eh, have a looksee anyway.
Might be useful, then again, it might not be. but its published now for your eyes to see.
Alot of this could be optimized and cleaned up, such as the 2 dedicated I/O pins for active pulldowns really arnt necessary, but it was my first attempt at working a protocol, and it works. lol.
Remember now, the original intent which was never finished, was using a PS/2 based mouse on a Mac 128/512/Plus so it was provisioned to emulate the square wave encoder signals but i never got that far, so debugging routines are in there, for example LEDs are used to indicate the mouse movement, and positioning information.
Might be useful, then again, it might not be. but its published now for your eyes to see.
Alot of this could be optimized and cleaned up, such as the 2 dedicated I/O pins for active pulldowns really arnt necessary, but it was my first attempt at working a protocol, and it works. lol.
Remember now, the original intent which was never finished, was using a PS/2 based mouse on a Mac 128/512/Plus so it was provisioned to emulate the square wave encoder signals but i never got that far, so debugging routines are in there, for example LEDs are used to indicate the mouse movement, and positioning information.
Code:
' *
' * Title : PS2.bas
' * Version : 1.0
' * Target : ATTiny2313
' * Author : techknight
' * Program code : BASCOM AVR
' * Hardware req. :
' * Description : IBM PS/2 Mouse to Macintosh Bus Mouse translator
' * TODO : Timeouts need added into PS/2 routines to prevent hangs
' *
' ***************************************************************************
'$regfile = "attiny2313.dat" ' use the Tiny2313
$regfile = "2313def.dat"
$crystal = 18432000 ' at 18.432mhz
'Configure the data direction registers for port D
'PD0 PS2 Data
'PD1 PS2 Clock
'PD2 PS2 Data PullDown NPN Transistor
'PD3 PS2 Clock Pulldown NPN Transistor
'PB0 Y interrupt
'PB1 Y direction
'PB2 X interrupt
'PB3 X direction
'PB4 Mouse Button 1
Disable Interrupts
Config Portd = Output
Config Portd.0 = Input
Config Portd.1 = Input
Config Portb = Output
Portd = 0 'turn all internal pullups OFF and outputs to 0
Portb = 0
Portd.3 = 1 'inhibit communication between any PS/2 device
Dim Temp As Byte
Dim Temp2 As Byte
Dim Count As Byte
Dim Index As Byte
Dim I As Byte
Dim Ps2 As Byte
Dim Parity As Byte
Dim Status As Byte
Dim Movex As Byte
Dim Movey As Byte
Dim Button As Byte
'PS2 data send/receive routines
Declare Sub Sendps2(byval A As Byte)
Declare Sub Recps2
Declare Sub Initmouse
'Main Loop
Call Initmouse
Do
Call Recps2
Status = Ps2
Call Recps2
Movex = Ps2
Call Recps2
Movey = Ps2
'Set mouse button
Portb.4 = Status.0
'Mouse has moved down
If Status.5 = 1 Then
Portb.1 = 1
End If
If Status.4 = 1 Then 'mouse has moved left
Portb.3 = 1
End If
If Movex > 0 And Movex < &H7F Then 'mouse has moved right
Portb.2 = 1
End If
If Movey > 0 And Movey < &H7F Then 'mouse has moved up
Portb.0 = 1
End If
If Status.7 = 1 Then
Portb.0 = 1
End If
If Status.6 = 1 Then
Portb.2 = 1
End If
Waitms 5
Portb = 0
'DEBUGGING ROUTINE... Flash out byte PS2 and HALT
'I = 0
'For I = 7 To 0 Step - 1
'Portb.1 = 1
'Portb.0 = Status.i
'Wait 1
'Portb.1 = 0
'Wait 1
'Next
Loop
'This subroutine prepares the PS/2 Slave device for a data transmission from the AVR Host...
