AD6624ASSLASHPCB datasheet(38/40 Pages) AD

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AD6624A

–38–

INTERNAL READ ACCESS

A read is performed by first writing the CAR and AMR as with

a write. The data registers (DR2–DR0) are then read in the reverse

order that they were written. First, the least significant byte of

the data (D[7:0]) is read from DR0. On this transaction, the

high bytes of the data are moved from the internal address

pointed to by the CAR and AMR into the remaining data regis-

ters (DR2–DR1). This data can then be read from the data

registers using the appropriate 3-bit addresses. The number of

data registers used depends solely on the amount of data to be

read or written. Any unused bit in a data register should be

masked out for a read.

Read Pseudocode

int read_micro(ext_address);

main();

{

* This code shows the reading of the first RCF coefficient using

the read_micro function as defined above. The variable address

is the External Address A[2..0].

Internal Address = 0x000

// holding registers for the coefficient

int d2, d1, d0;

// coefficient (20-bits wide)

long coefficient;

// write AMR

write_micro(7, 0x00);

// write LAR

write_micro(6, 0x00);

* read D[7:0] from DR0, All data is moved from the Internal

Registers to the interface registers on this access

d0 = read_micro(0) & 0xFF;

// read D[15:8] from DR1

d1 = read_micro(1) & 0xFF;

// read D[23:16] from DR2

d2 = read_micro(2) & 0x0F;

coefficient = d0 + (d1 << 8) + (d2 << 16);

} // end of main

AD6624AS/PCB 数据表(PDF) 38 Page - Analog Devices

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