; ******************************************************************************** ; Filename: picmrsrc.asm ; Date: Tuesday, November 12th, 2008 23:25 ; File Version: ; Author: Lawrence Foltzer ; Modified by: Mike Addlesee ; More comments added and removed some redundant instructions. ; Minor changes required to port code to the 16F87 from the 16F84. ; Memory was relocated and some register bank swapping added. ; Removed use of obsolete instructions. ; Added debug LEDs to RA0-3. ; Fixed problem with bank switching in interrupt. ; Improved cursor management. ; Increased the tick period to ~6ms. ; Prompt output of last char of a word. ; Corrections to dit and dah tables. ; Removed or commented out some debug code. ; Size: 372 bytes ; ******************************************************************************** list p=16F87 ; list directive to define processor #include ; processor specific variable definitions ; __CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _HS_OSC ; timing based on 1.12MHz RC oscillator configuration using 5.1Kohm + 100pf ; __CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _RC_OSC ; timing based on 1.12MHz RC oscillator configuration using 5.1Kohm + 100pf ;Program Configuration Register 1 __CONFIG _CONFIG1, _CP_OFF & _CCP1_RB3 & _DEBUG_OFF & _WRT_PROTECT_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_OFF & _PWRTE_ON & _WDT_OFF & _EXTRC_CLKOUT ;Program Configuration Register 2 __CONFIG _CONFIG2, _IESO_OFF & _FCMEN_OFF ;#define diagnostics 1 ; Set LCD diagnostics "on". ; ******************************************************************************** ; Application specific equates. E equ .4 ; LCD strobe control line. Executes a read or write. LCDR_W equ .5 ; LCD read/not-write control line. RS equ .6 ; LCD register select control line. code_in equ .7 ; PORTB,7 (also ICSPDATA and tone LED). busy equ .3 ; The most significant bit of the LCD's data bus, D7. FuncSet41 equ 0x2A ; Command to get the LCD controller's attention. ; Sets: 4bit LCD bus interface, 2 line display & 5x7 dot characters. FuncSet42 equ 0x28 ; Command to get the LCD controller into right mode. ; Sets: 4bit LCD bus interface, 2 line display & 5x7 dot characters. DisplayOn equ 0x0c ; Command to get the LCD controller to switch on the display. ; Sets: Display on & Cursor off. EntryMode equ 0x06 ; Command to get the LCD controller to set the entry mode. ; Sets: Increment, but the display is not shifted. InitDdRam equ 0x2F ; Command to get the LCD controller to initialise the displays RAM. ; Sets: 4bit LCD bus interface, , 2 line display & 5x10 dot characters. lcdLine1Cmd equ .128 + .0 ; The starting position on the LCD for decoded output on line one. lcdLine2Cmd equ .128 + 0x40 ; The starting position on the LCD for decoded output on line two. Diag1 equ .128 + 0x40 ; The starting position on the LCD for diagnostic output. Diag2 equ .128 + 0x44 ; The starting position on the LCD for diagnostic output. Diag3 equ .128 + 0x48 ; The starting position on the LCD for diagnostic output. Diag4 equ .128 + 0x4C ; The starting position on the LCD for diagnostic output. Diag5 equ .128 + 0x50 ; The starting position on the LCD for diagnostic output. Ddra4Input equ B'00000000' ; Program port bits RA0 to RA3 as output pins & RA4 as output pin. led equ .4 ; RA4 runs LED that indicates presence of a tone. dled3 equ .3 ; RA3 runs debug LED3. dled2 equ .2 ; RA2 runs debug LED2. dled1 equ .1 ; RA1 runs debug LED1. dled0 equ .0 ; RA0 runs debug LED0. Ddrb4Input equ B'10001111' ; Program port bits RB0 to RB3 & RB7 as input pins & RB4 to RB6 as output pins. Ddrb4Output equ B'10000000' ReadCntrl equ B'10100000' ; Set LCD control lines E=0, R/W=1, RS=0. i.e. LCD Control register read. paddit equ 0x0d ; paddah equ 0x26 ; A largish value that when multiplied by tabsize still fits in a byte. code_dit_or_dah equ 0x01 ; The codeword representing first dit or dah received. noise_threshold equ 0x02 ; 16 milliseconds or less is noise. tabsize equ .4 ; The number of dit or dah measurements that will be stored in a table. ; Make it a power of two to ease the arithmetic. optest1 equ .128 + 0x14 ; The first LCD display DDRAM position on line one that is off screen. optest2 equ .128 + 0x54 ; The first LCD display DDRAM position on line two that is off screen. timer0_reload equ 0x09 ; Reload value is 0x09 = 9 Decimal i.e. 256 - 247 for ~6ms tick. symbol_limit equ .6 ; Variable symbol_count is considered good if in the range 0 <= symbol_count < symbol_limit. ; The "flags" bit assignments follow: dit_leads equ .7 ; Set (1) for leading DIT of a character, clear (0) for leading DAH of a character. overflow equ .6 ; Slow Morse code can cause the counter to overflow. lcdpresent equ .5 ; Set if the LCD is present and enabled. on_lcd_line2 equ .4 ; Clear if on line one of the LCD or set if on line two. DIT_start equ B'10000000' Timer_overflow equ B'01000000' LCD_on equ B'00100000' line_flag equ B'00010000' ; Indicate initialisation state of all flags flags_init equ 0 | LCD_on ; Switch on other bits like this: | DIT_start | Timer_overflow ; ******************************************************************************** ; Reserve memory (RAM) for various variables used in the program. org 0x20 temp_w res 1 ; Temporary store for W during the interrupt service routine. temp_w1 res 1 ; Temporary store for W during the debug print diagnostics. temp_status res 1 ; Temporary store for STATUS during the interrupt service routine. flags res 1 ; In here we will keep a record of certain flags. PortaImage res 1 ; A shadow copy of the state of port A. PortbImage res 1 ; A shadow