71M6541D Datasheet, PDF (90/166 Pages) Maxim Integrated Products – 0.1% Accuracy Over 2000:1 Current Range Energy Meter ICs

71M6541D/F/G and 71M6542F/G Data Sheet
Table 71: Clear Events for WAKE flags
Flag
Wake on:
Clear Events
WF_TMR Timer expiration
WAKE falls
WF_PB PB pin high level
WAKE falls
WF_RX Either edge RX pin
WAKE falls
WF_DIO4 SEGDIO4 rising edge
WAKE falls
WF_DIO52 SEGDIO52 high level (71M6542F/G only) WAKE falls
WF_DIO55
If OPT_RXDIS = 1 (I/O RAM 0x2457[2]),
wake on SEGDIO55 high
If OPT_RXDIS = 0
wake on either edge of OPT_RX
WAKE falls
WF_RST ^{RESET pin driven high}
WAKE falls, WF_CSTART, WF_RSTBIT,
WF_OVF, WF_BADVDD
WF_RSTBIT ^{RESET bit is set (I/O RAM 0x2200[3])}
WAKE falls, WF_CSTART, WF_OVF,
WF_BADVDD, WF_RST
WF_ERST
WF_OVF
E_RST pin driven high and the ICE
interface must be enabled by driving the
ICE_E pin high.
Watchdog (WD) reset
WAKE falls, WF_CSTART, WF_RST,
WF_OVF, WF_RSTBIT
WAKE falls, WF_CSTART, WF_RSTBIT,
WF_BADVDD, WF_RST
WF_CSTART
Coldstart (i.e., after the application of first
power)
WAKE falls, WF_RSTBIT, WF_OVF,
WF_BADVDD, WF_RST
Note:
“WAKE falls” implies that the internal WAKE signal has been reset, which happens automatically upon
entry into LCD mode or SLEEP mode (i.e., when the MPU sets the LCD_ONLY bit (I/O RAM 0x28B2[6]) or
the SLEEP (I/O RAM 0x28B2[7]) bit). When the internal WAKE signal resets, all wake flags are reset.
Since the various wake flags are automatically reset when WAKE falls, it is not necessary for the MPU to
reset these flags before entering LCD mode or SLEEP mode. Also, other wake events can cause the
wake flag to reset, as indicated above (e.g., the WF_RST flag can also be reset by any of the following
flags setting: WF_CSTART, WS_RSTBIT, WF_OVF, WF_BADVDD)
3.4.2 Wake on Timer
If the part is in SLP or LCD mode, it can be awakened by the Wake Timer. Until this timer times out, the
MPU is in reset due to the internal WAKE signal being low. When the Wake Timer times out, WAKE rises
and within three CK32 cycles, the MPU begins to execute. The MPU can determine that the timer woke it
by checking the WF_TMR wake flag (I/O RAM 0x28B1[2]).
The Wake Timer begins timing when the part enters LCD or SLP mode. Its duration is controlled by the
value in the WAKE_TMR[7:0] register (I/O RAM 0x2880). The timer duration is WAKE_TMR +1 seconds.
The Wake Timer is armed by setting WAKE_ARM = 1 (I/O RAM 0x28B2[5]). It must be armed at least
three RTC cycles before either SLP or LCD modes are initiated. Setting WAKE_ARM presets the timer
with the value in WAKE_TMR and readies the timer to start when the MPU writes to the SLEEP (I/O RAM
0x28B2[7]) or LCD_ONLY (I/O RAM 0x28B2[6]) bits. The timer is neither reset nor disarmed when the
MPU wakes-up. Thus, once armed and set, the MPU continues to be awakened WAKE_TMR[7:0]
seconds after it requests SLP mode or LCD mode (i.e., once written, the WAKE_TMR[7:0] register holds
its value and does not have to be re-written each time the MPU enters SLP or LCD mode. Also, since
WAKE_TMR[7:0] is non-volatile, it also holds its value through resets and power failures).