logic is the 16 MHz IRC.
Note: The 128 kHz IRC is not automatically enabled if selected; therefore, it must be enabled before it is
selected for use.
Note: When using the 128 kHz IRC to wake up from SLEEP, the application software must wait at least one
128 kHz clock cycle after entering SLEEP before waking up.
Note: The wakeup flag cannot be cleared until at least three 128 kHz cycles after it has been set.
RTCOVRWKEN RTC Rollover Wakeup Enable. The RTCOVRWKEN bit enables a rollover of the RTC counter to be a wakeup
source for exit from low-power modes.
0 RTC rollover does not generate a wakeup request from low-power mode.
1 RTC rollover generates a wakeup request from low-power modes.
RTCWKEN RTC Wakeup Enable. The RTCWKEN bit enables the RTC to be a wakeup source for exit from low-power
modes.
0 RTC not enabled as a wakeup source.
1 RTC enabled as a wakeup source.
APIWKEN API Wakeup Enable. The APIWKEN bit enables the API to be a wakeup source for exit from low-power
modes.
0 The API does not generate a wakeup request from low-power mode.
1 The API generates a wakeup request from low-power modes.
Table 6-13. CRP_PSCR Field Descriptions (continued)
Field Description