'MIDI.BS2 - MIDI out program for BASIC Stamp II.
'Copyright 1997-2000 Jeff Mann jefman@utcc.utoronto.ca
'Free for non-commercial use - may not be published or reproduced.
'Get the latest version or add links to:
' http://www.interaccess.org/arg/arg-knowledge/MIDI.BS2

'Stamp II only - Stamp I serial port is not fast enough for MIDI.
'MIDI-out only - Stamp may have trouble receiving MIDI-in because serial
'port is unbuffered. MIDI-in is not covered here.

'This program measures up to 15 potentiometers or other 
'resistive sensors, and sends out 7- or 14-bit MIDI controller data.
'Easily modified to send note or pitchbend data instead. The values
'are not normalized to full-scale; you'll have to add code for that
'or do it in the receving program, eg. Max., taking into account the 
'particular sensor you're using.

'
'See the RCTime command in the Stamp manual for the wiring diagram
'to hook up the pots. Here is the circuit for the MIDI out connector:
'
'
'                 rear view of MIDI out jack  
'                     ___   ___
'     +5 volts       /   l_l   \
'      |            /           \
'      |         NC l o1     3o  l NC
'      |            \  o4 2 5o  /
'      |__/\/\/______\_|  o  |_/___/\/\/_____> to Stamp data pin
'         220 ohms    \___|___/     220 ohms
'                         |
'                        _l_
'                        ///
'                      ground
'
'

'Comment out DEBUG statments for faster response.

'constants, shouldn't change these
midibaudmode con 32780  '31.25kb, 8n1, non-inverted, open collector
'for 14-bit controllers - controller 32 is lsb of controller 0, etc.
controllerLSBoffset con 32
'MIDI status bytes:
controller con %10110000 + midichannel
noteon con %10010000 + midichannel
pitchbend con %11100000 + midichannel

'declare variables
value var word          'holds the 16-bit value read from the pot
pin var nib             'which pin/pot we are reading at the moment
statusbyte var byte     'MIDI status; controller, noteon, or pitchbend
data1 var byte          'first data byte, eg. controller or note number
data2 var byte          'second MIDI data byte, eg. value or velocity

'user configuration - adjust these to suit you
'DANGER - check your circuitry and configure pins accordingly!!
'set unused pins to outputs
DIRS = %1111111111111111 'all outs
OUTS = %0000000000000000 'all low
midichannel con 1       'MIDI transmit channel
midioutpin con 0        'pin connected to MIDI out connector
'check the MIDI spec for a list of controller numbers you can use
controlleroffset con 0  'add to pot's pin # to get MIDI controller #
hipot con 15            'highest pin with a pot to measure
lowpot con 14           'lowest pin with a pot to measure


doit:
   debug HOME
   for pin = lowpot to hipot
     'read the value of the pot
     high pin
     pause 1
     rctime pin, 1, value
     debug "pot ", DEC pin, " reads ", DEC value, CR
     value = value >> 1      'drop the least significant bit

     'send most significant 7 bits as continuous controller msg
     statusbyte = controller         'sending controller message
     data1 = pin + controlleroffset  'controller #
     data2 = value.highbyte
     serout midioutpin, midibaudmode, [statusbyte, data1, data2]

     ''uncomment this section to send 14-bit controller data
     ''send least significant 7 bits
     'data1 = data1 + controllerLSBoffset
     'data2 = value.lowbyte
     'data2 = data2 >> 1     'convert to 7 bits
     ''use running status byte (can leave it out if unchanged)
     'serout midioutpin, midibaudmode, [data1, data2]         
   next
goto doit