User guide

71M6533-DB Demo Board User’s Manual
Page: 31 of 75 ` REV 3
MPU STATUS WORD
The MPU maintains the status of certain meter and I/O related variables in the Status Word. The Status Word is
located at address 0x21. The bit assignments are listed in Table 1-7.
Status
Word Bit
Name
DESCRIPTION
0
CREEP
Indicates that all elements are in creep mode. The CE’s pulse variables
will be “jammed” with a constant value on every accumulation interval to
prevent spurious pulses. Note that creep mode therefore halts pulsing
even when the CE’s pulse mode is “internal”.
1
MINVC
Element C has a voltage below VThrshld. This forces that element into
creep mode.
2
PB_PRESS
A push button press was recorded at the most recent reset or wake from
a battery mode.
3
SPURIOUS
An unexpected interrupt was detected.
4
MINVB
Element B has a voltage below VThrshld. This forces that element into
creep mode.
5
MAXVA
Element A has a voltage above VThrshldP.
6
MAXVB
Element B has a voltage above VThrshldP.
7
MAXVC
Element C has a voltage above VThrshldP.
8
MINVA
Element A has a voltage below VThrshld. This forces that element into
creep mode. It also forces the frequency and main edge count to zero.
9
WD_DETECT
The most recent reset was a watchdog reset. This usually indicates a
software error.
10
MAXIN
The neutral current is over INThrshld. In a real meter this could indicate
faulty distribution or tampering.
11
MAXIA
The current of element A is over IThrshld. In a real meter this could
indicate overload.
12
MAXIB
The current of element B is over IThrshld. In a real meter this could
indicate overload.
13
MAXIC
The current of element C is over IThrshld. In a real meter this could
indicate overload.
14
MINT
The temperature is below the minimum, -40C, established in option_gbl.h.
This is not very accurate in the demo code, because the calibration
temperature is usually poorly controlled, and the default temp_nom is
usually many degrees off. –40C is the minimum recommended operating
temperature of the chip.
15
MAXT
The temperature is above the maximum, 85C, established in option_gbl.h.
This is not very accurate in the demo code, because the calibration
temperature is usually poorly controlled, and the default temp_nom is
usually many degrees off. 85C is the maximum recommended operating
temperature of the chip.
16
BATTERY_BAD
Just after midnight, the demo code sets this bit if VBat < VBatMin. The
read is infrequent to reduce battery loading to very low values. When the
battery voltage is being displayed, the read occurs every second, for up to
20 seconds.
17
CLOCK_TAMPER
Clock set to a new value more than two hours from the previous value.
18
CAL_BAD
Set after reset when the read of the calibration data has a bad longitudinal
redundancy check or read failure.
19
CLOCK_UNSET
Set when the clock’s current reading is A) More than a year after the
previously saved reading, or B) Earlier than the previously saved reading,
or C) There is no previously saved reading.