LTC1096 Linear Technology, LTC1096 Datasheet - Page 24

• Manufacturer Part Number: LTC1096
• Description: Micropower Sampling 8-Bit Serial I/O A/D Converters
• Manufacturer: Linear Technology

LTC1096/LTC1096L
LTC1098/LTC1098L
Interfacing to the Parallel Port of the
Intel 8051 Family
The Intel 8051 has been chosen to demonstrate the
interface between the LTC1098(L) and parallel port micro-
processors. Normally the CS, CLK and D
be generated on three port lines and the D
on a fourth port line. This works very well. However, we
will demonstrate here an interface with the D
of the LTC1098(L) tied together as described in the
SERIAL INTERFACE section. This saves one wire.
The 8051 first sends the start bit and MUX address to the
LTC1098(L) over the data line connected to P1.2. Then
P1.2 is reconfigured as an input (by writing to it a one) and
the 8051 reads back the 8-bit A/D result over the same
data line.
24
TYPICAL
DATA (D
ANALOG
INPUTS
IN
/D
OUT
CLK
CS
)
CLK AND BEFORE THE 4TH FALLING CLK
LTC1098(L)
AS AN INPUT AFTER THE 4TH RISING
A
PPLICATI
START
8051 P1.2 OUTPUTS DATA
D
8051 P1.2 RECONFIGURED
1
CLK
OUT
D
CS
IN
TO LTC1098(L)
SGL/
DIFF
2
MUX ADDRESS
A/D RESULT
ODD/
SIGN
O
MSBF BIT LATCHED
3
U
BY LTC1098(L)
MSBF
S
IN
P1.4
P1.3
P1.2
4
OUT
signals would
IN
LTC1096/8 • TA06
signal read
8051
LTC1098(L) TAKES CONTROL OF DATA LINE
ON 4TH FALLING CLK
and D
B7
OUT
B6
LABEL
LOOP 1
LOOP
B5
LTC1098(L) SENDS A/D RESULT
MNEMONIC
MOV
SETB
CLR
MOV
RLC
CLR
MOV
SETB
DJNZ
MOV
CLR
MOV
MOV
RLC
SETB
CLR
DJNZ
MOV
SETB
D
R2
OUT
B4
MSB
BACK TO 8051 P1.2
B7
from LTC1098(L) Stored in 8051 RAM
B6
B3
B5
A, #FFH
P1.4
P1.4
R4, #04
A
P1.3
P1.2, C
P1.3
R4, LOOP 1
P1, #04
P1.3
R4, #09
C, P1.2
A
P1.3
P1.3
R4, LOOP
R2, A
P1.4
OPERAND
B2
B4
B3
B1
COMMENTS
D
Make sure CS is high
CS goes low
Load counter
Rotate D
CLK goes low
Output D
CLK goes high
Next bit
Bit 2 becomes an input
CLK goes low
Load counter
Read data bit into Carry
Rotate data bit into Acc.
CLK goes high
CLK goes low
Next bit
Store MSBs in R2
CS goes high
B2
IN
word for LTC1098(L)
B1
LTC1096/8 • TA07
IN
B0
IN
bit into Carry
bit to LTC1098(L)
B0
LSB
LTC1096/8 • TA08