' *******************************************************************
' * Program : PWM8254.BAS     Version : 1.1  -  06 Setptember 1999  *
' * Compiler: BASCOM 8051     (IDE V.1.0.0.16, LIB V.1.10)          *
' * Firm:     Grifo(r)      Via Dell'Artigiano 8/6                  *
' *                       40016 San Giorgio di Piano                *
' *                Tel. +39-051-892052  Fax +39-051-893661          *
' * http://www.grifo.com    http://www.grifo.it                     *
' * sales@grifo.it          tech@grifo.it          grifo@grifo.it   *
' *                                                                 *
' * Written by:    Graziano Gaiba                                   *
' *******************************************************************
'
' Program designed to work with BASCOM 8051 and a GPC(r) F2 board
' connected to an EMI 01 board.
' This program drives the two PWM outputs, avaiable on the EMI 01 board,
' capable to generate a tension between -10 and +10 V.
'
'************************* Compiler Directives  *******************************
'
$romstart = &H8050                             ' Start address of machine code
$ramstart = &HD000                             ' Start address of data area
$ramsize = &H2800                              ' 10k of data area
$crystal = 11059200                            ' Clock of microcontroller
$baud = 9600                                   ' RS-232 baud rate
$large                                         ' 16 bit addressing mode
'
'************************* Variables Declaration ******************************
'
Dim V As Word , S As Single , C As String * 1       ' Variabili di uso generico
Dim Nimp As Word                               ' Numero impulsi per generare Vout
Dim Indstat As Word , Indcnt2 As Word          ' Indirizzi registri 8253
Dim Cmdw2 As Byte                              ' Parola di comando per 8253
'
'***************************** Main Program ***********************************
'
Waitms 1                                       ' Delay for signals settling


Print Chr(12)                                  ' Clears the screen
Print "PLEASE SELECT WHICH IC 8254 TO USE (A or B) " ;
C = Waitkey                                    ' Waits for a key
Print C                                        ' Prints it
If C = "a" Then Goto Selection_a Else Goto Selection_b
                                               ' If the key is 'a'
Selection_a:                                   ' Use IC 8254 A
Indstat = &HFA43                               ' Assign address 8254 A status register
Indcnt2 = &HFA42                               ' Assign address counter 2 A data register
Goto Continue                                  ' Countinues

Selection_b:                                   ' Use IC 8254 B
Indstat = &HFA83                               ' Assign address 8254 B status register
Indcnt2 = &HFA82                               ' Assign address counter 2 B data register

Continue:                                      '                                      REM    endif
Cmdw2 = &HB2                                   ' Parola di comando per contatore 2: modo 1
Out Indstat , Cmdw2                            ' Inizializzazione contatore 2

Print : Print                                  ' Spacing
Print "PROGRAM FOR GENERATING A CONTINUOUS VOLTAGE"
Print "SELECTABLE BETWEEN -10V AND +10V, BY A PWM SIGNAL"

Repeat:                                        ' Repeat forever
Print : Print : Print :                        ' Spacing
Print "PLEASE INSERT A VALUE BETWEEN -10 AND +10"
Input S                                        ' Read the requested output
                                               ' Voltage value
' Calculates the number of impulses to send
'Nimp = ((s + 10.0) * 204.75)

If S = -10.0 Then
   Nimp = 1
Else
   S = S + 10.0
   S = S * 204.75
   Nimp = S
End If

Print "Number of Impulses = " ; Nimp           ' Prints the number of impulses to send

V = Low(nimp)                                  ' Low byte of impulses number
Print "Low byte of number of impulses = " ; V       ' Print it
Out Indcnt2 , Low(nimp)                        ' Print it
V = High(nimp)                                 ' High byte of impulses number
Print "High byte of number of impulses = " ; V       ' Print it
Out Indcnt2 , High(nimp)                       ' Print it
Goto Repeat                                    ' Repeat forever

End
'
'******************************** Program End ********************************
'