;********************************************************************** ;* Module : SCI_INT.MOD ;* Programmer: Tony Papadimitriou ;* Purpose : Interrupt-driven SCI RX and TX OS-called routines ;* Language : MC68HC11 (ASM11 v1.83+) ;* Status : FREEWARE, Copyright (c) 1999 by Tony Papadimitriou ;* Segments : RAM : Variables ;* : ROM : Code ;* : SEG9 : OS definitions (this allows adding more functions) ;* : VECTORS: SCI vector ;* Subsystems: Makes use of SCI interrupts ;* History : 99.11.12 v1.00 Original (Started on 99.11.12) ;* : 99.11.12 v1.01 Added fGetChar ;* : 99.11.27 v1.02 Added fGetPossibleChar (doesn't wait for char) ;********************************************************************** #ifmain ;---------- allows for separate compilation ------------------- #LISTOFF #INCLUDE 811E2.INC #INCLUDE COMMON.INC #INCLUDE OS11/OSERRORS.INC #LISTON #SEG9 ORG $FF00 #endif #RAM ?MAXBUF EQU 16 ;RX and TX buffer lengths ; zero RX.index or TX.index indicates empty buffer ?RX.index rmb 1 ;offset into RX buffer ?RX.buffer rmb ?MAXBUF ;buffer for received characters ?TX.index rmb 1 ;offset into TX buffer ?TX.buffer rmb ?MAXBUF ;buffer for characters to transmit #SEG9 #ifndef OSCommands OSCommands equ * #endif fError equ *-OSCommands/2 ;Print error message on the SCI dw ?Error fErrorJump equ *-OSCommands/2 ;fError and jump to address dw ?ErrorJump fUsrErrorJump equ *-OSCommands/2 ;Like fErrorJump with User error dw ?UsrErrorJump fSetBAUD equ *-OSCommands/2 ;Set SCI bps ("baud") rate dw ?SetBAUD fPrint equ *-OSCommands/2 ;Print the following FCS string dw ?Print fGetPossibleChar equ *-OSCommands/2 ;Read SCI char is present into RegA dw ?GetPossibleChar fGetChar equ *-OSCommands/2 ;Read SCI char into RegA dw ?GetChar fPutChar equ *-OSCommands/2 ;Write RegA character to the SCI dw ?PutChar fWrite equ *-OSCommands/2 ;Write a "Pascal" string to SCI dw ?Write fWriteln equ *-OSCommands/2 ;fWrite followed by CR,LF pair dw ?Writeln fNewLine equ *-OSCommands/2 ;Send a CR,LF pair to the SCI dw ?NewLine fWriteZ equ *-OSCommands/2 ;Write an ASCIZ string to SCI dw ?WriteZ fWritelnZ equ *-OSCommands/2 ;fWriteZ followed by CR,LF pair dw ?WritelnZ #PAGE ;Operating System routines expanded ********************************************************************** * Operating System routines expanded * ********************************************************************** #ROM ; Purpose: Print error message on the SCI and jump to address in X ; Input : B holds error code ; : X holds address to jump to after printing error ; Output : None ?ErrorJump ldx X_,y ;get address to jump to stx PC_,y ;and use it as return PC ; fall through to fError (do not change fError's location) ; Purpose: Print error message on the SCI ; Input : B holds error code ; Output : None ; Note(s): Uses fPrint, fWritelnZ ?Error ldb B_,y ;get error code beq ?Error.Exit ;not an error decb ;make error zero-based clra ;we'll be using D lsld ;multiply by size of table entries cmpd #?Error.Size ;is it within our table size bhs ?Error.Exit ;invalid error code, get out addd #?Error.Table ;point to beginning of table xgdx ;put pointer in X ldx ,x ;get pointer to error msg os fPrint ;print standard error header fcs CR,LF,'OS ERROR(' os fWritelnZ ?Error.Exit clc rts ?Error.Table dw ?Error.1 dw ?Error.2 dw ?Error.3 dw ?Error.4 dw ?Error.5 dw ?Error.6 ?Error.Size equ *-?Error.Table/2 ?Error.1 fcs '1): Other' ?Error.2 