AD7887

Rev. D | Page 19 of 24

DOUT

DIN

SCLK

CS

P1.3

P1.0

P1.1

P1.2

AD7887 to MC68HC11

The serial peripheral interface (SPI) on the MC68HC11 is

configured for master mode (MSTR = 1) when the clock

polarity bit (CPOL) = 1 and the clock phase bit (CPHA) = 1.

The SPI is configured by writing to the SPI Control Register

(SPCR)—see the M68HC11 reference manual from Freescale

Semiconductor, Inc., for more information. The serial transfer

takes place as two 8-bit operations. A connection diagram is

shown in Figure 25.

Figure 26. Interfacing to the 8051 Using Input/Output Ports

AD7887 to PIC16C6x/PIC16C7x

DOUT

DIN

SCLK

CS

SCLK/PD4

MISO/PD2

MOSI/PD3

PA0

The PIC16C6x synchronous serial port (SSP) is configured as an

SPI master with the clock polarity bit = 1. This is done by writing to

the synchronous serial port control register (SSPCON). See the

PIC16/PIC17 Microcontroller User Manual. Figure 27 shows the

hardware connections needed to interface to the PIC16C6x/

PIC16C7x. In this example, input/output port RA1 is being used to

pulse CS. This microcontroller only transfers eight bits of data

during each serial transfer operation. Therefore, two consecutive

read/write operations are needed.

Figure 25. Interfacing to the MC68HC11

AD7887 to 8051

DOUT

DIN

SCLK

CS

PIC16C6x/

SCK/RC3

SDO/RC5

RA1

SDI/RC4

It is possible to implement a serial interface using the data ports

on the 8051. This allows a full duplex serial transfer to be imple-

mented. The technique involves bit-banging an input/output

port (for example, P1.0) to generate a serial clock and using two

other input/output ports (for example, P1.1 and P1.2) to shift

data in and out—see Figure 26.

Figure 27. Interfacing to the PIC16C6x/PIC16C7x