PIC16 Assembly
;
; Title: Asynchronous Serial Communication (* = See Datasheet)
; Author: Russell Carter
; Date: 10/99
;
List P=16F84,F=inhx8m
;
;===========Register Files=======================================================
;
indf equ 00
tmr0 equ 01
pcl equ 02
status equ 03
fsr equ 04
porta equ 05
portb equ 06
eedata equ 08
eeadr equ 09
pclath equ 0A
intcon equ 0B
option_reg equ 81
trisa equ 85 ; A "1" sets the relevant port bit as input
trisb equ 86 ; A "0" sets the relevant port bit as output
eecon1 equ 88
eecon2 equ 89
;
;===========Status Bits==========================================================
;
irp equ 07 ; Not Used
rp1 equ 06 ; Not Used
rp0 equ 05 ; 0 = Bank0, 1 = Bank1
not_to equ 04 ; WDT Time-out Bit*
not_pd equ 03 ; Power Down Bit*
z equ 02 ; 1 = Result is 0
dc equ 01 ; Digit Carry/Not-Borrow*
c equ 00 ; 1 = Carry-out from MSB
;
;===========Intcon Bits==========================================================
;
gie equ 07 ; 0 = Disables all interrupts
eeie equ 06 ; 1 = Enables EE Write complete int
t0ie equ 05 ; 1 = Enables TMR0 int
inte equ 04 ; 1 = Enables RB0/INT int
rbie equ 03 ; 1 = Enables RB port change int
t0if equ 02 ; 1 = TMR0 has overflowed
intf equ 01 ; 1 = RB0/INT int occured
rbif equ 00 ; 1 = An RB port pin changed state
;
;===========Option_Reg Bits======================================================
;
not_rbpu equ 07 ; 0 = PortB Pull-ups enabled
intedg equ 06 ; 1 = Int. on rising edge
tocs equ 05 ; TMR0 Clk 1 = External: T0CKI
t0se equ 04 ; 1 = Inc on falling edge of T0CKI
psa equ 03 ; 1 = Prescaler on WDT, 0 = Psa on TMR0
ps2 equ 02 ; Prescaler rate select bits*
ps1 equ 01 ; Prescaler rate select bits*
ps0 equ 00 ; Prescaler rate select bits*
;
;===========Eecon1 Bits==========================================================
;
eeif equ 04 ; 1 = Write op. complete (must be cleared)
wrerr equ 03 ; 1 = Write op. terminated prematurely
wren equ 02 ; 1 = Allows write cycles
wr equ 01 ; 1 = Initiate write (clears automatically)
rd equ 00 ; 1 = Initiate EEPROM read (clears auto.)
;
;===========Custom Defined Registers (68)========================================
;
; Usable range: 0Ch to 4Fh
;
t_status equ 0C ; Temp storage of Status reg
tx equ 0D ; Transmit Reg
rx equ 0E ; Recieve Reg
count equ 0F ; Bit Counter
flags equ 10 ; Flags reg
rx_buffer equ 11 ; Recieve buffers
del equ 17 ; Delay reg
;
;===========Custom Bits==========================================================
;
rip equ 01 ; Recieve in progress bit (Flags)
tip equ 02 ; Transmit in progress bit (Flags)
rxc equ 03 ; Recieve complete bit (Flags)
txc equ 04 ; Transmit complete (Flags)
fail equ 05 ; Recieve failed bit (Flags)
r equ 00 ; Recieve bit (PortA)
t equ 01 ; Transmit bit (PortA)
cts equ 02 ; Clear to send bit
;===========Information==========================================================
;
; Data format: Binary b'MSB...LSB', (Bit7...Bit0)
; Hex 0x00
; Decimal .000
;
;===========Beginning of Program=================================================
;
; Configuration: Half Duplex
; 1 Stop bit
; No Parity
;
org 0
goto init ; Start Vector
nop
nop
nop
goto service_int ; Interrupt Vector
init
clrf flags
clrf rx
clrf tx
clrf intcon
clrf porta
clrf portb
bsf port a,t ; Puts the Transmit Line in the idle state
bsf intc on,t0ie
bsf stat us,rp0 ; Ports are configured as inputs at power-up
bcf opti on_reg,tocs ; TMR0 = Internal clock
movlw b'00000001'
movwf trisa
movlw b'00000000'
movwf trisb
bcf stat us,rp0
clrf tmr0
main
call rx_enable ; Main program: wait to recieve byte, output
check1 ; to LED's and transmit byte back to PC.
btfss flags,rxc
goto check1
bcf flag s,rxc
call rx_disable
movf rx_buffer,0
movwf portb
movwf tx
clrf rx_buffer
call init_transmit
check2
btfss flags,txc
goto check2
bcf intc on,gie ; Always disable int after a txc flag!