copy of the state of port B. ACLowNibble res 1 ; Holds low nibble of Address Counter when LCD control register is read. timecnt res 1 ; This is incremented in the ISR, period res 1 ; and transferred here on edge detection. thres res 1 ; The computed symbol type decision threshold. cursorPos res 1 ; Cursor position on the LCD at which the next decoded character should be printed. nextDecodePos res 1 ; Saves the next decoded character cursor position during diagnostic output. lowNibble res 1 ; Temporary store for the low nibble info when displaying a byte in hex format. offScreen res 1 ; scratch1 res 1 ; scratch2 res 1 ; codeword res 1 ; A 1/0 representation of a Morse code character. symbol_count res 1 ; Counts how many symbols have been received so far for the current character. ; Do not split up these next 6 + tabsize + tabsize registers otherwise their initialisation will fail. ditptr res 1 ; Pointer to ditvals buffer. ditsum res 1 ditave res 1 ditvals res tabsize dahptr res 1 ; Pointer to dahvals buffer. dahsum res 1 dahave res 1 dahvals res tabsize ; ******************************************************************************** org 0x000 boot goto init ; Do the intialisation code first. ; ******************************************************************************** ; This interrupt service routine (ISR) is entered approximately every 6 milliseconds when an IRQ ; is received. org 0x004 ISR movwf temp_w ; Save the current value in the working register. movf STATUS,W ; Copy the status bits to W. movwf temp_status ; Save the current status bits. bcf STATUS,RP0 ; Select register bank 0. bcf PORTA,dled0 ; Low output turns the debug LED0 on. incf timecnt,F ; Increment the timer count. ; btfss STATUS,Z ; See if the timer count has just overflowed from 0xFF to 0x00. btfss timecnt,.6 ; See if the timer count has just overflowed from 0x3F to 0x40. goto isrjmp ; We do this jump if the Z bit is clear (incf result was non-zero). bsf flags,overflow ; Indicate that a timer overflow occurred. ; decf timecnt,F ; Decrement the timer count leaving it at 0xFF. I.e. saturate at 0xFF. decf timecnt,F ; Decrement the timer count leaving it at 0x3F. I.e. saturate at 0x3F. isrjmp movlw timer0_reload ; Get the timer 0 reload value. movwf TMR0 ; Place the reload value in TMR0. bcf INTCON,TMR0IF ; Clear down the interrupt generated by TMR0. exit1 movf temp_status,W ; Get the status bits we saved. bsf PORTA,dled0 ; High output turns the debug LED0 off. movwf STATUS ; Restore them to the status register. swapf temp_w,F ; temp_w(0:3) -> temp_w(4:7) -> File register. swapf temp_w,W ; temp_w(0:3) -> temp_w(4:7) -> W register i.e. W restored. retfie ; Return from the ISR. ; ******************************************************************************** ; Morse tables (see Rec. ITU-R M.1677) follow ISR to keep them in 1st page, hopefully. ; Each look up table consists of 64 (2^6) entries and codeword selects the entry to use. ; One table is for characters having a leading dit ; and the other table for characters with a leading dah. ; The codeword is constructed by rotation left. ; A one is always shifted into the codeword first to represent the leading dit or dah symbol. ; Subsequent symbols are shifted in at the least significant bit (LSB) position for each ; received dit/dah of a character. ; Leading dit => dit = 1 & dat = 0 in the codeword. ; Leading dah => dit = 0 & dah = 1 in the codeword. ; E.g. "a" => .- => 10, so codeword = 00000010 the third "retlw" list entry of the first table. ; E.g. "n" => -. => 10, so codeword = 00000010 the third "retlw" list entry of the second table. ditab clrf PCLATH ; Clear PCLATH. movf codeword,W ; Load W with the codeword. andlw B'00111111' ; We shall only use the six least significant bits. addwf PCL,1 ; PCL += W, point program counter (low byte) at the correct entry. retlw " " ; 00000000 => 0x20 - "DIT" Table 1st entry. retlw "e" ; 00000001 => 0x65 retlw "a" ; 00000010 => 0x61 retlw "i" ; 00000011 => 0x69 retlw "w" ; 00000100 => 0x77 retlw "r" ; 00000101 => 0x72 retlw "u" ; 00000110 => 0x75 retlw "s" ; 00000111 => 0x73 retlw "j" ; 00001000 => 0x6A retlw "p" ; 00001001 => 0x70 retlw 0x5f ; 00001010 => retlw "l" ; 00001011 => 0x6C retlw 0x5f ; 00001100 => retlw "f" ; 00001101 => 0x66 retlw "v" ; 00001110 => 0x76 retlw "h" ; 00001111 => 0x68 retlw "1" ; 00010000 => 0x31 retlw 0x5f ; 00010001 => retlw 0x5f ; 00010010 => retlw 0x5f ; 00010011 => retlw 0x5f ; 00010100 => retlw 0x2b ; 00010101 => "+" end of message retlw 0x5f ; 00010110 => retlw 0x5f ; 00010111 => "_" wait retlw "2" ; 00011000 => 0x32 retlw 0x5f ; 00011001 => retlw 0x5f ; 00011010 => retlw 0x5f ; 00011011 => retlw "3" ; 00011100 => 0x33 retlw "!" ; 00011101 => 0x21 acknowledge or understood retlw "4" ; 00011110 => 0x34 retlw "5" ; 00011111 => 0x35 retlw 0x5f ; 00100000 => retlw "'" ; 00100001 => 0x27 retlw 0x5f ; 00100010 => retlw 0x5f ; 00100011 => retlw 0x5f ; 00100100 => retlw "@" ; 00100101 => 0x40 commercial at (also known as "arobase") retlw 0x5f ; 00100110 => retlw 0x5f ; 00100111 => retlw 0x5f ; 00101000 => retlw 0x5f ; 00101001 => retlw "." ; 00101010 => 0x2E retlw 0x5f ; 00101011 => retlw 0x5f ; 00101100 => retlw 0x22 ; 00101101 => quotation mark retlw 0x5f ; 00101110 => retlw 0x5f ; 00101111 => retlw 0x5f ; 00110000 => retlw 0x5f ; 00110001 => retlw "_" ; 00110010 => 0x5F retlw "?" ; 00110011 => 0x3F (note of interrogation or request for repetition of a transmission not understood) retlw 0x5f ; 00110100 => retlw 0x5f ; 00110101 => retlw 0x5f ; 00110110 => retlw 0x5f ; 00110111 => retlw 0x5f ; 00111000 => retlw 0x5f ; 00111001 => retlw "<" ; 00111010 => 0x3C end of work retlw 0x5f ; 00111011 => retlw 0x5f ; 00111100 => retlw 0x5f ; 00111101 => retlw 0x5f ; 00111110 => retlw 0x5f ; 00111111 => assume an error dahtab clrf PCLATH ; Clear PCLATH. movf codeword,W ; Load W with the codeword. andlw B'00111111' ; We shall only use the six least significant bits. addwf PCL,1 ; PCL += W, point program counter at the correct entry. retlw " " ; 00000000 => 0x20 - "DAH" Table 1st entry. retlw "t" ; 00000001 => 0x74 retlw "n" ; 00000010 => 0x6E retlw "m" ; 00000011 => 0x6D retlw "d" ; 00000100 => 0x64 retlw "k" ; 00000101 => 0x6B invitation to transmit retlw "g" ; 00000110 => 0x67 retlw "o" ; 00000111 => 0x6F retlw "b" ; 00001000 => 0x62 retlw "x" ; 00001001 => 0x78 "x" or multiplication sign retlw "c" ; 00001010 => 0x63 retlw "y" ; 00001011 => 0x79 retlw "z" ; 00001100 => 0x7A retlw "q" ; 00001101 => 0x71 retlw 0x5f ; 00001110 => retlw 0x5f ; 00001111 => retlw "6" ; 00010000 => 0x36 retlw "=" ; 00010001 => 0x3D double dash retlw "/" ; 00010010 => 0x2F fraction bar retlw 0x5f ; 00010011 => retlw 0x5f ; 00010100 => retlw ">" ; 00010101 => 0x3E starting signal (to precede every transmission) retlw "(" ; 00010110 => 0x28 retlw 0x5f ; 00010111 => retlw "7" ; 00011000 => 0x37 retlw 0x5f ; 00011001 => retlw 0x5f ; 00011010 => retlw 0x5f ; 00011011 => retlw "8" ; 00011100 => 0x38 retlw 0x5f ; 00011101 => retlw "9" ; 00011110 => 0x39 retlw "0" ; 00011111 => 0x30 retlw 0x5f ; 00100000 => retlw "-" ; 00100001 => 0x2D retlw 0x5f ; 00100010 => retlw 0x5f ; 00100011 => retlw 0x5f ; 00100100 => retlw 0x5f ; 00100101 => retlw 0x5f ; 00100110 => retlw 0x5f ; 00100111 => retlw 0x5f ; 00101000 => retlw 0x5f ; 00101001 => retlw ";" ; 00101010 => 0x3B retlw "!" ; 00101011 => 0x21 retlw 0x5f ; 00101100 => retlw ")" ; 00101101 => 0x29 retlw 0x5f ; 00101110 => retlw 0x5f ; 00101111 => retlw 0x5f ; 00110000 => retlw 0x5f ; 00110001 => retlw 0x5f ; 00110010 => retlw "," ; 00110011 => 0x2C retlw 0x5f ; 00110100 => retlw 0x5f ; 00110101 => retlw 0x5f ; 00110110 => retlw 0x5f ; 00110111 => retlw ":" ; 00111000 => 0x3A retlw 0x5f ; 00111001 => retlw 0x5f ; 00111010 => retlw 0x5f ; 00111011 => retlw 0x5f ; 00111100 => retlw 0x5f ; 00111101 => retlw 0x5f ; 00111110 => retlw 0x5f ; 00111111 => ; ******************************************************************************** ; Initialisation code to get the LCD configured. lcd_init btfss flags,lcdpresent return call ChkBusy ; Prepare to write to the LCD using only the upper nibble of the LCD's data bus. movlw FuncSet41 ; Get the command we want to write to the LCD. call SendCmmd ; Strobe command to the LCD. movlw FuncSet42 ; Get the command we want to write to the LCD. call SendCmmd ; Strobe command to the LCD. movlw DisplayOn ; Get the command we want to write to the LCD. call SendCmmd ; Strobe command to the LCD. movlw EntryMode ; Get the command we want to write to the LCD. call SendCmmd ; Strobe command to the LCD. movlw InitDdRam ; Get the command we want to write to the LCD. call SendCmmd ; Strobe command to the LCD. movlw lcdLine1Cmd ; Load the command that will take us to the left most char on LCD line one. movwf cursorPos ; Initialise the starting position for writing stuff to the LCD. call SendCmmd ; Strobe command to the LCD. return ; ******************************************************************************** ; Initialisation code. ; Do clock dependant stuff. ; Next two opcodes used if xtal clock selected. ;init movlw 0x04 ; Divide XTAL OSC by 4 and then 32 for 4ms ticks. ; option ; Later, load TMR0 with 256-140 and let overflow. ; Next five opcodes used if RC clock selected. init bcf STATUS,RP1 ; We select register bank pair 0 or 1. movlw 0x02 ; Divide RC OSC by 4 and then 8 for ~6ms ticks. bsf STATUS,RP0 ; Select register bank 1. movwf OPTION_REG ; Later, load TMR0 with timer0_reload and let overflow. bcf STATUS,RP0 ; Select register bank 0. ; Setup ports A & B. movlw Ddra4Input ; Program RA0 to RA3 as output pins & RA4 as an output. bsf STATUS,RP0 ; Select register bank 1. movwf TRISA ; Program port A data direction register. bcf STATUS,RP0 ; Select register bank 0. bcf PORTA,led ; On initially - low output turns the LED on. bsf PORTA,dled3 ; High output turns the debug LED3 off. bsf PORTA,dled2 ; High output turns the debug LED2 off. bsf PORTA,dled1 ; High output turns the debug LED1 off. bsf PORTA,dled0 ; High output turns the debug LED0 off. movlw Ddrb4Input ; Program RB0 to RB3 & RB7 as input pins & RB4 to RB6 as output pins. bsf STATUS,RP0 ; Select register bank 1. movwf TRISB ; Program port B data direction register. bcf STATUS,RP0 ; Select register bank 0. ; Construct a delay loop by temporarily using the port A & B shadow registers. clrf PortbImage ; Start with port B shadow state all clear. clrf PortaImage ; Start with port A shadow state all clear. dlp1 decfsz PortaImage,F ; Count down using the port A shadow. goto dlp1 ; Keep counting down until we hit zero, then we skip this instruction. decfsz PortbImage,F ; Count down using the port B shadow. This forms an outer loop to the port A inner loop count. goto dlp1 ; Keep counting down until we hit zero, then we skip this instruction. ; Initialise the dit and dah pointers, sums, averages and tables. movlw .13 ; 1 + 1 + 1 + tabsize + 1 + 1 + 1 + tabsize. movwf ditptr ; Load the number of bytes to clear. movlw ditptr ; Load W with the address of ditptr. movwf FSR ; Set up indirect addressing so we can use INDF. ilp1 incf FSR,F ; Increment the FSR pointer to the next location. clrf INDF ; Clear the register pointed to by FSR decfsz ditptr,1 ; Decrease the count of registers