fcs '2): Invalid Call' ?Error.3 fcs '3): Bad Parameter' ?Error.4 fcs '4): Failed' ?Error.5 fcs '5): Out Of Range' ?Error.6 fcs '6): Not found' ; Purpose: Print user error message on the SCI ; Input : Y -> user error message ; : X holds address to jump to after printing error ; Output : None ; Note(s): Uses fPrint, fWritelnZ ?UsrErrorJump os fPrint ;print standard error header fcs CR,LF,'ERROR: ' ldx Y_,y ;get pointer to error msg os fWritelnZ ldx X_,y ;set user address stx PC_,y ;..to return to clc rts ; Purpose: Set SCI BAUD rate to one of the following values (in A_,y) ; 3(00), 12(00), 24(00), 48(00), 96(00), 125(000) ; (use number outside parentheses for corresponding baud rate) ; Input : RegA = Baud Rate (without trailing zeros) ; Note(s): Assumes 8MHz XTAL (2MHz E-Clock) ?BPS_Table db 3,$35 ;300 bps (user value, MCU value) db 12,$33 ;1200 bps db 24,$34 ;2400 bps db 48,$31 ;4800 bps db 96,$30 ;9600 bps db 125,$00 ;125000 bps ?BPS_Table.Entries equ *-?BPS_Table/2 ;number of entries in table ?SetBAUD lda A_,y ;get user bps rate value ldx #?BPS_Table ;point to table with MCU bps rates ldb #?BPS_Table.Entries ;get number of entries to test ?SetBAUD.BpsLoop cmpa ,x ;is it the same as in table? beq ?SetBAUD.SetBAUD ;go set it inx:2 ;point to next entry decb ;are we done with all entries? bne ?SetBAUD.BpsLoop ;if not, try again ?SetBAUD.Error ldb #errBadParm ;not found, return error code in B sec rts ?SetBAUD.SetBaud lda 1,x ;get MCU bps rate value clr SCCR2 ;disable SCI while changing BAUD sta BAUD clr SCCR1 lda #%00101100 ;Interrupt RX and TX mode sta SCCR2 ; Clear the buffer to be used for transmission/receipt of data ldx #?RX.index ;get pointer to beginning of vars ldb #?MAXBUF+1*2 ;get length for both buffers and indices ?SetBAUD.Loop clr ,x ;clear buffer inx ;advance pointer decb ;one less to go bne ?SetBAUD.Loop ;repeat until done clc ;no error exit rts ; Purpose: Print constant ASCIZ string following OS instruction (with FCS) ; Parms : None ?Print ldx PC_,y ;get address following OS ?Print.Loop lda ,x ;get character to print beq ?Print.Exit ;at the end of ASCIZ string, exit bsr ?PutChar.Local ;send the character to SCI inx ;point to next character bne ?Print.Loop ;avoids infinite loops ?Print.Exit inx ;point after NUL stx PC_,y ;..to use as return address clc ;no errors rts ; Purpose: Read SCI char, is present, into RegA ; Output : A holds character if Carry Clear ; : Carry set if character not available ?GetPossibleChar ldx #?RX.index sei jsr ?DeQ brset CCR_,y,I.,?GetPChar.NoInt cli ?GetPChar.NoInt bcs ?GetPChar.Zero ;check if zero ?GetPChar.OK sta A_,y clc ;never an error from here rts ?GetPChar.Zero tsta bne ?GetPChar.OK ;other it was last char ldb B_,y ;avoid destroying original B sec rts ; Purpose: Read SCI char into RegA ; Output : A holds character ?GetChar ldx #?RX.index sei bsr ?DeQ brset CCR_,y,I.,?GetChar.NoInt cli ?GetChar.NoInt bcs ?GetChar.Zero ;check if zero ?GetChar.OK sta A_,y clc ;never an error from here rts ?GetChar.Zero tsta beq ?GetChar ;if zero, wait for char bra ?GetChar.OK ;other it was last char ; Purpose: Write RegA character to the SCI ; Input : A holds character ?PutChar lda A_,y ?PutChar.Local pshx ldx #?TX.index ;point to TX buffer ?PutChar.Loop sei bsr ?EnQ ;attempt to enqueue char brset CCR_,y,I.,?PutChar.NoInt cli ?PutChar.NoInt bcs ?PutChar.Loop ;wait if not ready yet bsr ?TXEnable ;now, tell TCs can start working again pulx clc ;never an error from here rts ; Purpose: Write (send) a string to the SCI ; Input : X->buffer of Pascal-like string, ie., LengthByte,Char1,Char2,... ; Note(s): buffer should not be used for incoming chars, for it will be ; messed up. ?Write ldx X_,y ldb ,x ;get length of string beq ?Write.NoError ;if 0, nothing to send ?Write.Loop inx ;point to data lda ,x bsr ?PutChar.Local decb bne ?Write.Loop ?Write.NoError clc rts ; Purpose: Writeln (send) a string to the SCI followed by a CR,LF pair ; Input : X->buffer of Pascal-like string, ie., LengthByte,Char1,Char2,... ?Writeln bsr ?Write ;do regular fWrite bcs ?Writeln.Exit ;on failure, exit ; Purpose: Advance a line sending a CR,LF pair to the SCI ?NewLine lda #CR ;send a CR bsr ?PutChar.Local lda #LF ;send a LF bsr ?PutChar.Local clc ?Writeln.Exit rts ; Purpose: Write (send) a string to the SCI ; Input : X->ASCIZ string, ie., Char1,Char2,...,0 ; Note(s): buffer should not be used for incoming chars, for it will be ; messed up. ?WriteZ ldx X_,y ?WriteZ.Loop lda ,x beq ?WriteZ.NoError bsr ?PutChar.Local inx bne ?WriteZ.Loop ;avoids infinite loops ldb #errOutOfRange ;on memory wrap-around sec rts ?WriteZ.NoError clc rts ; Purpose: Writeln (send) a string to the SCI followed by a CR,LF pair ; Input : X->ASCIZ string, ie., Char1,Char2,...,0 ?WritelnZ bsr ?WriteZ ;do regular fWriteZ bcs ?Writeln.Exit ;on failure, exit bra ?NewLine ; EnQueue character in RegA to buffer pointed by X (RX.buffer or TX.buffer) ?EnQ pshb ldb ,x ;B := index incb ;index := index + 1 cmpb #?MAXBUF ;if index > ?MAXBUF then bhi ?Q.Error ; buffer full, exit stb ,x ;save updated index pshx abx ;point to buffer[index] sta ,x ;and save character pulx pulb clc rts ?Q.Error pulb ;common for ?EnQ and ?DeQ ?Q.Error1 sec rts ; DeQueue in RegA a character from buffer pointed by X (RX.index or TX.index) ?DeQ clra ;in case of error, A := NUL tst ,x ;if index = 0 then beq ?Q.Error1 ; exit with error lda 1,x ;A := buffer[1] (always return the first char) ?Q.Shrink pshx pshd ldb ,x ;get new length dec ,x ;decrement buffer length ?Q.Shrink.Loop decb beq ?Q.Shrink.Exit lda 2,x ;get next character sta 1,x ;into current character inx bra ?Q.Shrink.Loop ?Q.Shrink.Exit puld pulx tst ,x ;if new index = 0 then beq ?Q.Error1 ; exit with error clc rts ; Enable TX interrupts ?TXEnable psha lda SCCR2 ora #TDRF. sta SCCR2 pula rts ; SCI-related interrupt requests come here SCI_Handler lda SCSR ;get status to determine cause of interrupt psha ;save it for later bita #$20 ;Anything received? beq SCI_Transmit ;No, check TC flag lda SCDR ;get received character ldx #?RX.index bsr ?EnQ ;put character in RX queue bcs SCI_Exit ;if save not possible, exit SCI_Transmit pula ;restore SCSR status in A bita #TDRF. ;SCDR empty? beq SCI_Exit1 ;no, get out ldx #?TX.index ;point to string bsr ?DeQ ;get a character from TX queue bcc SCI_Exit2 ;not done yet, leave TC ints active tsta ;if A <> 0, send then exit beq SCI_DisableTX sta SCDR ;send it (clearing TC flag) SCI_DisableTX lda SCCR2 ;on empty queue... anda #NOT^TDRF. sta SCCR2 ;terminate further ints SCI_Exit1 rti ;exit without stack adjustment SCI_Exit2 sta SCDR ;send it (clearing TC flag) rti SCI_Exit ins ;adjust the stack for saved SCSR rti ;then exit #ifmain #include OS11/DISPATCH.MOD #endif #VECTORS ?vectors equ * org $FFD6 dw SCI_Handler org ?vectors #ROM end