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LTC1090
1090fc
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.
Hardware and Software Interface to Motorola MC68HC05C4
Processor
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
APPLICATIO S I FOR ATIO
WUUU
MNEMONIC DESCRIPTION
BCLR n C0 is cleared (CS goes Low)
LDA Load D
IN
for LTC1090 into ACC
STA Load D
IN
from ACC to SPI data reg. Start SCK
↑
NOP 8 NOPs for timing
↓
LDA Load contents of SPI status reg. into ACC
LDA Load LTC1090 D
OUT
from SPI data reg. into ACC (byte 1)
STA Load LTC1090 D
OUT
into RAM (location A)
STA Start next SPl cycle
↑
NOP 6 NOPs for timing
↓
BSET n C0 is set (CS goes high)
LDA Load contents of SPI status reg. into ACC
LDA Load LTC1090 D
OUT
from SPI data reg. into ACC (byte 2)
STA Load LTC1090 D
OUT
into RAM (location A + 1)
LTC1090
ANALOG
INPUTS
D
OUT
D
OUT
from LTC1090 stored in MC68HCO5C4 RAM
D
IN
SCLK
CO
SCK
MOSI
MISO
MC68HCO5C4
CS
B9
Location A
Location A + 1
byte 1
byte 2
*B9 is MSB in unipolar or sign bit in bipolar
MSB*
LSB
B8 B7 B6 B5 B4 B3 B2
B1 B0 0 0 0 0 0 0
LTC1090 • AI12
MNEMONIC DESCRIPTION
LDA Load D
IN
word for LTC1090 into ACC from RAM
BCLR n C0 cleared (CS goes low)
STA Load D
IN
word for LTC1090 into SCI data reg. from ACC
and start clocking data (LSB first)
↑
NOP 6 NOPs for timing
↓
LDA Load contents of SCI data reg. into ACC (byte 1)
Start next SCI cycle
STA Load LTC1090 D
OUT
word into RAM (Location A)
NOP Timing
BSET n C0 set (CS goes high)
LDA Load contents of SCI data reg. into ACC (byte 2)
STA Load LTC1090 D
OUT
word into RAM (Location A + 1)