to clear. goto ilp1 ; Loop back if there are more registers to clear. ; Pad the dit and dah buffers and set the initial averages so we get sensible behaviour quickly. movlw paddit movwf ditvals movwf ditvals + 1 movwf ditvals + 2 movwf ditvals + 3 movwf ditave movlw tabsize * paddit movwf ditsum movlw paddah movwf dahvals movwf dahvals + 1 movwf dahvals + 2 movwf dahvals + 3 movwf dahave movlw tabsize * paddah movwf dahsum movlw (paddit + paddah / 2) movwf thres ; Set the decision threshold. movlw timer0_reload ; Get timer 0 reload value. movwf TMR0 ; Place the reload value in the 8-bit real-time clock/counter TMR0. movlw flags_init ; Find out the initialisation state of all the flags. movwf flags ; Set initialisation state of all the flags. call lcd_init ; Initialise the LCD if it is present. Make sure this is done after flags setup. clrf INTCON ; Clear all interrupt enables and interrupt flags. bsf INTCON,TMR0IE ; Enable the TMR0 interrupts. bsf INTCON,GIE ; Enable all unmasked interrupts. ; Fall through to the first tone processing. ; ******************************************************************************** ; Process the very first tone received. await_space ; call test_interrupts ; Make sure interrupts are still running. btfss PORTB,code_in ; Sample the tone decoder signal on port B bit 7. ; The bit will be low (0) when a tone is present i.e. key-down. goto await_space ; Keep looping back to "await_space" while we are receiving a tone. ; The tone has now disappeared i.e. we've just hit the start of key-up period. bsf PORTA,led ; We are now receiving a space, so switch off the LED. await_tone ; call test_interrupts ; Make sure interrupts are still running. btfsc PORTB,code_in ; Sample the tone decoder signal on port B bit 7. goto await_tone ; Keep looping back to "await_tone" while there is no tone. ; Fall through to start_of_char. ; ******************************************************************************** ; Look for the first symbol of a codeword. ; By "symbol" we mean the dits or dahs that make up a character. ; We come back to here for detection and classification of ; the tone pulse that forms the first symbol of a character. start_of_char ; We have detected the start of a dit or dah, or noise from a station on a nearby frequency (or key bounce)! clrf symbol_count ; Start counting the incoming symbols. call measure_tone ; The tone has stopped, but we believe this is the first ; symbol of a character so we don't know what it is yet. ; We shall assume it is a dah on the very first pass through the code ; as flags was cleared and hence dit_leads = 0. movlw code_dit_or_dah ; The first symbol in a codeword is always represented by a one. movwf codeword ; Write the first symbol into the codeword. ; Look at the last tone/mark pulse measurement. movf thres,W ; Load the dit/dah threshold into the W register. subwf period,W ; Calculate W = (period - thres). btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if period >= thres. goto isadah ; We think we heard a dah as the tone period >= thres. ; We think we heard a dit as the tone period < thres. isadit bsf flags,dit_leads ; Set (1) as we believe the next character has a leading dit. call avedit ; Update the dit average given the new dit. goto codeword_loop ; We think we heard a dah as the tone period >= thres. isadah bcf flags,dit_leads ; Clear (0) as we believe the next character has a leading dah. call avedah ; Update the dah average given the new dah. ; Fall through into the main program loop. ; ******************************************************************************** ; Compile the rest of the codeword symbol by symbol. ; We come back to here for each tone pulse detected other than the first symbol of a character. ; Now we wait for a tone to start again so we can see what kind of space just passed. codeword_loop ; call test_interrupts ; Make sure interrupts are still running. movf thres,W ; Load the dit/dah threshold into the W register. ; The same threshold can be used to distinguish ; between inter symbol and inter character spaces. subwf timecnt,W ; Calculate W = (timecnt - thres). btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if timecnt >= thres. goto trim_space ; We have only heard what might be an inter symbol space so far so continue listening for a tone. btfsc PORTB,code_in ; Sample the tone decoder signal on port B bit 7. goto codeword_loop ; Keep looping back to "codeword_loop" while there is no tone. ; A tone has started again. incf symbol_count ; Count this symbol. call measure_tone ; Look at the last tone/mark pulse measurement. movf thres,W ; Load the dit/dah threshold into the W register. subwf period,W ; Calculate W = (period - thres). btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if period >= thres. goto itsadah ; We think we heard a dah as the tone period >= thres. ; goto itsadit ; We think we heard a dit as the tone period < thres. ; ******************************************************************************** ; We think we heard a dit as the tone period < thres. itsadit call avedit ; Update the dit average given the new dit. btfsc flags,dit_leads bsf STATUS,C ; Leading symbol = dit => Use Carry = 1 for dits. btfss flags,dit_leads bcf STATUS,C ; Leading symbol = dah => Use Carry = 0 for dits. rlf codeword,F ; Rotate left the next symbol into the codeword. goto codeword_loop ; Find next tone start. ; ******************************************************************************** ; We think we heard a dah as the tone period >= thres. itsadah call avedah ; Update the dah average given the new dah. btfss