Datasheet

13
LTC1291
1291fa
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Sharing the Serial Interface
The LTC1291 can share the same 3-wire serial interface
with other peripheral components or other LTC1291s
LABEL MNEMONIC OPERAND COMMENTS
SETB P1.4 CS GOES HIGH
CONT MOV A,#98H DIN WORD FOR LTC1291
CLR P1.4 CS GOES LOW
MOV R4,#05H LOAD COUNTER
LOOP1 RLC A ROTATE DIN BIT INTO CARRY
CLR P1.3 CLK GOES LOW
MOV P1.2,C OUTPUT DIN BIT TO LTC1291
SETB P1.3 CLK GOES HIGH
DJNZ R4,LOOP1 NEXT DIN BIT
MOV P1,#04H P1.2 BECOMES AN INPUT
CLR P1.3 CLK GOES LOW
MOV R4,#09H LOAD COUNTER
LOOP MOV C,P1.2 READ DATA BIT INTO CARRY
RLC A ROTATE DATA BIT (B3) INTO ACC
SETB P1.3 CLK GOES HIGH
CLR P1.3 CLK GOES LOW
DJNZ R4,LOOP NEXT DOUT BIT
MOV R2,A STORE MSBS IN R2
MOV C,P1.2 READ DATA BIT INTO CARRY
SETB P1.3 CLK GOES HIGH
LABEL MNEMONIC OPERAND COMMENTS
8051 Code
(Figure 3). The CS signals decide which LTC1291 is being
addressed by MPU.
Figure 3. Several LTC1291s Sharing One 3-Wire Serial Interface
LTC1291
2 CHANNELS 2 CHANNELS
2 CHANNELS
CS
CS
CS
3
3
33
3-WIRE SERIAL
INTERFACE TO OTHER
PERIPHERALS OR LTC1291s
2
10
OUTPUT PORT
SERIAL DATA
MPU
LTC1291 F03
LTC1291 LTC1291
CLR P1.3 CLK GOES LOW
CLR A CLEAR ACC
RLC A ROTATE DATA BIT (B3) INTO ACC
MOV C,P1.2 READ DATA BIT INTO CARRY
RLC A ROTATE DATA BIT (B2) INTO ACC
SETB P1.3 CLK GOES HIGH
CLR P1.3 CLK GOES LOW
MOV C,P1.2 READ DATA BIT INTO CARRY
RLC A ROTATE DATA BIT (B1) INTO ACC
SETB P1.3 CLK GOES HIGH
CLR P1.3 CLK GOES LOW
MOV C,P1.2 READ DATA BIT INTO CARRY
SETB P1.4 CS GOES HIGH
RRC A ROTATE DATA BIT (B0) INTO ACC
RRC A ROTAGE RIGHT INTO ACC
RRC A ROTAGE RIGHT INTO ACC
RRC A ROTAGE RIGHT INTO ACC
MOV R3,A STORE LSBs IN R3
AJMP CONT START NEXT CONVERSION
In this example the input MUX is configured to accept a
differential input between CH0 and CH1. The result from
the conversion is clocked out MSB-first.