PIC Mapping for midi to LPT decoder for musical robots using Intel 8254 Timer chips:
************************************************************************************
last update: 30.01.2005
Workout for <Vibi>
Default midi channel (set with DIP switch)= 10 ( = binary 1010)
Note that <Vibi> has a slightly different demultiplex board than Tubi. The circuit details are published on the <Vibi> page on the Logos website.
data-port: RB0-RB7 Port B van de PIC, alle bits geflipt: RB7 ==> D0 pic pin 28
RB6 ==> D1 pic pin 27
RB5 ==> D2 pic pin 26
RB4 ==> D3 pic pin 25
RB3 ==> D4 pic pin 24
RB2 ==> D5 pic pin 23
RB1 ==> D6 pic pin 22
RB0 ==> D7 pic pin 21
adres-bus using port A, bits 0-5
Port A van de PIC: RA0 = bit 0 van Reg pic pin 2
RA1 = bit 1 van Reg pic pin 3
RA2 = bit 2 van Reg pic pin 4
RA3 = nc pic pin 5
RA4 = channel select dil switch bit 0 pic pin 6 bit0
RA5 = channel select DIL switch bit 1 pic pin 7 bit1
Port C van de PIC: RC0 = Timer 1 output. Test LED op PIC board (zoals op het <Puff> board)
LED via 1k2 naar GND. pic pin 11
RC1 = nc pic pin 12
RC2 = nc pic pin 13
RC3 = strobe bit (high at rest) pic pin 14
RC4 = channel select DIL switch bit2 pic pin 15 bit 2
RC5 = channel select DIL switch bit3 pic pin 16 bit 3
RC6 = serial output MIDI for debug pic pin 17
RC7 = serial input for MIDI data pic pin 18
(zoals op alle boards)
GROUND: pic pin 19
pic pin 8
POSITIVE SUPPLY: 5V dc pic pin 20
Note1: we connect RA4, RA5, RC4, RC5 to a DIL switch for setting the midi-channel (0-F) (read only on startup or after PIC reset).
Note2: it is essential that all data on the ports be stable before the strobe goes low. At rest, RA3 should always be high. Strobe duration must be 1 microsecond.
Software implementation:
' constants:
strobe = RC3, at rest should always be high.
dport = RB7-RB0 (8 bits)
aport = RA0-RA2 ( 3bits) (RA3 can be kept always low, such that we can always send a nibble)
reg(0) => RA0 = 1, RA1 = 0, RA2 = 1 (dec. 5)
reg(1) => RA0 = 0, RA1 = 0, RA2 = 1 (dec. 4)
reg(2) => RA0 = 1, RA1 = 1, RA2 = 1 (dec. 7)
reg(3) => RA0 = 0, RA1 = 1, RA2 = 1 (dec. 6)
reg(4) => RA0 = 1, RA1 = 0, RA2 = 0 (dec. 1)
reg(5) => RA0 = 0, RA1 = 0, RA2 = 0 (dec. 0)
reg(6) => RA0 = 1, RA1 = 1, RA2 = 0 (dec. 3)
reg(7) => RA0 = 0, RA1 = 1, RA2 = 0 (dec. 2)
global variables:
midichannel as byte
dampmode as byte
sustain as byte
' procedure prototypes:
Vibi_Initialize
local n as byte
' should be called on startup
CALL Tubi_Stop ' make sure power is OFF
for n = 60 to 107 ' 96 is the note limit, but we have more timers on board.
