ade7953 Analog Devices, Inc., ade7953 Datasheet - Page 56

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

ADE7953
COMMUNICATION VERIFICATION AND SECURITY
The ADE7953 includes three security measures to increase
communication robustness and to help prevent inadvertent
modifications to its internal registers. The write protection,
communication verification, and checksum features can be used
together to help increase the robustness and noise immunity of
the meter design.
WRITE PROTECTION
The ADE7953 provides a simple method for protecting the
internal registers from unexpected write operations. This feature
helps to prevent noise or EMC conditions from changing the
required meter configuration. The write protection feature is
disabled by default to allow the meter to be configured and can
be enabled by writing to the 8-bit WRITE_PROTECT register
(Address 0x040). Only the three LSBs of this register are used.
Bit 0 controls the protection on the 8-bit registers; Bit 1 controls
the protection on the 16-bit registers; Bit 2 controls the protection
on the 24-/32-bit registers. All bits are set to 0 by default to dis-
able the protection. Setting any of these bits to 1 enables write
protection on the corresponding group of registers. When write
protection is enabled, any attempted write operation using the
SPI, I
PROTECT bits to 0 reinstates full access to the register banks.
2
C, or UART interface is ignored. Resetting the WRITE_
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COMMUNICATION VERIFICATION
The ADE7953 includes a set of three registers that allow any
communication via SPI, I
LAST_OP (Address 0x0FD), LAST_ADD (Address 0x1FE),
and LAST_RWDATA registers record the type, address, and
data of the last successful communication, respectively. The
LAST_RWDATA register has four separate addresses, depending
on the length of the successful communication (see Table 11).
Multiple address locations are included to prevent unnecessarily
long communications.
Table 11. Addresses of the LAST_RWDATA Registers
Register Address
Address 0x0FF
Address 0x1FF
Address 0x2FF
Address 0x3FF
After each successful communication with the ADE7953, the
address of the last register that was accessed is stored in the
16-bit LAST_ADD register (Address 0x1FE). This read-only
register stores the value until the next successful read or write
is complete.
The LAST_OP register (Address 0x0FD) stores the type of the
communication, that is, it indicates whether a read or a write
was performed. If the last operation was a write, the LAST_OP
register stores the value 0xCA. If the last operation was a read,
the LAST_OP register stores the value 0x35.
The LAST_RWDATA register stores the data that was written to
or read from the register. Unsuccessful read and write operations
are not reflected in these registers.
2
C, or UART to be verified. The
Length of Read/Write
8 bits
16 bits
24 bits
32 bits