bcf flag s,txc
clrf tx
goto main
service_int ; Test for conditions to determine
movlw .210 ; program banch
movwf tmr0
btfsc flags,rip
goto recieve
btfsc flags,tip
goto transmit
btfss porta,r
goto init_recieve
bcf intcon,t0if
retfie
rx_enable
bsf intcon,gie ; Init rx & set CTS line
bsf porta,cts
movlw .217
movwf tmr0
return
rx_disable
bcf porta,cts ; Disable rx & clear CTS line
bcf intcon,gie
return
init_recieve
bsf flags,rip
movlw .144
movwf tmr0
movlw .9
movwf count
bcf intcon,t0if
retfie
init_transmit
movlw .10
movwf count
bsf status,c
bsf flags,tip
bcf porta,t ; Beginning of start bit
movlw .170
movwf tmr0
bcf intcon,t0if
bsf intcon,gie
return
recieve
decf count
btfsc status,z
goto end_rx
btfsc porta,r
bsf rx,0
rrf rx ; Addlw, Addwf, Sublw, Subwf affect the carry
movlw .170
movwf tmr0
bcf intcon,t0if
retfie
transmit
decf count
btfsc status,z
goto end_tx
btfss tx,0
bcf porta,t
btfsc tx,0
bsf porta,t
rrf tx
movlw .173
movwf tmr0
bcf intcon,t0if
retfie
end_rx
rrf rx
btfss porta,r
bsf flags,fail
movf rx,0
btfss flags,fail
movwf rx_buffer
bsf flags,rxc
bcf flags,rip
clrf rx
movlw .223
movwf tmr0
movlw .9
movwf count
bcf status,c
bcf intcon,t0if
retfie
end_tx
bsf porta,t
bsf flags,txc
bcf flags,tip
bcf status,c
bcf intcon,t0if
retfie
;
end
;_______________________________________________________________________________Expand
Visual Basic 6.0
Private Sub bit_Click(Index As Integer)
Dim Byte1
Dim Decml
Dim Charact
For N = 7 To 0 Step -1
Byte1 = Byte1 & bit(N).Value
Next N
Decml = Bin2Dec(Byte1)
Charact = Chr(Decml)
Com.Output = Charact
End Sub
Private Sub cmdAuto_Click()
Dim N
For N = 1 To 255
txtCount.Text = N
txt1.Text = txtCount.Text
txt2.Text = Chr(txt1.Text)
Com.Output = txt2.Text
txt3.Text = (Dec2Bin(txt1.Text))
Duration = Timer + 0.01
Do Until Timer > Duration
Wait = DoEvents()
Loop
txt5.Text = Com.Input
If txt5.Text > "" Then txt4.Text = Asc(txt5.Text)
If txt5.Text > "" Then txt6.Text = (Dec2Bin(txt4.Text))
Duration = Timer + 0.01
Do Until Timer > Duration
Wait = DoEvents()
Loop
If txtCount.Text = 0 Then Exit Sub
Next N
End Sub
Private Sub cmdDown_Click()
Dim N
txt1.Text = txtCount.Text
txt2.Text = Chr(txt1.Text)
Com.Output = txt2.Text
txt3.Text = (Dec2Bin(txt1.Text))
Duration = Timer + 0.05
Do Until Timer > Duration
Wait = DoEvents()
Loop
txt5.Text = Com.Input
If txt5.Text > "" Then txt4.Text = Asc(txt5.Text)
If txt5.Text > "" Then txt6.Text = (Dec2Bin(txt4.Text))
If txtCount.Text > 0 Then
N = txtCount.Text
N = N - 1
txtCount.Text = N
Else
Exit Sub
End If
End Sub
Private Sub cmdRes_Click()
txtCount.Text = 0
txt1.Text = ""
txt2.Text = ""
txt3.Text = ""
txt4.Text = ""
txt5.Text = ""
txt6.Text = ""
End Sub
Private Sub cmdUp_Click()
Dim N
txt1.Text = txtCount.Text
txt2.Text = Chr(txt1.Text)
Com.Output = txt2.Text
txt3.Text = (Dec2Bin(txt1.Text))
Duration = Timer + 0.05
Do Until Timer > Duration
Wait = DoEvents()
Loop
txt5.Text = Com.Input
If txt5.Text > "" Then txt4.Text = Asc(txt5.Text)
If txt5.Text > "" Then txt6.Text = (Dec2Bin(txt4.Text))
If txtCount.Text < 255 Then
N = txtCount.Text
N = N + 1
txtCount.Text = N
Else
Exit Sub
End If
End Sub
Private Sub Command1_Click()
Form2.Show
Form1.Hide
End Sub
Private Sub Form_Load()
Com.PortOpen = True
statBar.SimpleText = "Com Port: " & Com.CommPort
End Sub
Private Sub Option1_Click()
Com.PortOpen = False
Com.CommPort = 1
Com.PortOpen = True
statBar.SimpleText = "Com Port: " & Com.CommPort
End Sub
Private Sub Option2_Click()
Com.PortOpen = False
Com.CommPort = 2
Com.PortOpen = True
statBar.SimpleText = "Com Port: " & Com.CommPort
End SubExpand
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