' {$STAMP BS2}
' ==============================================================================
'
' File...... Ex23 - 74HC595.BS2
' Purpose... Expanded outputs with 74HC595
' Author.... Parallax
' E-mail.... stamptech@parallaxinc.com
' Started...
' Updated... 01 MAY 2002
'
'
' ==============================================================================
' ------------------------------------------------------------------------------
' Program Description
' ------------------------------------------------------------------------------
' This program demostrates a simple method of turning three Stamp lines into
' eight outputs with a 74HC595 shift register.
' ------------------------------------------------------------------------------
' I/O Definitions
' ------------------------------------------------------------------------------
Clock CON 0 ' shift clock (74HC595.11)
DataOut CON 1 ' serial data out (74HC595.14)
Latch CON 2 ' output latch (74HC595.12)
' ------------------------------------------------------------------------------
' Constants
' ------------------------------------------------------------------------------
DelayTime CON 100
' ------------------------------------------------------------------------------
' Variables
' ------------------------------------------------------------------------------
pattern VAR Byte ' output pattern
' ------------------------------------------------------------------------------
' Initialization
' ------------------------------------------------------------------------------
Initialize:
LOW Latch ' make output and keep low
pattern = %00000001
' ------------------------------------------------------------------------------
' Program Code
' ------------------------------------------------------------------------------
Go_Forward:
GOSUB Out_595
PAUSE DelayTime ' put pattern on 74x595
pattern = pattern << 1 ' shift pattern to the left
IF (pattern = %10000000) THEN Go_Reverse ' test for final position
GOTO Go_Forward ' continue in this direction
Go_Reverse:
GOSUB Out_595
PAUSE DelayTime
pattern = pattern >> 1
IF (pattern = %00000001) THEN Go_Forward
GOTO Go_Reverse
' ------------------------------------------------------------------------------
' Subroutines
' ------------------------------------------------------------------------------
Out_595:
SHIFTOUT DataOut, Clock, MSBFirst, [pattern] ' send pattern to 74x595
PULSOUT Latch, 5 ' latch outputs
RETURN