ADE7758_15 datasheet(59/72 Pages) AD

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Data Sheet

ADE7758

Rev. E | Page 59 of 72

SERIAL READ OPERATION

During a data read operation from the ADE7758, data is shifted

out at the DOUT logic output on the rising edge of SCLK. As

was the case with the data write operation, a data read must be

preceded with a write to the communications register.

With the ADE7758 in communications mode and CS logic low,

an 8-bit write to the communications register takes place first.

The MSB of this byte transfer must be a 0, indicating that the

next data transfer operation is a read. The seven LSBs of this

byte contain the address of the register that is to be read. The

starts shifting out of the register data on the next

rising edge of SCLK (see

). At this point, the DOUT

logic output switches from a high impedance state and starts

driving the data bus. All remaining bits of register data are

shifted out on subsequent SCLK rising edges. The serial

interface enters communications mode again as soon as the

read is completed. The DOUT logic output enters a high

impedance state on the falling edge of the last SCLK pulse.

ADE7758

Figure 94

The read operation can be aborted by bringing the CS logic

input high before the data transfer is completed. The DOUT

output enters a high impedance state on the rising edge of CS.

When an ADE7758 register is addressed for a read operation,

the entire contents of that register are transferred to the serial

port. This allows the ADE7758 to modify its on-chip registers

without the risk of corrupting data during a multibyte transfer.

Note that when a read operation follows a write operation, the

read command (that is, write to communications register)

should not happen for at least 1.1 μs after the end of the write

operation. If the read command is sent within 1.1 μs of the write

operation, the last byte of the write operation can be lost.

ACCESSING THE ON-CHIP REGISTERS

All ADE7758 functionality is accessed via the on-chip registers.

Each register is accessed by first writing to the communications

description of the serial interface protocol, see the Serial

Interface section.

ADE7758 Datasheet(PDF) 59 Page - Analog Devices