' =========================================================================
'
'   File...... ADC0834.BS2
'   Purpose...
'   Author.... Jon Williams
'   E-mail.... jwilliams@parallax.com
'   Started...
'   Updated... 14 MAR 2005
'
'   {$STAMP BS2}
'   {$PBASIC 2.5}
'
' =========================================================================


' -----[ Program Description ]---------------------------------------------
'
' *** NOT TESTED ***
'
' Connect 1K resistor between Stamp Dio pin and ADC0834.10 (data out) to
' prevent a damage in the event of a data collision.  Tie ADC DI and DO
' pins together.


' -----[ Revision History ]------------------------------------------------


' -----[ I/O Definitions ]-------------------------------------------------

CS              PIN     15                      ' ADC0834.2
Dio             PIN     14                      ' ADC0834.13 / ADC0834.10
Clk             PIN     13                      ' ADC0834.12


' -----[ Constants ]-------------------------------------------------------


' -----[ Variables ]-------------------------------------------------------

chan            VAR     Nib                     ' channel number
mux             VAR     Nib                     ' ADC mux bits
adc             VAR     Byte(4)                 ' channel data


' -----[ EEPROM Data ]-----------------------------------------------------


' -----[ Initialization ]--------------------------------------------------

Reset:
  HIGH CS


' -----[ Program Code ]----------------------------------------------------

Main:
  DEBUG HOME
  FOR chan = 0 TO 3
    GOSUB Read_0834
    DEBUG "CS", DEC1 chan, ": ", DEC3 adc(chan), CR
  NEXT
  GOTO Main
  END


' -----[ Subroutines ]-----------------------------------------------------

' Reads ADC0834 inputs as single-ended
' -- input to read is passed in 'chan' (0 - 3)

Read_0834:
  LOW CS
  LOOKUP chan, [%100, %110, %101, %111], mux
  SHIFTOUT Dio, CLk, MSBFIRST, [1\1, mux\3]     ' send start, mux
  SHIFTIN Dio, Clk, MSBPOST, [adc(chan)\8]      ' read selected input
  HIGH CS
  RETURN 