EVAL-AD7710EB datasheet(26/32 Pages) AD

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REV. G

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AD7710

Table VIII. 8XC51 Code for Writing to the AD7710

MOV SCON,#00000000B;

Configure 8051 for MODE 0

Operation and Enable Serial Reception

MOV IE,#10010000B;

Enable Transmit Interrupt

MOV IP,#00010000B;

Prioritize the Transmit Interrupt

SETB 91H;

Bring

TFS High

SETB 90H;

Bring

TFS 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

AD7710 to 68HC11 Interface

Figure 18 shows an interface between the AD7710 and the

68HC11 microcontroller. The AD7710 is configured for its

external clocking mode, while the SPI port is used on the 68HC11

in single-chip mode. The

DRDY line from the AD7710 is con-

nected 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 wire-OR operation. Depending on the interface

configuration, it may be necessary to provide bidirectional buff-

ers between the 68HC11 MOSI and MISO lines.

The 68HC11 is configured in 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 AD7710, the interface operates with all four

serial clock rates of the 68HC11.

AD7710

SDATA

SCLK

RFS

TFS

PC0

MISO

SCK

PC1

PC2

MODE

PC3

DRDY

SYNC

68HC11

MOSI

DVDD

Figure 18. AD7710 to 68HC11 Interface

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