flags,dit_leads bsf STATUS,C ; Leading symbol = dah => Use Carry = 1 for dahs. btfsc flags,dit_leads bcf STATUS,C ; Leading symbol = dit => Use Carry = 0 for dahs. rlf codeword,F ; Rotate left the next symbol into the codeword. goto codeword_loop ; Find next tone start. ; ******************************************************************************** ; We want to time the period for which a tone is present. measure_tone clrf timecnt ; Reset the timer count to start measuring the tone/mark period. It will increment each time the ISR runs. bcf flags,overflow ; Clear timer overflow flag. bcf PORTA,led ; Light the LED to indicate we are hearing a tone. debounce ; call test_interrupts ; Make sure interrupts are still running. movlw noise_threshold ; Debounce the tone edge. Load W with the noise threshold. subwf timecnt,W ; Calculate W = (timecnt - noise_threshold). btfss STATUS,C ; The Carry bit (NOT-Borrow) is set if timecnt >= noise_threshold. goto debounce ; Keep looping back to "debounce" until we've waited longer than the noise threshold. ; We have exceeded the debounce period. Now wait for the end of the tone. wait_for_space ; call test_interrupts ; Make sure interrupts are still running. btfss PORTB,code_in ; Sample the tone decoder signal on port B bit 7. goto wait_for_space ; Keep looping back to wait_for_space while we are receiving a tone. ; The tone has stopped. movf timecnt,W ; Take a snapshot of the timer count. Once in W the ISR can no longer affect our measurement. movwf period ; Record the timer count measurement of the tone/mark period. ;TO DO: Record overflow flag also. clrf timecnt ; Reset the timer count to start measuring the space period. bcf flags,overflow ; Clear timer overflow flag. bsf PORTA,led ; We are now receiving a space, so switch off the LED. return ; ******************************************************************************** ; Processing for spaces longer than an inter symbol space. trim_space clrf timecnt ; Reset the timer count to trim the space period by the threshold interval. bcf flags,overflow ; Clear timer overflow flag. ; The space so far is long enough to be either an inter character or an inter word space so now decode and print out the char. ; Check number of symbols received. movlw symbol_limit subwf symbol_count,W ; Calculate W = (symbol_count - symbol_limit). btfss STATUS,C ; The Carry bit (NOT-Borrow) is set if symbol_count >= symbol_limit. goto good_symb_count ; Too many symbols to allow us to use the dit and dah tables so assume an error (eight dits). movlw 0x5f ; Load an ASCII "_" character into W. call SendText ; Print the character in W by sending it to the LCD. goto codeword_loop2 good_symb_count btfsc flags,dit_leads ; Workout what table to use given the dit_leads flag value. goto ditstart call dahtab ; Look up the character and return its ASCII value in W. goto char_of_word ditstart call ditab ; Look up the character and return its ASCII value in W. char_of_word call SendText ; Print the character in W by sending it to the LCD. codeword_loop2 ; call test_interrupts ; Make sure interrupts are still running. movf thres,W ; Load the dit/dah threshold into the W register. ; The same threshold can be used to distinguish ; between inter character and inter word spaces. subwf timecnt,W ; Calculate W = (timecnt - thres). btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if timecnt >= thres. goto trim_again ; We have only heard what might be an inter character space so far so continue listening for a tone. btfsc PORTB,code_in ; Sample the tone decoder signal on port B bit 7. goto codeword_loop2 ; Keep looping back to "codeword_loop2" while there is no tone. ; A tone has started again. goto start_of_char trim_again clrf timecnt ; Reset the timer count to trim the space period by the threshold interval. bcf flags,overflow ; Clear timer overflow flag. codeword_loop3 ; call test_interrupts ; Make sure interrupts are still running. movf thres,W ; Load the dit/dah threshold into the W register. ; The same threshold can be used to distinguish ; between inter character and inter word spaces. subwf timecnt,W ; Calculate W = (timecnt - thres). btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if timecnt >= thres. ; A period roughly equivalent to six dit periods has elapsed without a tone starting so we can print out an interword space. goto print_interword_space ; We have only heard what might be an inter character space so far so continue listening for a tone. btfsc PORTB,code_in ; Sample the tone decoder signal on port B bit 7. goto codeword_loop3 ; Keep looping back to "codeword_loop3" while there is no tone. ; A tone has started again. goto start_of_char print_interword_space ; The space so far is long enough to be an inter word space so now print out a space char. movlw 0x20 ; Load an ASCII space character into W. call SendText ; Print the character in W by sending it to the LCD. goto await_tone ; ******************************************************************************** ; Update the dit average given the new dit period measurement. avedit movf ditptr,W ; Load W with the index into the ditvals (dit values) buffer for the oldest measurement. addlw ditvals ; Add the address of the start of the ditvals buffer. movwf FSR ; Set up indirect addressing so we can use INDF. movf INDF,W ; Load W with the value at the indexed position in the ditvals buffer. subwf ditsum,F ; Calculate (new)ditsum = ((old)ditsum - W). Remove the oldest measurement from the sum. movf period,W ; Load the measured period of the latest dit into W. movwf INDF ; Save it to the ditvals buffer overwriting