LTC1296CCSW datasheet(15/28 Pages) LINER

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LTC1293/LTC1294/LTC1296

129346fs

Interfacing to the Parallel Port of the Intel 8051 Family

The Intel 8051 has been chosen to show the interface

between the LTC1293/4/6 and parallel port microproces-

sors. Usually the signals CS, DIN and CLK are generated

on three port lines and the DOUT signal is read on a fourth

port line. This works very well. One can save a line by tying

the DIN and DOUT lines together. The 8051 first sends the

start bit and DIN to the LTC1294 over the line connected to

P1.2. Then P1.2 is reconfigured as an input and the 8051

reads back the 12-bit A/D result over the same data line.

APPLICATI

I FOR ATIO

Data Exchange Between LTC1294 and MC68HC11

Motorola SPI (MC68HC11)

The MC68HC11 has been chosen as an example of an MPU

with a dedicated serial port. This MPU transfers data MSB-

first and in 8-bit increments. The DIN word sent to the data

the A/D result is read into the MPU. The second 8-bit

transfer clocks B11 through B8 of the A/D conversion

result into the processor. The third 8-bit transfer clocks

the remaining bits B7 through B0 into the MPU. The data

is right justified in the two memory locations. ANDing the

second byte with 0DHEX clears the four most significant

bits. This operation was not included in the code. It can

be inserted in the data gathering loop or outside the loop

when the data is processed.

Hardware and Software Interface to Motorola MC68HC11

CLK

DOUT

MPU

RECEIVED

WORD

LTC1293 TD01

UNI

SGL/

DIFF

ODD/

EVEN

SEL

START

MSBF

B11

B10

DIN

MPU

TRANSMIT

WORD

BYTE 3 (DUMMY)

BYTE 2

SGL

ODD

SEL

BYTE 1

UNI MSBF

START

BYTE 3

BYTE 2

BYTE 1

B11

B10

DON'T CARE

LTC1293 TD01a

CLK

DOUT

LTC1294

ANALOG

INPUTS

SCK

MISO

MC68HC11

DIN

MOSI

BYTE 1

B10

B11

DOUT FROM LTC1294 STORED ON MC68HC11 RAM

BYTE 2

LSB

MSB

#62

#63

LTC1296CCSW Datasheet(PDF) 15 Page - Linear Technology

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