LTC1294CCN データシートの表示（PDF） - Linear Technology
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LTC1294CCN Datasheet PDF : 28 Pages
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LTC1293/LTC1294/LTC1296
APPLICATI S I FOR ATIO
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
register starts the SPI process. With three 8-bit transfers,
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.
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.
Data Exchange Between LTC1294 and MC68HC11
CS
CLK
DIN
START
SGL/
DIFF
ODD/
EVEN
SEL
1
SEL
0
UNI
MSBF PS
DON'T CARE
DOUT
MPU
TRANSMIT
WORD
MPU
RECEIVED
WORD
START
0
0
0
1
SGL
ODD
SEL
1
SEL
0
BYTE 1
?
? ??
?
? ??
BYTE 1
B11 B10 B9 B8
B7
B6 B5 B4 B3 B2 B1 B0
UNI MSBF PS X X X X X
BYTE 2
?? ?
0 B11 B10 B9 B8
BYTE 2
X X XX X X XX
BYTE 3 (DUMMY)
B7 B6 B5 B4 B3 B2 B1 B0
BYTE 3
LTC1293 TD01
Hardware and Software Interface to Motorola MC68HC11
DOUT FROM LTC1294 STORED ON MC68HC11 RAM
MSB
#62 O O
O
O B11 B10 B9 B8 BYTE 1
LSB
ANALOG
INPUTS
#63 B7 B6 B5 B4 B3 B2 B1 B0 BYTE 2
CS
CLK
LTC1294
DIN
DOUT
DO
SCK
MC68HC11
MOSI
MISO
LTC1293 TD01a
15
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