LTC1290CCJ Datasheet, PDF (18/32 Pages) Linear Technology – Single Chip 12-Bit Data Acquisition System

LTC1290
APPLICATI S I FOR ATIO
8051 Code
MNEMONIC
CONT
LOOP
MOV P1,#02H
CLR P1.3
SETB P1.4
MOV A,#0EH
CLR P1.4
MOV R4,#08H
NOP
MOV C,P1.1
RLC A
MOV P1.2,C
SETB P1.3
CLR P1.3
DJNZ R4,LOOP
MOV R2,A
MOV C,P1.1
CLR A
RLC A
SETB P1.3
CLR P1.3
MOV C,P1.1
RLC A
SETB P1.3
CLR P1.3
MOV C,P1.1
RLC A
SETB P1.3
CLR P1.3
MOV C, P1.1
RRC A
RRC A
RRC A
RRC A
MOV R3,A
SETB P1.3
CLR P1.3
SETB P1.4
COMMENTS
Bit 1 Port 1 Set as Input
SCLK Goes Low
CS Goes High
D_IN Word for LTC1290
CS Goes Low
Load Counter
Delay for Deglitcher
Read Data Bit Into Carry
Rotate Data Bit Into ACC
Output D_IN Bit to LTC1290
SCLK Goes High
SCLK Goes Low
Next Bit
Store MSBs in R2
Read Data Bit Into Carry
Clear ACC
Rotate Data Bit Into ACC
SCLK Goes High
SCLK Goes Low
Read Data Bit Into Carry
Rotate Data Bit Into ACC
SCLK Goes High
SCLK Goes Low
Read Data Bit Into Carry
Rotate Data Bit Into ACC
SCLK Goes High
SCLK Goes Low
Read Data Bit Into Carry
Rotate Right Into ACC
Rotate Right Into ACC
Rotate Right Into ACC
Rotate Right Into ACC
Store LSBs in R3
SCLK Goes High
SCLK Goes Low
CS Goes High
DELAY
MOV R5,#0BH Load Counter
DJNZ R5,DELAY Go to Delay if Not Done
Sharing the Serial Interface
The LTC1290 can share the same 3-wire serial interface
with other peripheral components or other LTC1290s (see
Figure 5). In this case, the CS signals decide which
LTC1290 is being addressed by the MPU.
ANALOG CONSIDERATIONS
1. Grounding
The LTC1290 should be used with an analog ground plane
and single point grounding techniques.
AGND (Pin 11) should be tied directly to this ground plane.
DGND (Pin 10) can also be tied directly to this ground
plane because minimal digital noise is generated within
the chip itself.
V_CC (Pin 20) should be bypassed to the ground plane with
a 22µF tantalum with leads as short as possible. V ^– (Pin
12) should be bypassed with a 0.1µF ceramic disk. For
single supply applications, V ^– can be tied to the ground
plane.
It is also recommended that REF ^– (Pin 13) and COM (Pin
9) be tied directly to the ground plane. All analog inputs
should be referenced directly to the single point ground.
Digital inputs and outputs should be shielded from and/or
routed away from the reference and analog circuitry.
18
21 0
OUTPUT PORT
3
SERIAL DATA
3
CS
MPU
LTC1290
3
CS
LTC1290
3
CS
LTC1290
3-WIRE SERIAL
INTERFACE TO OTHER
PERIPHERALS OR LTC1290s
8 CHANNELS 8 CHANNELS 8 CHANNELS
Figure 5. Several LTC1290s Sharing One 3-Wire Serial Interface
LTC1290 F05
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