wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 109

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

Production Data
w
Table 56 Software Shutdown
As part of the shutdown sequence, the WM8351 asserts the /RST and /MEMRST reset signals,
resets its internal control registers, disables most of its functions, resets the CHIP_ON bit to 0 and
moves to the OFF state. (Note that /MEMRST is an optional output available on GPIO pins only.)
14.3.4
If an undervoltage fault or a limit switch overcurrent fault is detected (eg. during start-up, or when
exiting the HIBERNATE state), the WM8351 will respond according to various configurable options.
The Limit Switch and each of the DC Converters and LDO Regulators may be programmed to
shutdown the system in the event of a fault condition. In these events (where a system shutdown is
selected), the WM8351 will either shut down or will attempt to re-start, depending on the state of the
POWERCYCLE register bit.
If POWERCYCLE = 0, then a fault condition will result in the shutdown of the WM8351, reverting to
the OFF state. If POWERCYCLE = 1, then the WM8351 will make a maximum of 8 attempts to re-
start. Each attempt will be scheduled at 200ms intervals. After 8 consecutive failed attempts, the
WM8351 reverts to the OFF state and resets the power cycling counter. Any subsequent start-up
event again has a maximum of 8 attempts to start up (provided that POWERCYCLE = 1).
Table 57 Controlling Power Cycling
14.3.5
The control registers of the WM8351 are reset when it goes into the OFF state. The
REG_RESET_HIB_MODE control bit provides an option to also reset the internal registers when
exiting the HIBERNATE state.
In Development mode, the register reset in OFF can be disabled using the RECONFIG_AT_ON
register field. See Section 14.4 for a definition of this field.
Table 58 Register Reset Control
R3 (03h)
System
Control 1
R3 (03h)
System
Control
R5 (05h)
System
Hibernate
ADDRESS
ADDRESS
ADDRESS
REGISTER RESET
POWER CYCLING
BIT
BIT
BIT
15
13
3
1
5
CHIP_ON
POWERCYCL
E
REG_RESE
T_HIB_MOD
E
ON_DEB_T
ON_POL
LABEL
LABEL
LABEL
DEFAULT
DEFAULT
DEFAULT
0
0
1
0
0
Indicates whether the system is on or off.
Writing 0 to this bit powers down the whole
chip. Registers which are affected by state
machine reset will get reset.
Once the system is turned OFF it can be
restarted by any of the valid ON event.
ON pin off function debounce time
0 = 10s
1 = 5s
ON pin polarity:
0 = Active high (ON)
1 = Active low (/ON)
Action of the internal register reset signal
when going from Hibernate to Active.
0 = Do not do a register reset when leaving
the hibernate state.
1 = Do a register reset when leaving the
hibernate state
Action to take on a fault (if fault response
is set to shutdown system):
0 = Shut down
1 = Shutdown everything then go through
startup sequence. ie. Reboot the system.
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, June 2009, Rev 4.1
WM8351
109