LTC1290DCJ Datasheet, PDF (28/32 Pages) Linear Integrated Systems – Single Chip 12-Bit Data Acquisition System

LTC1290
TYPICAL APPLICATI S
SNEAK-A-BIT Code
D_OUT from LTC1290 in MC68HC05C4 RAM
Sign
LOCATION $77 B12 B11 B10 B9 B8 B7 B6 B5
LOCATION $87 B4
B3 B2
LSB
B1 B0
Filled with 0s
D_IN Words for LTC1290
MUX Addr.
(ODD/SIGN)
MSBF
UNI
Word
Length
D_IN1 0 0 1 1 1 1 1 1
D_IN2 0 1 1 1 1 1 1 1
D_IN3 0 0 1 1 1 1 1 1
1290 TA06
SNEAK-A-BIT Code for the LTC1290 Using the MC68HC05C4
MNEMONIC
DESCRIPTION
LDA
STA
LDA
STA
BSET
JSR
JSR
JSR
JSR
#$50
$0A
#$FF
$06
0,$02
READ –/+
READ –/+
READ –/+
CHK Sign
Configuration Data for SPCR
Load Configuration Data into $0A
Configuration Data for Port C DDR
Load Configuration Data into Port C DDR
Make Sure CS is High
Dummy Read Configures LTC1290
for next read
Read CH6 with Respect to CH7
Read CH7 with Respect to CH6
Determines which Reading has Valid Data,
Converts to 2’s Complement and
Stores in RAM
28
SNEAK-A-BIT Code for the LTC1290 Using the MC68HC05C4
MNEMONIC
DESCRIPTION
READ –/+: LDA #$3F
JSR TRANSFER
LDA $60
STA $71
LDA $61
STA $72
RTS
READ +/–: LDA #$7F
JSR TRANSFER
LDA $60
STA $73
LDA $61
STA $74
RTS
TRANSFER: BCLR 0,$02
STA $0C
LOOP 1: TST $0B
BPL LOOP 1
LDA $0C
STA $0C
STA $60
LOOP 2: TST $0B
BPL LOOP 2
BSET 0,$02
LDA $0C
STA $61
RTS
CHK SIGN: LDA $73
ORA $74
BEQ MINUS
CLC
ROR $73
ROR $74
LDA $73
STA $77
LDA $74
STA $87
BRA END
MINUS: CLC
ROR $71
ROR $72
COM $71
COM $72
LDA $72
ADD #$01
STA $72
CLRA
ADC $71
STA $71
STA $77
LDA $72
STA $87
END:
RTS
Load D_IN Word for LTC1290 into ACC
Read LTC1290 Routine
Load MSBs from LTC1290 into ACC
Store MSBs in $71
Load LSBs from LTC1290 into ACC
Store LSBs in $72
Return
Load D_IN Word for LTC1290 into ACC
Read LTC1290 Routine
Load MSBs from LTC1290 into ACC
Store MSBs in $73
Load LSBs from LTC1290 into ACC
Store LSBs in $74
Return
CS Goes Low
Load D_IN into SPI, Start Transfer
Test Status of SPIF
Loop to Previous Instruction if Not Done
Load Contents of SPI Data Reg. into ACC
Start Next Cycle
Store MSBs in $60
Test Status of SPIF
Loop to Previous Instruction if Not Done
CS Goes High
Load Contents of SPI Data Reg. into ACC
Store LSBs in $61
Return
Load MSBs of ± Read into ACC
Or ACC (MSBs) with LSBs of ± Read
If Result is 0 Go to Minus
Clear Carry
Rotate Right $73 Through Carry
Rotate Right $74 Through Carry
Load MSBs of ± Read into ACC
Store MSBs in RAM Location $77
Load LSBs of ± Read into ACC
Store LSBs in RAM Location $87
Go to End of Routine
Clear Carry
Shift MSBs of ± Read Right
Shift LSBs of ± Read Right
1’s Complement of MSBs
1’s Complement of LSBs
Load LSBs into ACC
Add 1 to LSBs
Store ACC in $72
Clear ACC
Add with Carry to MSBs. Result in ACC
Store ACC in $71
Store MSBs in RAM Location $77
Load LSBs in ACC
Store LSBs in RAM Location $87
Return
1290fe