There are several conditions which the device will go through: a digital reset, putting the registers to their default settings and reloading the OTP.
- A WAKE ping/tone is sent to transition
from SHUTDOWN mode or SLEEP mode to ACTIVE mode.
- A WAKE ping/tone is received in ACTIVE
mode.
- The CONTROL1[SOFT_RESET] = 1 command is sent in ACTIVE mode.
- A HW_RESET ping/tone is sent under any
power mode. This generates a POR-like event to the device. Upon the
detection of a HW_RESET ping/tone,
the device will turn off all internal blocks except a bandgap for
tHWRST duration. Afterward, the device will restart in
SHUTDOWN mode.
- Internal power supply faults. See Section 8.3.5.4 for details.
- AVDD UV, DVDD UV is detected.
- A HFO or LFP watchdog fault will reset the digital.
Apart from the full reset cases, the following
conditions will only reset the UART engine. These
conditions mainly affect the base device because UART is used to talk to the
host MCU. In the base device, the
FAULT_COMM1[COMMCLR_DET] = 1 will be set. These conditions do not affect the stack devices
because UART is inactive in those devices.
- A SLEEPtoACTIVE ping is sent to transition from SLEEP mode
to ACTIVE mode.
- The following conditions not only clear the UART engine
and set the [COMMCLR_DET] = 1, they also set
FAULT_COMM1[STOP_DET] = 1 as an indication that an unexpected
UART STOP is detected.
- A SLEEPtoACTIVE ping is sent in ACTIVE mode.
- A COMM CLEAR signal is sent. This is a dedicated
signal to clear the UART engine and instruct the engine to look for
a new start of communication frame. See Section 8.3.5.1.1.1 for more details.