the oldest measurement. addwf ditsum,F ; Calculate (new)ditsum = ((old)ditsum + W). Add the latest measurement to the sum. rrf ditsum,W ; Divide ditsum by two and save result in W. ; N.B. Carry may not be clear because of the addwf instuction. movwf ditave ; Save the result so far in ditave. ; It's not the right quantity yet, it's double the average! rrf ditave,F ; Divide ditave by two to generate the correct average value. movlw 0x3f ; Load a mask that we shall use to clear the two most significant bits. andwf ditave,F ; Apply the mask to ditave. ; This counteracts the two possibly non-zero Carry bits rotated in by the rrf instructions. incf ditptr,F ; Increment the index into the ditvals buffer. movlw tabsize - 1 ; But we may have gone past the last entry in the buffer, so load a mask value. andwf ditptr,F ; Use the mask value to enforce a wrap back to the beginning of the buffer. goto estimate_threshold ; Now go update our estimate of the dit/dah threshold. ; ******************************************************************************** ; Update the dah average given the new dah period measurement. avedah movf dahptr,W ; Load W with the index into the dahvals (dah values) buffer for the oldest measurement. addlw dahvals ; Add the address of the start of the dahvals buffer. movwf FSR ; Set up indirect addressing so we can use INDF. movf INDF,W ; Load W with the value at the indexed position in the dahvals buffer. subwf dahsum,F ; Calculate (new)dahsum = ((old)dahsum - W). Remove the oldest measurement from the sum. movf period,W ; Load the measured period of the latest dah into W. movwf INDF ; Save it to the dahvals buffer overwriting the oldest measurement. addwf dahsum,F ; Calculate (new)dahsum = ((old)dahsum + W). Add the latest measurement to the sum. rrf dahsum,W ; Divide dahsum by two and save result in W. ; N.B. Carry may not be clear because of the addwf instuction. movwf dahave ; Save the result so far in dahave. ; It's not the right quantity yet, it's double the average! rrf dahave,F ; Divide dahave by two to generate the correct average value. movlw 0x3f ; Load a mask that we shall use to clear the two most significant bits. andwf dahave,F ; Apply the mask to dahave. ; This counteracts the two possibly non-zero Carry bits rotated in by the rrf instructions. incf dahptr,F ; Increment the index into the dahvals buffer. movlw tabsize - 1 ; But we may have gone past the last entry in the buffer, so load a mask value. andwf dahptr,F ; Use the mask value to enforce a wrap back to the beginning of the buffer. ; Fall through to estimate_threshold. ; ******************************************************************************** ; Update our estimate of the dit/dah threshold. ; We shall estimate the threshold to be the period ; exactly halfway between the dit and dah averages. estimate_threshold bcf PORTA,dled2 ; Low output turns the debug LED2 on. bsf PORTA,dled2 ; High output turns the debug LED2 off. movf ditave,W ; Use our averaged dit and dah values. subwf dahave,W ; Calculate W = (dahave - ditave). movwf thres ; Save result to threshold register. bcf STATUS,C ; Clear the Carry bit. rrf thres,F ; Divide by 2. movf ditave,W ; Load W with the smaller of the two averages. addwf thres,F ; Add the divided by 2 value to obtain the new threshold. ; Fall through to lcd_position_test. ; ******************************************************************************** ; Monitor LCD writing position to make sure we stay on screen. ; Reconstruct the current LCD writing position from the data in PortbImage and ACLowNibble. lcd_position_test ; swapf ACLowNibble,W ; Swap the L.S.Nibble of the read AC data to its correct position in the L.S.Nibble of W. ; andlw 0x0f ; Mask out the rubbish in the upper nibble. ; movwf ACLowNibble ; Put it back in storage. ; movf PortbImage,W ; Load W with the most significant nibble of the read AC data. ; andlw 0x70 ; Mask out the rubbish in the lower nibble and what was the BF (busy flag). ; iorwf ACLowNibble,W ; Inclusive OR the two nibbles together, leaving the result in W. ; movwf cursorPos ;DEBUG Save the next position for writing decoded characters. ; incf cursorPos,F ; Save the next position for writing decoded characters. #ifndef diagnostics movlw optest1 ; Load the test value that determines if the next decoded character would be written off the end of line 1. btfsc flags,on_lcd_line2 movlw optest2 ; Load the test value that determines if the next decoded character would be written off the end of line 2. subwf cursorPos,W ; Calculate W = (cursorPos - optestX). btfss STATUS,C ; The Carry bit (NOT-Borrow) is set if cursorPos >= optestX. return off_screen movlw lcdLine1Cmd ; Load the command that will take us to the left most char on LCD line one. btfss flags,on_lcd_line2 movlw lcdLine2Cmd ; Load the command that will take us to the left most char on LCD line two. movwf cursorPos ; Copy the nextDecodePos cursor position into cursorPos. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movlw line_flag ; Pick out thr flag "on_lcd_line2". xorwf flags,F ; Toggle it. return #else movlw optest1 ; Load the test value that determines if the next decoded character would be written off screen. subwf cursorPos,W ; Calculate W = (cursorPos - optest1). movf cursorPos,W ; Reload the cursor position into W. btfsc STATUS,C ; The Carry bit (NOT-Borrow) is set if cursorPos >= optest1. beyond_row_one movlw lcdLine1Cmd ; Load the command that will take us to the left most char on LCD line one. movwf nextDecodePos ; Save the next position command for writing decoded characters. ; ******************************************************************************** ; Use our LCD display routines to present diagnostic info to the user. print_diagnostics movlw Diag1 ; Load W with the required LCD cursor position. