XOSC32K

32 KHz External Crystal Oscillator (XOSC32K) Control

  0x14 16 PAC Write-Protection 0x00000080  
Parent topic: Register Description

32 KHz External Crystal Oscillator (XOSC32K) Control

Bit  15 14 13 12 11 10 9 8  
        WRTLOCK   STARTUP[2:0]  
Access        R/W   R/W R/W R/W  
Reset        0   0 0 0  
Bit  7 6 5 4 3 2 1 0  
  ONDEMAND RUNSTDBY   EN1K EN32K XTALEN ENABLE    
Access  R/W R/W   R/W R/W R/W R/W    
Reset  1 0   0 0 0 0    

Bit 12 – WRTLOCK: Write Lock

Write Lock

This bit locks the XOSC32K register for future writes, effectively freezing the XOSC32K configuration.

ValueDescription
0 The XOSC32K configuration is not locked.
1 The XOSC32K configuration is locked.

Bits 10:8 – STARTUP[2:0]: Oscillator Start-Up Time

Oscillator Start-Up Time

This bit field selects the XOSC32K crystal oscillator stabilization time.

Important: This stabilization time is for guidance only. A major component of crystal start-up time is based on the second party crystal MFG parasitics that are outside the scope of this specification. If this is a major concern, the customer would need to characterize this based on their design choices.
Table 1. Stabilization Time for 32.768 kHz External Crystal Oscillator (1)
STARTUP[2:0] Number of OSCULP32K Clock Cycles Approximate Equivalent Time
 (2)[s]
0x0 2048 0.06
0x1 4096 0.13
0x2 16384 0.5
0x3 32768 1
0x4 65536 2
0x5 131072 4
0x6 262144 8
0x7 Reserved Reserved
Notes:
  1. 1.The OSCULP32K oscillator is used to clock the start-up counter.
  2. 2.Actual Start-Up time is the number of selected OSCULP32K cycles + 3 XOSC32K cycles.

Bit 7 – ONDEMAND: On Demand Control

On Demand Control

This bit controls how the XOSC32K behaves when a peripheral clock request is detected. For details, refer to XOSC32K Sleep Behavior.

Bit 6 – RUNSTDBY: Run in Standby

Run in Standby

This bit controls how the XOSC32K behaves during Standby sleep mode. For details, refer to XOSC32K Sleep Behavior.

Bit 4 – EN1K: 1KHz Output Enable

1KHz Output Enable

ValueDescription
0 The 1KHz output is disabled.
1 The 1KHz output is enabled.

Bit 3 – EN32K: 32KHz Output Enable

32KHz Output Enable

ValueDescription
0 The 32KHz output is disabled.
1 The 32KHz output is enabled.

Bit 2 – XTALEN: Crystal Oscillator Enable

Crystal Oscillator Enable

This bit controls the connections between the I/O pads and the external clock or crystal oscillator.
ValueDescription
0 External clock connected on XIN32. XOUT32 can be used as general-purpose I/O.
1 Crystal connected to XIN32/XOUT32.

Bit 1 – ENABLE: Oscillator Enable

Oscillator Enable

ValueDescription
0 The oscillator is disabled.
1 The oscillator is enabled.