'data byte in A is written to the slave device
Sub Sendps2(byval A As Byte)
Parity = 0
I = 0
Ps2 = 0
Count = 0
Temp2 = A
Portd.3 = 1 'pull clock low, inhibit communication
Waitus 100 'wait 100 microseconds
Portd.2 = 1 'pull the data line low
'Request to Send
Portd.3 = 0 'Release the clock line
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
Do
Shift Temp2 , Right
Temp = Sreg And 1
If Temp = 1 Then
Portd.2 = 0 'Release data line, pulls high
Parity = Parity + 1
Else
Portd.2 = 1 'pull data low
End If
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
I = I + 1
Loop Until I = 8
If Parity.0 = 0 Then
Portd.2 = 0 'if even parity, set data line high by turning off pulldown
Else
Portd.2 = 1 'otherwise its odd parity so set data line low turning on pulldown
End If
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
Portd.2 = 0 'release the data line
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
If Pind.0 = 1 Then 'If no ACK received, then we try it again 3 times
Portd.3 = 1 'inhibit communication and try resending again.
Goto Sendps2
Count = Count + 1
If Count = 3 Then
Ps2 = &HFF
Exit Sub
End If
End If
Do
Loop Until Pind.1 = 1 'wait for clock to go idle high
Waitus 50
Portd.3 = 1 'Inhibit communications after transmission
End Sub
'This subroutine recieves back any data that the PS/2 slave device may have in its buffer.
'Data and Clock lines get set to idle state and listen for any responses from the device
'Received data byte stored into variable PS2
Sub Recps2
Parity = 0
I = 0
Ps2 = 0
Portd.3 = 0 'release the clock and data line to idle = high
Portd.2 = 0 'Ready to Receive
Do
Loop Until Pind.1 = 0 'wait until clock transistion low
If Pind.2 = 1 Then Goto Recps2 'if data high, false start bit received, re-call routine
'Read in 8 data bits
Do
Rotate Ps2 , Right , 1 'Rotate the data bits by 1
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
If Pind.0 = 1 Then
Set Ps2.7
Parity = Parity + 1
Else
Reset Ps2.7
End If
I = I + 1
Loop Until I = 9 '0 is a state in this sense.
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
'parity bit is 0 on an odd number of 1's
'parity bit is 1 on an even number of 1's
'So, we test on the condition of bad parity.
'so if we had 3 1's, and parity bit is 1, packet is BAD.
'or vice-versa, even number of 1's and 0 parity bit.
'otherwise, packet recieved properly
If Parity.0 = 1 And Pind.0 = 1 Then
Portd.3 = 1 'inhibit communication forcing clock low
Call Sendps2(&Hfe) 'Call for Resend on bad parity and try again
Goto Recps2
Elseif Parity.0 = 0 And Pind.0 = 0 Then
Portd.3 = 1
Call Sendps2(&Hfe)
Goto Recps2
End If
Do
Loop Until Pind.1 = 1 'wait high/low transistion. data valid only on low transition
Do
Loop Until Pind.1 = 0
If Pind.0 = 0 Then 'stop bit is logical 1, if 0 then bad transmission try again..
Portd.3 = 1
Call Sendps2(&Hfe)
Goto Recps2
End If
'otherwise, if we pass all this crap above, then yay the PS/2 packet was received properly.
Portd.3 = 1 'Transmission recieved, inhibit communication to allow time for processing
End Sub
'This subroutine initializes a PS/2 mouse and puts it into data reporting mode.
'When in data reporting mode, any movment or action from the mouse, it will transmitt bytes
'back to host when lines are idle (logic high), otherwise it buffers until overflow, or lines release
Sub Initmouse
Index = 0
Ps2 = 0
Do
Call Sendps2(&Hff) 'Reset the mouse
Call Recps2 'Receive the ACK
If Ps2 = &HFA Then 'is ACK ok?
Call Recps2
If Ps2 = &HAA Then 'Self test passed?
Call Recps2
If Ps2 = &H00 Then 'is PS/2 device a valid mouse?
Call Sendps2(&Hf4) 'Enable data reporting streaming (sends data on mouse movement or action)
Call Recps2
If Ps2 = &HFA Then 'did mouse ACK the sent command?
Ps2 = 0
Exit Sub 'mouse initiliazation passed
End If
End If
End If
End If
Index = Index + 1
Loop Until Index = 3
Ps2 = &HFF 'mouse initialization failed
End Sub