ADE7816 datasheet(36/48 Pages) AD

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ADE7816

Data Sheet

Rev. 0 | Page 36 of 48

REGISTERS

To protect the integrity of the data stored in the data memory

(located at Address 0x4380 to Address 0x43BE), a write protection

mechanism is available. By default, the protection is disabled,

and registers that are located between Address 0x4380 and

Address 0x43BE can be written without restriction. When the

protection is enabled, no writes to these registers are allowed.

Registers can always be read, without restriction, independent

of the write protection state.

To enable the protection, write 0xAD to an internal 8-bit

of 0x80 to an internal 8-bit register located at Address 0xE7E3.

It is recommended that the write protection be enabled before

starting the DSP. If any register requires changing after this time,

disable the protection, change the value, and then reenable the

protection. There is no need to stop the DSP to change these

registers.

To disable the protection, write 0xAD to an internal 8-bit

0x00 to an internal 8-bit register that is located at Address 0xE7E3.

The ADE7816 includes 8-, 16-, and 32-bit, signed and unsigned

registers. All signed registers are in twos complement format.

Some of the internal measurements are 24 bits long and have

been extended to 32 bits prior to communication. This extension

is accomplished in three different ways: sign extending (SE), zero

padding (ZP), or zero padded and sign extended (ZPSE). When

sign extending is used, the sign bit (Bit 23) of the twos complement

signed number is duplicated in the uppermost byte prior to

communication. Zero padding is achieved by writing 0s into the

upper most byte prior to transmission. This format is used for

unsigned numbers only. Zero padded and sign extended formats

are shown in Figure 47 and involve padding the most significant

bits with 0s and sign extending Bits[27:24].

28 27

24 23

24-BIT NUMBER

0000

BITS[27:24] ARE

EQUAL TO BIT 23

BIT 23 IS A SIGN BIT

Figure 47. ZPSE Communication Format

The communication format of each register is specified in the

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