LTC2400CS8 Linear Technology, LTC2400CS8 Datasheet - Page 31

• Manufacturer Part Number: LTC2400CS8
• Description: IC A/D CONV 24BIT MICRPWR 8-SOIC
• Manufacturer: Linear Technology

Specifications of LTC2400CS8

• Mfg Application Notes: Application Note
• Number Of Bits: 24
• Sampling Rate (per Second): 7.5
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

ShiftL
The listing in Figure 34 is a simple assembler routine for
the 68HC11 microcontroller. It uses PORT D, configuring
it for SPI data transfer between the controller and the
LTC2400. Figure 33 shows the simple 3-wire SPI
connection.
The code begins by declaring variables and allocating four
memory locations to store the 32-bit conversion result.
This is followed by initializing PORT D’s SPI configuration.
The program then enters the main sequence. It activates
TYPICAL APPLICATIONS
*****************************************************
* This example program transfers the LTC2400's 32-bit output
* conversion result into four consecutive 8-bit memory locations. *
*****************************************************
*68HC11 register definition
PORTD
*
DDRD
SPSR
*
SPSR
*
SPDR
*
* RAM variables to hold the LTC2400's 32 conversion result
ADlo.bit0 = in0
low SCK
next
high CS
ADhi = (ADhi<<4)+((ADlo&$F000)>>12)
debug ?ADhi
goto Start
Temp = ADlo.bit15
ADlo = ADlo<<1
ADhi = ADhi<<1
ADhi.bit0 = Temp
return
EQU
EQU
EQU
EQU
EQU
Figure 32. This BASIC Stamp Code is an Example of How Easy it is to Retrieve Data from the LTC2400
$1008
$1009
$1028
$1029
$102A
Figure 33. Connecting the LTC2400 to a 68HC11 MCU Using the SPI Serial Interface
Port D data register
" – , – , SS* ,CSK ;MOSI,MISO,TxD ,RxD"
Port D data direction register
SPI control register
"SPIE,SPE ,DWOM,MSTR;SPOL,CPHA,SPR1,SPR0"
SPI status register
"SPIF,WCOL, – ,MODF; – , – , – , – "
SPI data register; Read-Buffer; Write-Shifter
'and sample data line
'Disable the LTC2400
'Discard the lower eight bits
'and display (debug command).
'This routine simply
'performs a 1 bit
'left shift on two
'16 bit variables
U
LTC2400
*
SDO
SCK
CS
7
6
5
the LTC2400’s serial interface by setting the SS output
low, sending a logic low to CS. It next waits in a loop for
a logic low on the data line, signifying end-of-conversion.
After the loop is satisfied, four SPI transfers are com-
pleted, retrieving the conversion. The main sequence ends
by setting SS high. This places the LTC2400’s serial
interface in a high impedance state and initiates another
conversion.
SCK (PD4)
MISO (PD2)
SS (PD5)
68HC11
2400 F33
LTC2400
31