ade7953 Analog Devices, Inc., ade7953 Datasheet - Page 57

• Manufacturer Part Number: ade7953
• Description: Single Phase, Multifunction Metering Ic With Neutral Current Measurement Ade7953
• Manufacturer: Analog Devices, Inc.

CHECKSUM REGISTER
The ADE7953 includes a 32-bit checksum register, CRC
(Address 0x37F), which warns the user if any of the important
configuration, control, or calibration registers are modified. The
checksum register helps to ensure that the meter configuration
is not modified from its desired state during normal operation.
Table 12 lists the registers included in the checksum.
An additional six internal reserved registers are also included in
the checksum. The ADE7953 computes the cyclic redundancy
check (CRC) based on the IEEE 802.3 standard. The contents of
the registers are introduced one by one into a linear feedback
shift register (LFSR) based generator, starting with the least
significant bit. The 32-bit result is written to the CRC register.
The CRC is disabled by default and can be enabled by setting
the CRC_ENABLE bit (Bit 8) of the CONFIG register (Address
0x102). When this bit is set, the CRC is computed. Because the
CRC is disabled by default, the default value is 0xFFFFFFFF.
Table 12. Registers Included in the Checksum
Register Name
LCYCMODE
PGA_V
PGA_IA
PGA_IB
CONFIG
CF1DEN
CF2DEN
CFMODE
PHCALA
PHCALB
ALT_OUTPUT
ACCMODE
IRQENA
IRQENB
Configuration and Control Registers
Address
0x004
0x007
0x008
0x009
0x102
0x103
0x104
0x107
0x108
0x109
0x110
0x201 and 0x301
0x22C and 0x32C
0x22F and 0x32F
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Register Name
AIGAIN
VGAIN
AWGAIN
AVARGAIN
AVAGAIN
AIOS
AIRMSOS
VOS
VRMSOS
AWATTOS
AVAROS
AVAOS
BIGAIN
BWGAIN
BVARGAIN
BVAGAIN
BIOS
BIRMSOS
BWATTOS
BVAROS
BVAOS
The checksum can be used to ensure that the registers included
in the checksum are not inadvertently changed by periodically
reading the value in the CRC register (Address 0x37F) after the
meter is configured. If two consecutive readings differ, it can be
assumed that one of the registers has changed value and, therefore,
the configuration of the ADE7953 has changed. The recommended
response is to issue a hardware/software reset, which resets all
ADE7953 registers, including reserved registers, to their default
values. The ADE7953 should then be reconfigured with the
design-specific settings.
An interrupt associated with the checksum feature can provide
an external warning signal on the IRQ pin if the CRC register
value changes after initial configuration. This interrupt is dis-
abled by default and can be enabled by setting the CRC bit (Bit 21)
in the IRQENA register (Address 0x22C and Address 0x32C).
When this interrupt is enabled, an external interrupt is issued
if the CRC value changes from the value that it held at the time
that it was enabled.
Calibration Registers
Address
0x280 and 0x380
0x281 and 0x381
0x282 and 0x382
0x283 and 0x383
0x284 and 0x384
0x285 and 0x385
0x286 and 0x386
0x287 and 0x387
0x288 and 0x388
0x289 and 0x389
0x28A and 0x38A
0x28B and 0x38B
0x28C and 0x38C
0x28E and 0x38E
0x28F and 0x38F
0x290 and 0x390
0x291 and 0x391
0x292 and 0x392
0x295 and 0x395
0x296 and 0x396
0x297 and 0x397
ADE7953