LTC1090 Linear Technology, LTC1090 Datasheet - Page 16

• Manufacturer Part Number: LTC1090
• Description: Single Chip 10-Bit Data Acquisition System
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
Motorola SPI (MC68HC05C4)
The MC68HC05C4 transfers data MSB first and in 8-bit
increments. Programming the LTC1090 for MSB first
format and 16-bit word length allows the 10-bit data
output to be received by the MPU as two 8-bit bytes with
the final 6 unused bits filled with zeroes by the LTC1090.
LTC1090
16
MNEMONIC
BCLR n
LDA
STA
↑
NOP
↓
LDA
LDA
STA
STA
↑
NOP
↓
BSET n
LDA
LDA
STA
D
Location A
Location A + 1
*B9 is MSB in unipolar or sign bit in bipolar
OUT
Hardware and Software Interface to Motorola MC68HC05C4
Processor
from LTC1090 stored in MC68HCO5C4 RAM
ANALOG
INPUTS
C0 is cleared (CS goes Low)
Load D
Load D
8 NOPs for timing
Load contents of SPI status reg. into ACC
Load LTC1090 D
Load LTC1090 D
Start next SPl cycle
6 NOPs for timing
C0 is set (CS goes high)
Load contents of SPI status reg. into ACC
Load LTC1090 D
Load LTC1090 D
IN
IN
MSB*
B9
B1 B0
LTC1090
U
for LTC1090 into ACC
from ACC to SPI data reg. Start SCK
LSB
SCLK
D
B8 B7 B6 B5 B4 B3 B2
OUT
D
CS
IN
OUT
OUT
OUT
OUT
U
0
from SPI data reg. into ACC (byte 1)
into RAM (location A)
from SPI data reg. into ACC (byte 2)
into RAM (location A + 1)
DESCRIPTION
0
MC68HCO5C4
0
W
CO
SCK
MOSI
MISO
0
0
0
U
LTC1090 • AI12
byte 1
byte 2
Hitachi Synchronous SCI (HD63705)
The HD63705 transfers serial data in 8-bit increments,
LSB first. To accommodate this, the LTC1090 is
programmed for 16-bit word length and LSB first format.
The 10-bit output data is received by the processor as two
8-bit bytes, LSB first. The LTC1090 fills the final 6 unused
bits (after the MSB) with zeroes in unipolar mode and with
the sign bit in bipolar mode.
Hardware and Software Interface to Hitachi HD63705 Processor
MNEMONIC
LDA
BCLR n
STA
↑
NOP
↓
LDA
STA
NOP
BSET n
LDA
STA
Location A
Location A + 1
Location A
Location A + 1
D
OUT
ANALOG
from LTC1090 stored in HD63705 RAM
INPUTS
Load D
C0 cleared (CS goes low)
Load D
and start clocking data (LSB first)
6 NOPs for timing
Load contents of SCI data reg. into ACC (byte 1)
Start next SCI cycle
Load LTC1090 D
Timing
C0 set (CS goes high)
Load contents of SCI data reg. into ACC (byte 2)
Load LTC1090 D
IN
IN
Sign
B9 B9 B9 B9 B9 B9 B9 B8
LTC1090
B7
B7
word for LTC1090 into ACC from RAM
word for LTC1090 into SCI data reg. from ACC
0
SCLK
D
B6 B5 B4 B3 B2 B1 B0
B6 B5 B4 B3 B2 B1 B0
OUT
D
CS
0 0 0 0 0 B9 B8
IN
OUT
OUT
DESCRIPTION
word into RAM (Location A)
word into RAM (Location A + 1)
Bipolar
Unipolar
C0
CK
T
R
HD63705
X
X
MSB
LSB
LSB
LTC1090 • AI13
byte 1
byte 2
byte 1
byte 2
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