ADE7566 datasheet(34/136 Pages) AD

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ADE7566/ADE7569

Preliminary Technical Data

Rev. PrA | Page 34 of 136

ENERGY MEASUREMENT

The ADE7566/ADE7569 offer a fixed function, energy

measurement, digital processing core that provides all the

information needed to measure energy in single-phase energy

meters. The part provides two ways to access the energy

measurements: direct access through SFRs for time sensitive

information and indirect access through address and data SFR

registers for the majority of energy measurements. The Irms,

Vrms, interrupts, and waveform registers are readily available

through SFRs as shown in Table 27. Other energy measurement

information is mapped to a page of memory that is accessed

indirectly through the MADDPT, MDATL, MDATM, and

MDATH SFRs. The address and data registers act as pointers to

the energy measurement internal registers.

ACCESS TO ENERGY MEASUREMENT SFRs

Access to the energy measurement SFRs is achieved by reading

or writing to the SFR addresses detailed in Table 28. The

internal data for the MIRQx SFRs are latched byte by byte into

the SFR when the SFR is read.

The WAV1x, WAV2x, VRMSx, and IRMSx registers are all 3-byte

SFRs. The 24-bit data is latched into these SFRs when the high

byte is read. Reading the low or medium byte before the high

byte results in reading the data from the previous latched sample.

Sample 8051 code to read the Vrms register is shown below.

MOV

R1, VRMSH

//latches data in VrmsH,

VrmsM and VrmsL SFR

MOV

R2, VRMSM

MOV

R3, VRMSL

ACCESS TO INTERNAL ENERGY MEASUREMENT

REGISTERS

Access to the internal energy measurement registers is achieved

by writing to the Energy Measurement Pointer Address SFR

(MADDPT, 0x91). This SRF selects the energy measurement

performed (see Table 27).

Table 27. Energy Measurement Pointer Address SFR

(MADDPT, 0x91)

Bit Number

Description

1 = write, 0 = read

6 to 1

Energy measurement internal register address

Writing to the Internal Energy Measurement Registers

When Bit 7 of the Energy Measurement Pointer Address SFR

(MADDPT, 0x91) is set, the content of the MDATx SFRs

(MDATL, MDATM, and MDATH) is transferred to the internal

energy measurement register designated by the address in the

MADDPT SFR. If the internal register is 1 byte long, only the

MDATL SFR content is copied to the internal register, while the

MDATM SFR and MDATH SFR contents are ignored.

The energy measurement core functions with an internal clock

of 4.096 MHz ∕ 5 or 819.2 kHz. Because the 8052 core functions

with another clock, 4.096MHz ∕ 2CD, synchronization between

the two clock environments when CD = 0 or 1 is an issue. When

data is written to the internal energy measurement, a small wait

period needs to be implemented before another read or write to

these registers can take place.

Sample 8051 code to write 0x0155 to the 2-byte SAGLVL

space is shown below.

MOV

MDATM,#01h

MOV

MDATL,#55h

MOV

MADDPT,#SAGLVL_W (address 0x94)

MOV

A, #05h

DJNZ

ACC, $

;Next Write or read to Energy Measurement

SFR can be done after this.

Reading the Internal Energy Measurement Registers

When Bit 7 of Energy Measurement Pointer Address SFR

(MADDPT, 0x91) is cleared, the content of the internal energy

measurement register designated by the address in MADDPT

is transferred to the MDATx SFRs. If the internal register is

1 byte long, only the MDATL SFR content is updated with a

new value, while the MDATM SFR and MDATH SFR contents

are reset to 0x00.

The energy measurement core functions with an internal clock

of 4.096 MHz ∕ 5 or 819.2 kHz. Because the 8052 core functions

with another clock, 4.096MHz ∕ 2CD, synchronization between

the two clock environments when CD = 0 or 1 is an issue. When

data is read from the internal energy measurement, a small wait

period needs to be implemented before the MDATx SFRs are

transferred to another SFR.

Sample 8051 code to read the peak voltage in the 2-byte VPKLVL

MOV

MADDPT,#VPKLVL_R (address 0x16)

MOV

A, #05h

DJNZ

ACC, $

MOV

DPH, MDATM

MOV

DPL, MDATL

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