CALL Vibi_Beat n, 20 ' zie proc. - this will be inaudible since we have no power yet
CALL Vibi_Damp n, 20
next n
CALL Vibi_Read_Port ' only read after a reset of the PIC
CALL Vibi_Start ' autostart
end
Vibi_Read_Port
IF RA4 = 1 then bit set (midichannel, 0) else bit reset (midichannel, 0)
IF RA5 = 1 then bit set (midichannel, 1) else bit reset (midichannel, 1)
IF RC4 = 1 then bit set (midichannel, 2) else bit reset (midichannel, 2)
IF RC5 = 1 then bit set (midichannel, 3) else bit reset (midichannel, 3)
end
Vibi_Start
' sends pincode to board: (switch on the high power supply)
' this proc. should be called on reception of midi controller 66 with param = %true
out dport, 251 ' pincode number
out aport, reg(3)
strobe
out aport, reg(2)
out dport, 251 ' required for start up of the basic stamps (BS2)
strobe (RC3 high to low and back to high for 1 microsecond)
end
Vibi_Stop
' sends inverted pincode to board:(high power supply switched off
' not implemented on Vibi hardware yet
out dport, 5 ' inverted pincode
out aport, reg(2) ' port nr.3 - ext1port
strobe
out aport, reg(3)
strobe '(RC3 high to low and back to high for 1 microsecond)
end
Vibi_Beat (note as byte, velo as byte)
' this is the 8 bit msb only code for the timer chips
' notes 60-96 = normal pitches
local cw as dword
local wvelo as dword
if velo = 0 then exit function
if note < 60 then exit function
if note > 107 then exit function
note = note - 60
wvelo = 3584 + ((velo * velo) /2) ' kwadratisch 3584-10648
velo = HIBYT(wvelo)
cw = n MOD 3 ' control word , here 0,1,2
shift left cw, 6 ' put bits in the right place for the timer chip: D7 en D6 = select timer
bit set cw,5 ' set bit 5, so be use msb only. (setting bit 4 would be lsb only)
' velo:
' in 256 microsecond increments
' thus the range is 0.256ms to 32 ms for 1-127 velo.
out aport, reg(1) ' 2 bitlines velodatabus
out dport, 3 ' set both lines high, write a command to the 82C54
strobe
out aport, reg(0) ' databus 8 bit
out dport, cw ' write program byte to the bus
strobe
out aport, reg(5) ' cause strobe on the 74154's
out dport, note \ 3 ' chip number
strobe
out aport, reg(7) '
strobe
' now send the required data to the timer:
out aport, reg(1)
out dport, note MOD 3 ' 0=timer0 1=timer1 2=timer2 3=control
strobe
out dport, note \ 3 ' prepare chip selector
out aport, reg(5)
strobe
' send 1 byte of timer data
out aport, reg(0)
out dport, velo
strobe
out aport, reg(7) ' generate a strobe
strobe ' now the counter should be counting...
end
Vibi_Damp (note as byte, velo as byte)
' should be called on reception of note off + release.
' notes 60-96 = normal pitches
' here there is less of a benefit in using 16 bit.
local cw as dword
local wvelo as dword
if velo = 0 then exit function ' no damping
if note < 60 then exit function
if note > 96 then exit function
note = note - 12 ' harware mapped op notes 48 - 84
wvelo = velo * velo ' kwadratisch
if wvelo < 3600 then wvelo = 3600 ' opgelet , andere scaling dan vibi_beat!!!
velo = HIBYT(wvelo)
cw = n MOD 3 ' control word , here 0,1,2
shift left cw, 6 ' put bits in the right place for the timer chip: D7 en D6 = select timer
bit set cw,5 ' set bit 5, so be use msb only. (setting bit 4 would be lsb only)
' velo:
' in 256 microsecond increments
' thus the range is 0.256ms to 32 ms for 1-127 velo.
out aport, reg(1) ' 2 bitlines velodatabus
out dport, 3 ' set both lines high, write a command to the 82C54
strobe
out aport, reg(0) ' databus 8 bit
out dport, cw ' write program byte to the bus
strobe
out aport, reg(5) ' cause strobe on the 74154's
out dport, note \ 3 ' chip number
strobe
out aport, reg(7) '
strobe
' now send the required data to the timer:
out aport, reg(1)
out dport, note MOD 3 ' 0=timer0 1=timer1 2=timer2 3=control
strobe
out dport, note \ 3 ' prepare chip selector
out aport, reg(5)
strobe
' send 1 byte of timer data
out aport, reg(0)
out dport, velo
strobe
out aport, reg(7) ' generate a strobe
strobe ' now the counter should be counting...
