* Filename : SCI.ASM * Programmer : Michael Hattermann * Date : February 4, 2002 * Version : 1.0 * Description : This file contains SCI communication * functions for input and output of * data. The following functions are * available: * * WAIT_TC - wait for transmit complete * SET_BAUD - change the baud rate * TX_ON - turn transmitter on * TX_OFF - turn transmitter off * RX_ON - turn receiver on * RX_OFF - turn receiver off * RX_INT_ON - turn receiver interrupts on * RX_INT_OFF - turn receiver interrupts off * OUTCHAR - prints character to screen * OUTSTR - prints string to screen * INCHARWAIT - waits for character input * INCHAR - get character input if any * OUTNUM - prints number to screen * NIBTOCHAR - prints nibble to screen * OUTADDR - prints 16-bit num to screen * INITSCI - turns on SCI for 9600 baud * * *#define __DEBUGSCI_ 1 #include "hc12.asm" * ************************************************************ * SCI Equates ************************************************************ * ****Baud rate equates**** BAUD19200 EQU 0 BAUD14400 EQU 2 BAUD9600 EQU 4 BAUD4800 EQU 6 BAUD2400 EQU 8 BAUD1200 EQU 10 BAUD600 EQU 12 BAUD300 EQU 14 ****ASCII character equates**** EOS EQU $04 ; User-defined End Of String (EOS) character CR EQU $0D ; Carriage Return Character LF EQU $0A ; Line Feed Character ESC EQU $1B ; ESC character * ************************************************************ * SCI Test Program ************************************************************ * #ifdef __DEBUGSCI_ ORG $0900 HELLO DC.B 'Hello world!!!' NEWLINE DC.B CR,LF ; Newline string DC.B EOS PRESSKEY DC.B 'Press any key to continue' DC.B CR,LF,EOS CHANGETO DC.B 'Change baud rate to: ' DC.B EOS PROMPT DC.B 'Start typing...' DC.B CR,LF,EOS TEST LDAA #$00 ; turn off COP watchdog timer STAA COPCTL LDS #$0bff ; init the stack pointer JSR INITSCI ; init SCI system LDX #HELLO ; print "hello world" JSR OUTSTR ; LDX #CHANGETO ; print change baud message JSR OUTSTR ; LDX #$1200 ; print new baud rate JSR OUTADDR ; LDX #NEWLINE ; print new line JSR OUTSTR ; LDX #PRESSKEY ; print "press any key" JSR OUTSTR ; JSR INCHARWAIT ; wait for character LDAA #BAUD1200 ; change baud rate JSR SET_BAUD ; LDX #HELLO ; print "hello world" JSR OUTSTR ; LDX #$1234 ; test print address JSR OUTADDR ; LDX #PROMPT ; print prompt JSR OUTSTR ; HERE JSR INCHARWAIT ; get character JSR OUTCHAR ; echo to screen BRA HERE ; end of program #endif * ************************************************************ * Constant Definitions ************************************************************ * BAUDTBL DC.W 13 ; (0) BAUD rate = 19200 DC.W 17 ; (1) BAUD rate = 14400 DC.W 26 ; (2) BAUD rate = 9600 DC.W 52 ; (3) BAUD rate = 4800 DC.W 104 ; (4) BAUD rate = 2400 DC.W 208 ; (5) BAUD rate = 1200 DC.W 417 ; (6) BAUD rate = 600 DC.W 833 ; (7) BAUD rate = 300 * ******************************************************************************* * SUBROUTINE - WAIT_TC * Description: Waits for the current transmit operation to complete (polls the * TC flag in SCI status register 1) * Input : None. * Output : None. * Destroys : None. * Calls : None. ******************************************************************************* * WAIT_TC BRCLR SC0SR1,BIT6,WAIT_TC ; wait until done sending RTS ; Return to caller * * ******************************************************************************* * SUBROUTINE - SET_BAUD * Description: Sets the baud rate to the rate specified in register A. Reg A * can only take on these predefined values: * BAUD19200 = BAUD rate 19200 * BAUD14400 = BAUD rate 14400 * BAUD9600 = BAUD rate 9600 * BAUD4800 = BAUD rate 4800 * BAUD2400 = BAUD rate 2400 * BAUD1200 = BAUD rate 1200 * BAUD600 = BAUD rate 600 * BAUD300 = BAUD rate 300 * * Input : New baud rate in reg A * Output : None. * Destroys : SC0BDH, SC0BDL. * Calls : None. ******************************************************************************* * SET_BAUD PSHX ; Preserve reg X LDX #BAUDTBL ; Load address of baud table LDX A,X ; Load baud rate from table STX SC0BD ; Set baud rate in register PULX ; Restore reg X RTS ; Return to caller * ******************************************************************************* * SUBROUTINE - TX_ON, TX_OFF * Description: Enables transmitter, disables transmitter * Input : None. * Output : None. * Destroys : SC0CR2. * Calls : None. ******************************************************************************* * TX_ON BSET SC0CR2,BIT3 ; turn on the transmitter RTS ; return to caller TX_OFF BCLR SC0CR2,BIT3 ; turn off the transmitter RTS ; return to caller * ******************************************************************************* * SUBROUTINE - RX_ON, RX_OFF,RX_INT_ON,RX_INT_OFF * Description: Enables receiver, disables receiver, enables receive interrupts, * disables receive interrupts * Input : None. * Output : None. * Destroys : SC0CR2. * Calls : None. ******************************************************************************* * RX_ON