LTC2400 Linear Technology, LTC2400 Datasheet - Page 30

• Manufacturer Part Number: LTC2400
• Description: 24-Bit uPower No Latency ADC in SO-8
• Manufacturer: Linear Technology

LTC2400
TYPICAL APPLICATIONS
Sample Driver for LTC2400 SPI Interface
The LTC2400 has a very simple serial interface that makes
interfacing to microprocessors and microcontrollers very
easy. Shown in Figures 32 and 34 are listings of sample
source codes that can be used to initiate conversions and
retrieve data from the LTC2400.
The listing in Figure 32 was created by Parallax, Inc. (916-
624-8333), for the BASIC Stamp. This code uses indi-
vidual port lines to control the LTC2400’s conversion and
30
'LTC2400
'03/17/99
'
'
'
'
ADlo
ADhi
Ctr
Temp
SDO
SCK
CS
Pwr
Init
Start
var
var
var
var
con
con
con
con
dira = $E
outa = $0
pause 100
high Pwr
pause 1
high CS
pause 125
low CS
for Ctr = 0 to 31
high SCK
gosub ShiftL
Sample Driver
This program is an example showing how to access the
LTC2400 using the Basic Stamp2 from Parallax. Since
the BS2 is based on a 16-bit architecture, only the
upper 16 bits of the 24-bit result are displayed,
although all 24 bits are retrieved.
word
word
byte
bit
0
1
2
3
'A/D result - lower 16 bits
'A/D result - upper 8 bits
'loop counter
'temporary bit used for shift
'Serial data connected to P0
'Serial clock connected to P1
'Chip Select connected to P2
'Stamp supplies power connected to P3
'(Uses only 0.3mA!)
'Set up data direction
'Pwr, CS, and SCK are outputs
'SDO is an input
'Initialize outputs
'Pwr, CS, and SCK are low
'Wait 100mS for I/O to settle
'Power up the LTC2400
'Wait 1mS for power-on sequence
'Disable the device until we
'wish to read it.
'Eight times second
'Enable the LTC2400
'Cycle clock 32 times
U
retrieve the 32-bit result. A fourth port line is used to
power the LTC2400, a vivid example of the converter’s
micropower operation. The program’s main sequence
activates the LTC2400’s serial interface, uses a loop to
retrieve the 32 conversion bits, and then places the
converter’s interface in a high impedance state and start-
ing the next conversion. All bits are retained in variables
ADlo and ADhi. The code can be found on their web site,
www.parallaxinc.com.