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movf period,W ; Load W with the measured period. call print_byte_as_hex; Convert the integer value in W to ASCII and print it to LCD. movlw Diag2 ; Load W with the required LCD cursor position. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movf ditave,W ; Load W with the smaller of the two averages. call print_byte_as_hex; Convert the integer value in W to ASCII and print it to LCD. movlw Diag3 ; Load W with the required LCD cursor position. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movf dahave,W ; Load W with the larger of the two averages. call print_byte_as_hex; Convert the integer value in W to ASCII and print it to LCD. movlw Diag4 ; Load W with the required LCD cursor position. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movf thres,W ; Load W with the threshold value. call print_byte_as_hex; Convert the integer value in W to ASCII and print it to LCD. movlw Diag5 ; Load W with the required LCD cursor position. call SendCmmd ; Command the LCD module to start writing from a new cursor position. movf nextDecodePos,W ; Load W with the cursor position to be written to next. call print_byte_as_hex; Convert the integer value in W to ASCII and print it to LCD. movf nextDecodePos,W ; Restore the LCD to the cursor position for writing the next decoded character to. movwf cursorPos ; Copy the nextDecodePos cursor position into cursorPos. call SendCmmd ; Command the LCD module to start writing from a new cursor position. return ; Return from the call to avedit or avedah. #endif ;diagnostics ; ******************************************************************************** ; General purpose delay loop. delay_loop clrf scratch2 ; Start with scratch2 all clear. clrf scratch1 ; Start with scratch1 all clear. dlp3 decfsz scratch1,F ; Count down using scratch1. goto dlp3 ; Keep counting down until we hit zero, then we skip this instruction. decfsz scratch2,F ; Count down using scratch2. This forms an outer loop to the scratch1 inner loop count. goto dlp3 ; Keep counting down until we hit zero, then we skip this instruction. return ; ******************************************************************************** ; LCD Controller Information. ; DISPLAY COMMAND TABLE for Epson SED1278F/D Dot Matrix LCD Controller Driver. ; Parameter RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Note ; CLEAR DISPLAY 0 0 0 0 0 0 0 0 0 1 ; CURSOR HOME 0 0 0 0 0 0 0 0 1 1 ; ENTRY MODE SET 0 0 0 0 0 0 0 1 I/D I/D DB1=1: Increment, DB1=0: Decrement ; DB0=1: The display is shifted. ; DB0=0: The display is not shifted. ; DISPLAY ON/OFF 0 0 0 0 0 0 1 D C C DB2=1: Display on, DB2=0: Display off ; DB1=1: Cursor on, DB1=0: Cursor off ; DB0=1: Blinking on, DB0=0: Blinking off ; CURSOR/DISPLAY SHIFT 0 0 0 0 0 1 S/C R/L * * DB3=1: Shifts display one character ; DB2=1: Right shift, DB2=0: Left shift ; SYSTEM SET 0 0 0 0 1 DL N F * * DB4=1: 8 bits, DB4=0: 4 bits ; DB3=1: 2 line display (1/16 duty), ; DB3=0: 1 line display ; DB2=1: 5x10 dots, 1/11 duty ; DB2=0: 5x7 dots, 1/8 duty ; SET CGRAM ADDRESS 0 0 0 1 Acg (DB0 to 5) The address length that can be set is 64 addresses. ; SET DDRAM ADDRESS 0 0 1 Add (DB0 to 6) The address length that can be set is 80 addresses. ; READ BUSY FLAG/ 0 1 BF AC (DB0 to 6) DB7=1: Busy (instruction not accepted) ; ADDRESS COUNTER DB7=0: Ready (instruction accepted) ; WRITE DATA 1 0 Write Data ; READ DATA 1 1 Read Data ; * => Don't Care. ; ******************************************************************************** ; Subroutines SendText & SendCmmd. A byte of command or data is passed to these ; subroutines in the working register, W, and is written to the command or data ; register of the LCD using two nibble transfers employing only the most significant ; nibble of the LCD's data bus. SendText btfss flags,lcdpresent return clrf PORTB ; Prepare for an LCD Control register write. bsf PORTB,RS ; Switch to the LCD's data register. incf cursorPos,F ; Keep track of where the cursor is. goto Send1 ; Strobe the command passed in the working register through to the LCD. SendCmmd btfss flags,lcdpresent return clrf PORTB ; Prepare for an LCD Control register write. Send1 movwf PortbImage ; Copy the command or data to the port B shadow register. swapf PortbImage,W ; Swap the two port B shadow nibbles and put result in W. andlw 0x0f ; Select the lower nibble of W i.e. the upper nibble of the command/data. iorwf PORTB,1 ; Inclusive OR W and port B (for the LCD control bus bits) then send the result back to port B. bsf PORTB,E ; Strobe E set. N.B. This strobe is active high. bcf PORTB,E ; Strobe E cleared completing the write of the most significant nibble of the command/data. movlw 0xf0 ; Load mask into W for the upper nibble. andwf PORTB,1 ; AND W and port B thus clearing the most significant nibble of the LCD's data bus and then send result back to port B. movf PortbImage,W ; Recover from the port B shadow into W the original command/data we were asked to write. andlw 0x0f ; Get the least significant nibble of the command/data. iorwf PORTB,1 ; Inclusive OR W and port B (for the LCD control bus bits) then send the result back to port B. bsf PORTB,E ; Strobe E set. N.B. This strobe is active high. bcf PORTB,E ; Strobe E cleared completing the write of the least significant nibble of the command/data. ; N.B. Subroutines SendText & SendCmmd fall through into the