end function
Vibi_Motor (motornumber, speed)
if speed > 100 then speed = 100
select case motornumber
case 0
out dport, speed
out aport, reg(3) ' port 4 - ext.2 port
strobe
case 1
out dport, speed
out aport, reg(2)
strobe
case 2
out dport speed
out aport, reg(3)
strobe
out aport, reg(2)
strobe
end select
end function
Vibi_Beat_16bitcoding (note, velo)
local wvelo as dword
local cw as dword
' this did not work on the wintel platform...
IF note < 60 then exit function
if note > 107 then exit function
if isfalse velo then exit function
note = note - 60
'wvelo = 3584 + ((velo * velo) /2) ' kwadratisch 3600-11648
wvelo = 3584 + (velo * 100) ' lineair in 100microsec. stapjes 3584 tot 16284
cw = note MOD 3
shift left cw, 6
bit set cw, 4
bit set cw, 5
out aport, reg(1)
out dport, 3 ' command
strobe
out aport, reg(0)
out dport, cw
strobe
out aport, reg(5)
out dport, note \ 3 ' chip number - integer divide
strobe
out aport, reg(7)
strobe
out aport, reg(1)
out dport, note MOD 3
strobe
out aport, reg(5)
out dport, note \ 3
strobe
' now send lsb:
out aport, reg(0)
out dport, LOBYT(wvelo)
strobe
out aport, reg(7)
strobe
' then msb:
out aport, reg(0)
out dport, HIBYT(wvelo)
strobe
out aport, reg(7)
strobe
' lsb-msb send, timer should be counting...
end function
FUNCTION Vibi_Midi_Input ()
static init
static dampval
static dampmode ' 0 = use the damp value as set with the controller
' 1 = use note-off + release for damping control
static sustain ' 1 = no damping
if isfalse init then
'Initialisation of default values:
sustain = %False
dampmode = %False
damptim = 64
dampval = 80
init = %True
end if
if statusbyte = controller then
select case controller
case 20
Vibi_Motor, 0, value
case 21
Vibi_Motor, 1, value
case 22
Vibi_Motor, 2, value
case 23
dampval = value
case 24
if value then dampmode = %True else dampmode = %False
case 64 ' sustain pedal
if value the sustain = %true else sustain = %False
case 66
CALL Vibi_On ' quite impossible with vibi hardware...
case 123
sustain = %False
dampmode = %False
dampval = 80
Call Vibi_All_Off
case 127
' reset PIC, reread receive channel
end select
end if
if statusbyte = note-on then
select case note
case > 59
select case velo
case %False
if isfalse sustain then
if dampval then
if dampmode then
CALL Vibi_Damp noot, dampval
else
' niks - note-off release should be used.
end if
end if
else
' no damping at all !!!
end if
case else
CALL Vibi_Beat noot, velo
end select
case 12 to 48 ' play with the dampers as beaters!
note = note + 48
CALL Vibi_Damp noot, velo
end select
end if
if statusbyte = note-off then
select case value
case %False
' no damping
case else
select case dampmode
case %False
CALL Vibi_Damp, noot, value
case %True
IF dampval then
CALL Vibi_Damp, noot, dampval ' improper coding by user
end if
end select
end select
end if
end function
Midi implementation:
<Vibi> should listen to Note On + Velo commands for notes 60-96.
<Vibi> should listen to Note Off + Velo commands for notes 60-96 for the dampers.
<Vibi> listens to following controllers:
20 ' motor 0
21 ' motor 1
22 ' both motors
23 ' set damping force
24 ' set damping mode
64 ' sustain - sets sustain mode
66 ' power ON
123 ' all notes off / resets controllers
127 ' pic reset
Vibi should listen to the channel set with the dip switches (0-15).
The normal channel-setting for Vibi is 10.
The pincode command can be implemented as a binary midi controller >= 66 (on/off).
The user should send this controller in order to enable Vibi.