BSET SC0CR2,BIT2 ; turn on the receiver RTS ; return to caller RX_OFF BCLR SC0CR2,BIT2 ; turn off the receiver RTS ; return to caller RX_INT_ON BSET SC0CR2,BIT5 ; enable receiver interrupts RTS ; return to caller RX_INT_OFF BCLR SC0CR2,BIT5 ; disable receiver interrupts RTS ; return to caller * ************************************************************************ * SUBROUTINE - OUTCHAR * Description: Outputs the character in register A to the screen * Input : Data to be transmitted in register A. * Output : Transmits the data. * Destroys : None. * Calls : WAIT_TC ************************************************************************ * OUTCHAR JSR WAIT_TC ; wait until transmitter is idle STAA SC0DRL ; output character RTS ; Return from subtoutine * ************************************************************************ * SUBROUTINE - OUTSTR * Description: Outputs the string pointed to by X. String must be * terminated by EOS character. * Input : String to be output in reg X * Output : Transmits the string. * Destroys : None. * Calls : OUTCHAR ************************************************************************ * OUTSTR PSHA ; preserve reg A PSHX ; preserve reg X OUTSTR1 LDAA 1,X+ ; Get a character (put in reg A) CMPA #EOS ; Check if it's EOS BEQ OUTSTR2 ; Branch to Done if it's EOS JSR OUTCHAR ; Print the character BRA OUTSTR1 OUTSTR2 PULX ; restore reg X PULA ; restore reg A RTS ; Return from subtoutine * ************************************************************************ * SUBROUTINE - INCHARWAIT * Description: Waits for a character to be pressed and reads it into * reg A * Input : None * Output : Character pressed in reg. A * Destroys : A. * Calls : None ************************************************************************ * INCHARWAIT BRCLR SC0SR1,BIT5,INCHARWAIT ; wait until buffer full LDAA SC0DRL ; input character RTS ; Return from subroutine * ************************************************************************ * SUBROUTINE - INCHAR * Description: Checks to see if character recevied - if so returns the * character, if not returns 0 * Input : None * Output : Character pressed in reg A; 0 if none * Destroys : A. * Calls : None ************************************************************************ * INCHAR BRCLR SC0SR1,BIT5,INCHAR1 ; if there is no data, get out LDAA SC0DRL ; yes, read data INCHAR1 RTS ; return to caller * ************************************************************************ * SUBROUTINE - OUTNUM * Description: Outputs the number in register A to the screen * Input : Data to be transmitted in register A. * Output : Transmits the data. * Destroys : None. * Calls : NIBTOCHAR ************************************************************************ * OUTNUM PSHA ; preserve reg A PSHA ; preserve reg A ANDA #%11110000 ; get upper nibble LSRA ; shift it right to get the nibble LSRA LSRA LSRA JSR NIBTOCHAR ; change A and print it PULA ; restore reg A ANDA #%00001111 ; get lower nibble JSR NIBTOCHAR ; change A and print it PULA ; restore reg A RTS ; return to caller * ************************************************************************ * SUBROUTINE - NIBTOCHAR * Description: Converts lower nibble of A to ASCII and prints it * Input : Data to convert in A. * Output : Transmits the data. * Destroys : None. * Calls : OUTCHAR ************************************************************************ * NIBTOCHAR CMPA #9 ; is it greater than 9? BGT NIBTOCHAR1 ; if so, print a character ADDA #48 ; if not, print a number starting at 48 ASCII BRA NIBTOCHAR2 ; NIBTOCHAR1 ADDA #55 ; if so, print a letter starting at 55 = 65-10 NIBTOCHAR2 JSR OUTCHAR ; print it RTS * ************************************************************************ * SUBROUTINE - OUTADDR * Description: Outputs the number in reg X to the screen * Input : Data to print in X. * Output : Transmits the data. * Destroys : None. * Calls : OUTNUM ************************************************************************ * OUTADDR PSHD ; save reg D TFR X,D ; load X into D JSR OUTNUM ; prints whats in A -- MSB TBA ; B -> A JSR OUTNUM ; prints whats in B -- LSB PULD ; restore D RTS ; return to caller * ************************************************************************ * SUBROUTINE - INITSCI * Description: This subroutine initializes the BAUD rate to 9600 and * sets up the SCI port for 1 start bit, 8 data bits and * 1 stop bit. It also enables the transmitter and receiver * Input : None. * Output : Initializes SCI. * Destroys : None. * Calls : SET_BAUD,TX_ON,RX_ON ************************************************************************ * INITSCI PSHA ; save reg A LDAA #BAUD9600 ; set the baud rate to 9600 JSR SET_BAUD ; JSR TX_ON ; turn on the transmitter JSR RX_ON ; turn on the receiver PULA ; restore reg A RTS ; Return from subtoutine * ************************************************************************