;********************************************************************** ; f627-10mhz.asm * ; This file is code for a gps locked frequency standard * ; on the PICmicro PIC16F627. * ;********************************************************************** ; * ; Filename: f627-10mhz.asm * ; Date: Mar 24 2003 * ; File Version: * ; * ; Author: Lawrence Glaister VE7IT * ; Company: Glaister Consulting * ; * ; * ;********************************************************************** ; * ; Files required: * ; p16f627.inc * ; * ; * ;********************************************************************** ; * ; Notes: * ; * ; - build using * ; assembler package found at * ; http://gputils.sourceforge.net/ or download page of * ; https://sourceforge.net/project/showfiles.php?group_id=41924 * * ; gpasm f627-10mhz.asm * ; * ;OLD: tpasm -l f627-10mhz.lst -o intel f627-10mhz.hex f627-10mhz.asm * ; - burn using * ; pp627 ( a modified version of pp84 by L.P Glaister ) * ; pp627 f627-10mhz.hex * ; * ;********************************************************************** list p=16f627, n=58, c=80 ; list directive to define processor radix dec #include ; processor specific variable definitions ; turn off crossing page boundary message ; ERRORLEVEL -306, -302 ; see page 96 of data sheet for description of config bits ; code protection off ; watch dog timer off ; brown out detection on ; power up timer enabled ; high speed xtal osc ; master clear pin used ; low voltage programming off ; NOTE: rb4 pin 10 must be pulled low (510ohms to gnd) to be ; sure HVP mode will work. __CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _HS_OSC & _MCLRE_ON & _LVP_OFF ; THESE 4 NIBBLES CAN BE USED FOR SOFTWARE VERSION NUMBER __idlocs H'F0AD' XTAL_FREQ equ 11064595 ; marked 11.0592 mhz (from 8051 project) FAM_17 equ 0 ; not a 17xxx family pic (for baud macro) ; I/O defns for MAX541 16 bit DAC on port A DAC_CS equ 2 ; MAX541 /cs DAC_CLK equ 1 ; MAX541 clk DAC_DAT equ 0 ; MAX541 data ;***** RAM LOCATION DEFINITIONS ; locations 70-7f are common to all 4 banks (no bank select issues) ; Bank 0 has 96 bytes of general purpose regs 20h-7fh (hi 16 are common to all banks) ; *** Bank0 *** 80 bytes 0x20 - 0x6f CBLOCK 0x020 ACCaLO ;16 bit math accumulator ACCaHI ACCbLO ;16 bit math accumulator ACCbHI dac_h dac_l ; output word for max541 16 bit dac temp1 ; temp for led flash routine dac_tmp ; temp for bit counter in update dac routine dac_sr ; temp sr for clocking MAX541 ser_cnt ; serial byte counter ser_last ; last ser char rx'd ser_b60 ; gps exponent/sign word ser_b61 ; gps exponent/sign word exp_h ; exponent of freq error reported by gps exp_l gps_err ; flag indicating dac limits exceeded flasher ; counter used for flashing led display ENDC ; *** Bank1 *** 80 bytes 0xA0 - 0xEF CBLOCK 0x0A0 ENDC ; *** Bank2 *** 48 Bytes 0x120 - 0x14f CBLOCK 0x120 ENDC ; *** Bank0/1/2/3 mirrored in all banks 0x70, 0xF0, 0x170, 0x1F0, 16 bytes CBLOCK 0x070 w_temp ; variable used for context saving status_temp ; variable used for context saving ENDC ; ORG H'2100' ; DE "(c)2003 L.P. Glaister" BLED1 EQU 0 ; o/p led BLED2 EQU 3 ; o/p led SOH EQU 1 ; start of header char in serial stream ;********************************************************************** ; MACROS ;******************** ; ; Macro UART_BAUD ; ; This macro sets assembler variables to indicate the best baud rate ; generator configuration for the USART in asynchronous mode, given the ; desired baud rate and the oscillator frequency. No code