Parallax BASIC Stamp 2e Programming Manual page 314

SHIFTIN - BASIC Stamp Command Reference
Demo Program (SHIFTIN.bs2)
' This program uses the SHIFTIN instruction to interface with the ADC0831 8-bit
' analog-to-digital converter from National Semiconductor.
'{$STAMP BS2}
ADres VAR BYTE
CS CON 0
AData CON 1
CLK CON 2
HIGH CS
' In the loop below, just three lines of code are required to read the ADC0831. The
' SHIFTIN command does most of the work. The mode argument in the SHIFTIN command
' specifies msb or lsb-first and whether to sample data before or after the clock.
' In this case, we chose msb-first, post-clock. The ADC0831 precedes its data output
' with a dummy bit, which we take care of by specifying 9 bits of data instead of 8.
Again:
LOW CS
SHIFTIN AData, CLK, MSBPOST, [ADres\9] 'Shift in the data.
HIGH CS
DEBUG ? ADres
PAUSE 1000
GOTO Again
Page 312 • BASIC Stamp Programming Manual 2.0b • www.parallaxinc.com
'STAMP directive (specifies a BS2)
'A-to-D result: one byte.
'Chip select is pin 0.
'ADC data output is pin 1.
'Clock is pin 2.
'Deselect ADC to start.
'Activate the ADC0831.
'Deactivate ADC0831.
'Show us the conversion result.
'Wait a second.
'Do it again.
2 2 2
2
e
sx p
NOTE: This is written for the BS2
but can be used for the BS2e,
BS2sx and BS2p also. Locate the
proper source code file or modify
the STAMP directive before
downloading to the BS2e, BS2sx or
BS2p.