71M6531D Datasheet, PDF (52/115 Pages) Teridian Semiconductor Corporation – Energy Meter IC

Data Sheet 71M6531D/F-71M6532D/F
FDS 6531/6532 005
WDT, it is guaranteed that whatever state the part might find itself in, upon watchdog overflow, the part
will be reset to a known state.
Asserting ICE_E will also deactivate the WDT. This is the only method that will work in BROWNOUT
mode. In normal operation, the WDT is reset by periodically writing a one to the WDT_RST bit. The
watchdog timer is also reset when the internal signal WAKE=0 (see Section 2.5 Wake-Up Behavior).
If enabled with the IEN_WD_NROVF register in I/O RAM, an interrupt occurs roughly 1 ms before the WDT
resets the chip. This can be used to determine the cause of a WDT reset since it allows the code to log
its state (e.g. the current PC value, loop counters, flags, etc.) before a WDT reset occurs.
1.5.17 Test Ports (TMUXOUT pin)
One of the digital or analog signals listed in Table 46 can be selected to be output on the TMUXOUT pin.
The function of the multiplexer is controlled with the I/O RAM register TMUX (0x20AA[4:0]), as shown in
Table 46.
Table 46: TMUX[4:0] Selections
TMUX[4:0]
0
1
2
3
4
5
6
7
8 - 0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16 – 0x17
0x18
0x19
0x1A
0x1B
0x1C
0X1D
0X1E
0X1F
Mode
Analog
Analog
Analog
Analog
Analog
Analog
Analog
Analog
–
Digital
Digital
–
Digital
Digital
Digital
–
Digital
Digital
–
Digital
Digital
Digital
Digital
Digital
Function
DGND
Reserved
DGND
Reserved
PLL_2P5
Output of the 2.5 V low-power regulator
Internal VBIAS voltage (nominally 1.6V)
Not used
Reserved
RTC 1-second output
RTC 4-second output
Not used
V1_OK comparator output
Real-time output (RTM) from the CE
WDTR_EN (Comparator 1 Output AND V1LT3)
Not used
RXD (from Optical interface, w/ optional inversion)
MUX_SYNC
Not used
CKMPU (MPU clock)
Pulse output
RTCLK (output of the oscillator circuit, nominally
32,786Hz)
CE_BUSY (busy interrupt generated by CE, 396µs)
XFER_BUSY (transfer busy interrupt generated by the
CE, nominally every 999.7ms)
The TMUXOUT pin may be used for diagnosis purposes or in production test. The RTC 1-second output
may be used to calibrate the crystal oscillator. The RTC 4-second output provides even higher precision.
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