is generated. ; The following assembler variables are set: ; ; VAL_SPBRG - Value for the SPBRG baud rate generator register. ; ; BAUD_REAL - Real (not desired) baud rate resulting from the ; selected settings. ; ; VAL_TXSTA - Value for the TXSTA regisIB4 In addition to ; selecting the proper baud rate generator configuration, this ; value also selects the following: ; ; Asynchronous mode ; 8 bits per character ; transmitter enabled ; ; This macro produces an assembly time warning if the closest available ; baud rate is more then 2.9% from the desired baud rate (off by 25% of ; a bit time in the middle of the last bit). It produces an assembly ; error if the baud rate error is 5.8% or higher. ; uart_baud macro baud local err ;baud rate error in parts per 1000 ; ; Init values assuming will use high speed mode. ; if FAM_17 ;17Cxx family doesn't have high speed mode val_txsta set (1 << TXEN) ;set TXSTA register value else val_txsta set (1 << TXEN) | (1 << BRGH) ;init TX config for high speed mode endif val_spbrg set XTAL_FREQ * 16 / baud - 256 ;find divider value, 8 fraction bits val_spbrg set (val_spbrg + 128) >> 8 ;round and scale to final SPBRG value baud_real set XTAL_FREQ / (16 * (val_spbrg + 1)) ;find actual selected baud rate ; ; Switch to low speed mode if the baud rate generator value would require ; more than 8 bits to represent, or this chip has not high speed mode. ; if (val_spbrg > 255) || FAM_17 ;too slow for high speed mode or no HS ? if ! FAM_17 val_txsta set val_txsta & ~(1 << BRGH) ;disable high speed mode endif val_spbrg set XTAL_FREQ * 4 / baud - 256 ;find divider value, 8 fraction bits val_spbrg set (val_spbrg + 128) >> 8 ;round and scale to final SPBRG value if val_spbrg > 255 ;clip at largest allowable baud rate generator value val_spbrg set 255 endif baud_real set XTAL_FREQ / (64 * (val_spbrg + 1)) ;find actual selected baud rate endif err set (1000 * (baud_real - baud)) / baud ;baud rate err in parts/1000 if err < 0 err set -err ;make absolute value of error endif if err > 58 error "Baud rate error exceeds 5.8%" endif if err > 29 messg "WARNING: Baud rate error exceeds 2.9%" endif endm ; Alternate calcs to check baud rate divisor ; Calculates baudrate when BRGH = 0, adjust for rounding errors brgh0 equ ((((10*XTAL_FREQ/(64*9600))+5)/10)-1) ; Calculates baudrate when BRGH = 1, adjust for rounding errors brgh1 equ ((((10*XTAL_FREQ/(16*9600))+5)/10)-1) ;********************************************************************** ORG 0x000 ; processor reset vector NOP ; required for the ICD CLRF STATUS ; ensure we are at bank0 CLRF PCLATH ; ensure page bits are cleared ( before GOTO xxx !!! ) goto start ; go to beginning of program ORG 0x004 ; interrupt vector location movwf w_temp ; save off current W register contents movf STATUS,W ; move status register into W register movwf status_temp ; save off contents of STATUS register ; isr code can go here or be located as a call subroutine elsewhere movf status_temp,W ; retrieve copy of STATUS register movwf STATUS ; restore pre-isr STATUS register contents swapf w_temp,F swapf w_temp,W ; restore pre-isr W register contents retfie ; return from interrupt start MOVLW B'11111111' ; PORT REGS TO DEFAULTS MOVWF PORTA MOVLW B'11111111' MOVWF PORTB MOVLW 7 ; turn comparators off MOVWF CMCON ; and enable pins for I/O BSF STATUS,RP0 ; OPTION & TRIS ARE HI REGS MOVLW B'00000111' ; B7: RBPU - ENABLE PORT B PULL-UP RES, 0=OFF ; B6: INTEDG - RB0 INT EDGE SEL 0=-VE ; B5: T0CS - TMR0 SOURCE, 