WM8321 Datasheet, PDF (116/253 Pages) Wolfson Microelectronics plc – Processor Power Management Subsystem

WM8321
Production Data
22.2.2 POWER STATE STATUS
Setting LEDn_SRC = 01 configures the associated LED to indicate Power State status. Under this
selection, four different conditions may be indicated, as defined in Table 61.
LED DRIVER
DESCRIPTION
Power Sequence Failure
LED1 or
LED2
PVDD Low
ON state
DRIVE MODE
Pulsed sequence
(4 pulses)
Continuous
pulsed
Constant
LED ‘ON’
TIME
1s
250ms
n/a
ON:OFF
DUTY CYCLE
1:1
1:3
n/a
SLEEP state
Continuous
pulsed
Table 61 System Status LED Outputs - Power State Status
250ms
1:7
If more than one of the conditions listed occurs simultaneously, then the LED output pattern is
controlled by the condition in the highest position within the list above.
For example, if the PVDD Low condition occurs while in the ON or SLEEP states, then the LED
output follows the pattern defined for the PVDD Low condition.
The PVDD Low indication is asserted if PVDD is less than the user-selectable threshold
SYSLO_THR, as described in Section 24.4.
Note that, in the case of Power Sequence Failure, the transition to OFF occurs after the 4 LED pulses
have been emitted.
22.2.3 MANUAL MODE
Setting LEDn_SRC = 11 configures the associated LED to operate in Manual Mode, which is
configured using additional register fields.
In Manual Mode, the LED output can be commanded as Off, On (Constant), Continuous Pulsed or
Pulsed Sequence. The selected operation is determined by the LEDn_MODE registers as described
in Table 62.
In Continuous Pulsed mode and Pulsed Sequence mode, the ‘On’ time and the Duty Cycle can be
configured using the LEDn_DUR and LEDn_DUTY_CYC registers respectively.
In Pulsed Sequence mode, the number of pulses in the sequence can be selected using the
LEDn_SEQ_LEN register. On completion of the commanded number of pulses, the LED remains off
until LEDn_MODE or LEDn_SRC is changed to another value.
ADDRESS
R16460
(404Ch)
Status LED1
BIT
LABEL
DEFAULT
DESCRIPTION
9:8 LED1_MODE
[1:0]
00
LED1 Mode
(Controls LED1 in Manual Mode
only.)
00 = Off
01 = Constant
10 = Continuous Pulsed
11 = Pulsed Sequence
5:4 LED1_SEQ_LE
N [1:0]
10
LED1 Pulse Sequence Length
(when LED1_MODE = Pulsed
Sequence)
00 = 1 pulse
01 = 2 pulses
10 = 4 pulses
11 = 7 pulses
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PD, February 2012, Rev 4.0
116