Production Data
WM8352
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R6 (06h)
15
USE_DEV_P
INS
1
Selects which pins to use for the 2-wire
control:
Interface
Control
0 = Use 2-wire I/F pins as 2-wire interface
1 = Use GPIO 10 and 11 as 2-wire interface,
e.g. to download settings from PIC.
Only applies when CONFIG pins[1:0] = 00.
14:13
DEV_ADDR
[1:0]
00
Selects device address (only valid when
CONF_STS = 00)
00 = 0x34
01 = 0x36
10 = 0x3C
11 = 0x3E
Note: In custom modes (CONF[1:0]≠00), the secondary control interface is never used and the
control bits described here have no effect.
Table 62 Control Interface Switching in Development Mode
14.4.2 STARTING UP IN DEVELOPMENT MODE
In Development mode, the GPIO1 pin is configured as a DO_CONF output (see Section 20), which is
asserted high to indicate that the WM8352 is about to start up. This may be used to trigger the
‘genie’ to configure the WM8352 via the secondary control interface.
Figure 65 Configuration Timing in Development Mode
On completion of the register configuration, the power-up sequence is initiated by writing a logic 1 to
the CONFIG_DONE bit. If the CONFIG_DONE bit is not set before the maximum set-up time has
elapsed (see Figure 65), then the WM8352 will revert to the OFF state.
An alternative implementation is to start up the WM8352 by setting CONFIG_DONE to ‘1’ without
first programming the converter/LDO settings. By this method, the rising edge of the /RST signal may
be used to trigger the WM8352 configuration process after the device has entered the ACTIVE state.
In this case, the DC-DC converters and LDOs turn on immediately when they are enabled (time slots
are no longer relevant because the WM8352 is already in the ACTIVE state). To reduce in-rush
current, any configuration sequence triggered by /RST should therefore include supply staggering in
software (i.e. time delays between powering up individual supply domains).
Note that, whether using DO_CONF or /RST to trigger configuration, the on-chip watchdog imposes
a time-out for configuration; if the WM8352 watchdog is not serviced, it restarts the system. This can
be prevented, if necessary, by disabling the watchdog.
PD, February 2011, Rev 4.4
113
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