0=FOSC/4, 1=RA4 PIN ; B4: T0SE - RA4CLK PIN EDGE SELECT, 0=+VE ; B3: PSA - PRESCALE ASSIGN 0=TIMER, 1=WDG ; B2-0: PS2-0 - PRESCALE RATE 111=256 FOR TIMER (=127 FOR WDT) MOVWF OPTION_REG MOVLW B'11000110' ; 0=OUTPUT MOVWF TRISB MOVLW B'11100000' ; 1=INPUT MOVWF TRISA BCF STATUS,RP0 ; BACK TO LO REGS MOVLW B'00000000' ; B7: GIE - GLOBAL INT ENABLE, 0=OFF ; B6: EEIE - EERAW WRITE DONE INT ENABLE, 0=OFF ; B5: T0IE - TMR0 O/FLOW INT ENABLE, 0=OFF ; B4: INTE - RB0 INT ENABLE, 0=OFF ; B3: RBIE - PORTB CHANGE-OF-STATE INT ENABLE, 0=OFF ; B2: T0IF - TMR0 O'FLOW FLAG, 1=O/FLOW, S/WARE MUST RESET ; B1: INTF - RB0 INT FLAG, ACTIVE HIGH ; B0: RBIF - PORTB CHANGE-OF-STATE FLAG, ACTIVE HIGH MOVWF INTCON call init_uart ; call init_gps ; init the gps board movlw H'80' movwf dac_h clrf dac_l call dacout ; set dac to 32768 start01 bcf PORTA,4 ; +sign led on ; set all error leds on bcf PORTB,0 ; led on bcf PORTB,3 ; led on bcf PORTB,4 ; led on bcf PORTB,5 ; led on main bsf PORTA,3 ; yellow led off IDLE clrf ser_cnt ; zero packet byte counter btfss PIR1,RCIF ; check for received data goto main ; this may be start of pkt if we are lucky bcf PORTA,3 ; yellow led on for duration of pkt processing movf RCREG,W ; save received data in W sublw SOH btfss STATUS,Z goto main ; keep looking for SOH ; got SOH, look for packet ID byte call receive sublw H'15' ; look for packet id = 21 btfss STATUS,Z goto main ; keep looking for SOH ; got packet 21 id byte, now look for complement of it call receive sublw H'ea' ; look for packet id = /21 btfss STATUS,Z goto main ; keep looking for SOH ; ok, next byte is the packet length 0..255 call receive clrf ser_cnt ; setup counter for offsets into body ; now comes the body ; we are interested in only 2 bytes ; buff[61] & 0x80 is the sign bit of osc error ; exp = ((buff[61] & 0x7f) << 4) + ((buff[60] & 0xf0) >> 4) - 1023; main01 call receive movwf ser_last incf ser_cnt,f ; start walking up the counter movf ser_cnt,w sublw D'61' ; discard 1st 60 bytes btfss STATUS,Z goto main01 ; byte counter == 61 movfw ser_last movwf ser_b60 call receive movwf ser_b61 ; sign of error = buff[61] & 0x80 ; first red led indicate sign of error bsf PORTA,4 ;turn off +led btfss ser_b61,7 bcf PORTA,4 ;+led on ; exp = ((buff[61] & 0x7f) << 4) + ((buff[60] & 0xf0) >> 4) - 1023 ; typical values are -30 to -37 with -37 about 1e-12 and -32 about 1e-8 movf ser_b60,w movwf exp_l movf ser_b61,w movwf exp_h rrf exp_h,f rrf exp_l,f ;shift everybody down 4 places rrf exp_h,f rrf exp_l,f rrf exp_h,f rrf exp_l,f rrf exp_h,f rrf exp_l,f movlw H'07' ; clean up unused upper bits andwf exp_h,f ; if the exponent == 0, we have serial com with gps, but gps has ; not aquired satelites yet. btfsc STATUS,Z goto start01 ; big error condx ; at this point exp will be 993 (big error) to 986 (small error) call clrled ; turn off all 4 error magnitude leds ; we use the binary exponent to determine the rate of ; correction of the dac voltage. Big errors get fast ; correction, and small errors get no correction. call loadacc ; accA = exponent ; accB = smallest error constant movlw D'989' & H'ff' movwf ACCbLO movlw ((D'989' & H'ff00') >> 8) movwf ACCbHI call D_sub ;accb = accB - accA movlw 0 btfss ACCbHI,7 ; test for minus result goto main02 ; very small error bcf PORTB,0 ; small error led on call loadacc ; accB = error constant movlw D'991' & H'ff' movwf ACCbLO movlw ((D'991' & H'ff00') >> 8) movwf ACCbHI call D_sub ;accb = accB - accA movlw 1 btfss ACCbHI,7 ; test for minus result