EVAL-AD7712EB datasheet(26/28 Pages) AD

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AD7712

Table VIII. 8XC51 Code for Writing to the AD7712

MOV SCON,#00000000B;

Configure 8051 for MODE 0

Operation & Enable Serial Reception

MOV IE,#10010000B;

Enable Transmit Interrupt

MOV IP,#00010000B;

Prioritize the Transmit Interrupt

SETB 91H;

Bring

TFS High

SETB 90H;

Bring

RFS High

MOV R1,#003H;

Sets Number of Bytes to Be Written

in a Write Operation

MOV R0,#030H;

Start Address in RAM for Bytes

MOV A,#00H;

Clear Accumulator

MOV SBUF,A;

Initialize the Serial Port

WAIT:

JMP WAIT;

Wait for Interrupt

INT ROUTINE:

NOP;

Interrupt Subroutine

MOV A,R1;

Load R1 to Accumulator

JZ FIN;

If Zero Jump to FIN

DEC R1;

Decrement R1 Byte Counter

MOV A,@R;

Move Byte into the Accumulator

INC R0;

Increment Address

RLC A;

Rearrange Data—From LSB First

to MSB First

MOV B.0,C; RLC A; MOV B.1,C; RLC A;

MOV B.2,C; RLC A; MOV B.3,C; RLC A;

MOV B.4,C; RLC A; MOV B.5,C; RLC A;

MOV B.6,C; RLC A: MOV B.7,C; MOV A,B;

CLR 93H;

Bring A0 Low

CLR 91H;

Bring

TFS Low

MOV SBUF,A;

Write to Serial Port

RETI;

Return from Subroutine

FIN:

SETB 91H;

Set

TFS High

SETB 93H;

Set A0 High

RETI;

Return from Interrupt Subroutine

AD7712 to 68HC11 Interface

Figure 19 shows an interface between the AD7712 and the

68HC11 microcontroller. The AD7712 is configured for its

external clocking mode, while the SPI port is used on the

68HC11, which is in its single-chip mode. The

DRDY line

from the AD7712 is connected to the Port PC2 input of the

68HC11 so the

DRDY line is polled by the 68HC11. The

DRDY line can be connected to the IRQ input of the 68HC11,

if an interrupt driven system is preferred. The 68HC11 MOSI

and MISO lines should be configured for wired-OR operation.

Depending on the interface configuration, it may be necessary

to provide bidirectional buffers between the 68HC11 MOSI

and MISO lines.

The 68HC11 is configured in the master mode with its CPOL

bit set to a Logic 0 and its CPHA bit set to a Logic 1. With a

10 MHz master clock on the AD7712, the interface will operate

with all four serial clock rates of the 68HC11.

AD7712

SDATA

SCLK

RFS

TFS

PC0

MISO

SCK

PC1

PC2

MODE

PC3

DRDY

SYNC

68HC11

MOSI

DVDD

Figure 19. AD7712 to 68HC11 Interface

EVAL-AD7712EB Datasheet(PDF) 26 Page - Analog Devices

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