ChkBusy routine and return from there. ; ******************************************************************************** ; Subroutine ChkBusy. Queries the LCD controller until it is in the not busy state. ; Then reconfigures port B in preparation for writing to the LCD. ChkBusy btfss flags,lcdpresent return movlw Ddrb4Input ; Program RB0 to RB3 & RB7 as input pins & RB4 to RB6 as output pins. bsf STATUS,RP0 ; Select register bank 1. movwf TRISB ; Program port B data direction register. bcf STATUS,RP0 ; Select register bank 0. SampleAgain bcf PORTA,dled3 ; Low output turns the debug LED3 on. bsf PORTA,dled3 ; High output turns the debug LED3 off. movlw ReadCntrl ; Get LCD control line values. movwf PORTB ; Start an LCD Control register read. bsf PORTB,E ; Bring the LCD strobe control line, E, back high to read the most significant nibble. movf PORTB,W ; Read the data presented on port B. movwf PortbImage ; Copy it to the port B shadow state. bcf PORTB,E ; Bring the LCD strobe control line, E, low. bsf PORTB,E ; Bring the LCD strobe control line, E, high to read the least significant nibble. movf PORTB,W ; Read the data presented on port B. movwf ACLowNibble ; Copy it to the storage location for the Address Counter least significant nibble. bcf PORTB,E ; Bring the LCD strobe control line, E, low. btfsc PortbImage,busy ; Test the "busy" bit i.e. LCD data bus bit 7. goto SampleAgain ; Go back for another test if the LCD controller is still busy. movlw Ddrb4Output ; LCD controller not busy ("busy" bit = 0), so prepare for port B output. bsf STATUS,RP0 ; Select register bank 1. movwf TRISB ; Program port B data direction register for RB0 to RB6 as output pins. RB7 remains an input pin. bcf STATUS,RP0 ; Select register bank 0. return ; Return knowing LCD is not busy and port B is configured to be written to. ; ******************************************************************************** ; Subroutine move_cursor. Moves the LCD cursor to the position indicated in the W register. move_cursor ; TO DO return ; ******************************************************************************** ; Subroutine print_itoa. Turns an unsigned 8-bit integer value passed in the W ; register into an ASCII string that is printed to the current cursor position ; on the LCD. We shall see a number in the range 0 to 255 plus a trailing space. ; Exactly four characters will be written. print_itoa ; TO DO return ; ******************************************************************************** ; print_byte_as_hex displays a byte passed in W as two hexadecimal characters on the LCD. ; Exactly three characters will be written, the third character being a trailing space. ; The ASCII string is printed at the current cursor position on the LCD. print_byte_as_hex btfss flags,lcdpresent return movwf lowNibble ; Save the lower nibble for later. swapf lowNibble,W ; Swap the upper nibble to the lower nibble position. call nibble_to_ASCII ; Convert the lower nibble to ASCII. call SendText ; Send this character to the LCD. movf lowNibble,W ; Recover the lower nibble. call nibble_to_ASCII ; Translate it also. call SendText ; Send this character to the LCD. movlw 0x20 ; Prepare to send a trailing ASCII space character. call SendText ; Send this character to the LCD. return ; ******************************************************************************** ; Routine to translate the lower nibble of the W register to an ASCII character in the W register. nibble_to_ASCII bcf STATUS,C ; Clear the Carry bit. andlw B'00001111' ; Mask out the upper nibble. addlw -.10 ; Set carry if W value was in the range 0 to 9. btfsc STATUS,C ; Skip next instruction for numeric characters (carry clear for numerics and set for alpha). goto alpha_value ; W value was in the range 10 to 15. addlw .10 + A'0' ; Add ten to restore range to 0 to 9, then A'0' to produce equivalent ASCII characters. return alpha_value addlw A'A' ; Add A'A' to produce equivalent ASCII characters. I.e. (0..5) + A'A' => (A'A'..A'F'). return ; ******************************************************************************** ; Routine to test that the interrupts are still running. test_interrupts movwf temp_w1 ; Save the current value in the working register. bcf PORTA,dled1 ; Low output turns the debug LED1 on. btfss INTCON,TMR0IE ; Skip next instruction if bit is set. goto locked_up ; Timer interrupt got switched off. btfss INTCON,GIE ; Skip next instruction if bit is set. locked_up goto locked_up ; Global interrupt enable got switched off. bsf PORTA,dled1 ; High output turns the debug LED1 off. movf temp_w1,W ; Restore the working register. return ;********************************************************************** ; This version is based on use of an NE567 tone decoder as input filter. ; Decoder output is low when a tone is detected, but only if VCO set close to the Morse tone frequency. ; Advantages: Immunity to adjacent channel signal, and amplitude variation. ; ; Timing considerations, how long is a symbol? ; The reference symbol duration is the DIT! ; A DAH symbol is 3 DITs long. ; The space between a pair of symbols is 1 DIT long. ; Characters are groups of symbols and the spaces between them. ; The space between characters is 3 DITs long. ; The space between words is 7 DITs long (according to Rec. ITU-R M.1677). ; There are 50 symbol periods in the reference string: PARIS ; ". _ _ . . _ . _ . . . . . . " ; so at 12 WPM, we have 600 symbols in 60 seconds, => 0.1 sec / symbol ; @ 36 WPM, the shortest (DIT) symbol period is 33ms long. ;********************************************************************** end