goto main02 ; small error bcf PORTB,3 ; med error led on call loadacc ; accB = error constant movlw D'993' & H'ff' movwf ACCbLO movlw ((D'993' & H'ff00') >> 8) movwf ACCbHI call D_sub ;accb = accB - accA movlw 16 btfss ACCbHI,7 ; test for minus result goto main02 ; small error bcf PORTB,4 ; med error led on call loadacc ; accB = largest error constant movlw D'995' & H'ff' movwf ACCbLO movlw ((D'995' & H'ff00') >> 8) movwf ACCbHI call D_sub ;accb = accB - accA movlw 96 btfss ACCbHI,7 ; test for minus result goto main02 ; small error bcf PORTB,5 ; large error led on movlw 192 ; big correction for power ups ; update dac by w amount main02 incf flasher,f ; count each update cycle clrf gps_err ; assume no error on dac o/p btfsc ser_b61,7 call dac_inc btfss ser_b61,7 call dac_dec btfss gps_err,0 goto main ;discard rest of packet ; get here when dac inc or dec has hit a limit ; 4 leds have already been set with error magnitude ; on alternate cycles, we clear them to flash display btfsc flasher,0 call clrled goto main ; routine to turn off all 4 error magnitude display leds clrled bsf PORTB,0 ; led off nop bsf PORTB,3 ; led off nop bsf PORTB,4 ; led off nop bsf PORTB,5 ; led off return ; setup accummulator for subtract ; accA = exponent loadacc movf exp_l,w movwf ACCaLO movf exp_h,w movwf ACCaHI return ; *********************************************************************** ; ; INIT_UART - Initialises UART ; enables recevier and transmitter ; Make sure to be at bank0 uart_baud(9600) init_uart ; make sure pins are setup before calling this routine ; TRISC:6 and TRISC:7 must be set ( as for output, but operates as input/output ) ; furthermore its advised that interrupts are disabled during this routine ; setup baudrate MOVLW SPBRG ; get adress for serial baud reg MOVWF FSR ; setup fsr MOVLW val_spbrg MOVWF INDF ; and store it ; enable transmitter MOVLW TXSTA ; get adress for serial enable reg MOVWF FSR ; setup fsr MOVLW val_txsta; preset enable transmitter and high speed mode MOVWF INDF ; and set it ; enable recevier MOVLW (1< ACCb(16 bits) ; (a) Load the 1st operand in location ACCaLO & ACCaHI ( 16 bits ) ; (b) Load the 2nd operand in location ACCbLO & ACCbHI ( 16 bits ) ; (c) CALL D_add ; (d) The result is in location ACCbLO & ACCbHI ( 16 bits ) ; ; Performance : ; Program Memory : 07 ; Clock Cycles : 08 ;*******************************************************************; ; Subtraction : ACCb(16 bits) - ACCa(16 bits) -> ACCb(16 bits) ; (a) Load the 1st operand in location ACCaLO & ACCaHI ( 16 bits ) ; (b) Load the 2nd operand in location ACCbLO & ACCbHI ( 16 bits ) ; (c) CALL D_sub ; (d) The result is in location ACCbLO & ACCbHI ( 16 bits ) ; ; Performance : ; Program Memory : 14 ; Clock Cycles : 17 ; ; ; Program: DBL_ADD.ASM ; Revision Date: ; 1-13-97 Compatibility with MPASMWIN 1.40 ; ;*******************************************************************; ; ;******************************************************************* ; Double Precision Subtraction ( ACCb - ACCa -> ACCb ) ; D_sub call neg_A ; At first negate ACCa; Then add ; ;******************************************************************* ; Double Precision Addition ( ACCb + ACCa -> ACCb ) ; D_add movf ACCaLO,W addwf ACCbLO, F ;add lsb btfsc STATUS,C ;add in carry incf ACCbHI, F movf ACCaHI,W addwf ACCbHI, F ;add msb retlw 0 ; ; neg_A comf ACCaLO, F ; negate ACCa ( -ACCa -> ACCa ) incf ACCaLO, F btfsc STATUS,Z decf ACCaHI, F comf ACCaHI, F retlw 0 END ; directive 'end of program'