; Filename: FSK_TX.SRC ; Author: Stephen Holland ; Applications Engineer ; Scenix Semiconductor Inc. ; Revision: 1.0 ; Date: July 05, 1998 ; Part: SX28AC rev. 2.5 ; Freq: 50Mhz ; Compiled using Parallax SX-Key software v0.8 ; ; *This virtual peripheral relies on an external RC filter to generate complete ; FSK signal. ; ; ; Using a PC terminal program, all data received by the UART is sent out via ; FSK transmission ; device pins28,pages4,banks8,oschs device turbo,stackx,optionx,carryx id 'FSK_TX' reset reset_entry ; ; ; Equates ; rx_pin = ra.1 tx_pin = ra.2 pwm0_pin = ra.0 ; ; ; Variables ; org 8 temp ds 1 byte ds 1 string ds 1 org 10h ;bank0 variables timers = $ ;timer timer_accl ds 1 timer_acch ds 1 timer_flag ds 1 bit_cnt ds 1 org 30h ;bank1 variables serial = $ tx_high ds 1 ;tx tx_low ds 1 tx_count ds 1 tx_divide ds 1 tx_flag ds 1 ;flag-byte ;bit 0, busy transmitting, 0=no, 1=yes tx_dly_count ds 1 rx_count ds 1 ;rx rx_divide ds 1 rx_byte ds 1 rx_flag ds 1 rx_dly_count ds 1 org 50h ;bank3 variables pwm = $ pwm_duty_1 ds 1 pwm_period_1 ds 1 lo_or_hi ds 1 counter_fsk ds 1 row ds 1 col ds 1 FSK_trm_byte ds 1 ; ; ; Interrupt routine - virtual peripherals ; org 0 interrupt ;3 it takes 3 cycles to get an interrupt bank timers ;1 ;timer stc ;1 set carry add timer_accl,#1 ;2 add timer_accl+carry(=1) sc jmp :timer_out add timer_acch,#0 snc ;1 setb timer_flag.0 ;1 :timer_out ;=7 ;********D/A CONVERSIONS************* da_conv bank pwm ;1 dec pwm_duty_1 ;1 decrement port_duty movb pwm0_pin,/pwm_duty_1.7 ;4 move complement of most significant bit to output decsz pwm_period_1 ;1 jmp da_conv_out ;3 mov pwm_duty_1,#5 ;2 jb lo_or_hi.0,:period_1200 ;1 hi for 1200, lo for 2200 :period_2200 mov pwm_period_1,#10 ;1 this is for phase coherence in freq shifts jmp :continue :period_1200 mov pwm_period_1,#9 ;2 :continue make_fsk make1200 csae counter_fsk,#end1200 ;1 take new table value jmp :continue ;1 mov counter_fsk,#sine1200 ;1 reload table-counter :continue mov w,counter_fsk ;1 mov m,#6 ;1 set page iread ;1 get table_data mov m,#$F ;1 mov pwm_duty_1,w ;1 = 21 inc counter_fsk ;1 sb lo_or_hi.0 ;1 hi for 1200, lo for 2200 inc counter_fsk ;1 this is for phase coherence in freq shifts jmp da_conv_out da_conv_out ;********SERIAL COMMUNICATIONS************* :ser_comm bank serial ;1 inc tx_dly_count ;1 inc rx_dly_count ;1 snb rx_dly_count.2 ;1 divide by 4 jmp :tst_rx ;3 sb tx_dly_count.4 ;1 = 8 ;divide by 16 jmp interrupt_out ;3 :tst_tx clr tx_dly_count ;1 jnb tx_flag.0,interrupt_out ;2 test tx_count ;1 busy? clc ;1 ready stop bit snz ;1 clrb tx_flag.0 ;1 sz ;1 if busy, shift bits rr tx_high ;1 sz ;1 rr tx_low ;1 sz ;1 ;if busy, dec counter dec tx_count ;1 movb tx_pin,/tx_low.6 ;4 =18 ;output next bit jmp interrupt_out ;3 :tst_rx clr rx_dly_count ;1 movb c,rx_pin ;4 ;serial receive test rx_count ;1 ;waiting for stop bit? jnz :rxbit ;3,2 ;if not, :bit mov w,#9 ;1 ;in case start, ready 9 bits sc ;1 ;if start, set rx_count mov rx_count,w ;1 mov rx_divide,#7 ;2 ;ready 1.5 bit periods :rxbit djnz rx_divide,:rxdone ;3,2 ;8th time through? setb rx_divide.2 ;1 ;yes, ready 1 bit period dec rx_count ;1 ;last bit? sz ;1 ;if not, save bit rr rx_byte ;1 snz ;1 ;if so, set flag setb rx_flag.1 ;1 =23 :rxdone interrupt_out mov w,#-163 ;1 ;interrupt every 159 clocks retiw ;3 ; ; ; Reset entry ; reset_entry mov ra,#%0110 ;init ra mov !ra,#%0011 ;Set ra data direction register mov m,#$F bank serial inc rx_dly_count ;just to create a slight time-shift clr fsr ;reset all ram banks :loop setb fsr.4 clr ind ijnz fsr,:loop bank pwm ;adc set speed/resolution mov pwm_period_1,#9 mov pwm_duty_1,#5 bank serial clr bit_cnt mov !option,#%10011111 ;enable rtcc interrupt ; ;************************************************************* ; Main ;************************************************************* ; ; ; Terminal - main loop ; main mov w,#_hello ;send hello string page send_string call send_string mov w,#_prompt ;send prompt string page send_string call send_string main_loop page get_byte call get_byte ; This is where the line could be tested if it clear to send, if not then jump to :send_later bank serial jnb rx_flag.7,:send_later ;If bit not set then nothing to send page FSK_send call FSK_send :send_later ; This is where a FSK_receive function would be called jmp main_loop ;************************************************************* ;************************************************************* ; Subroutines ;************************************************************* org $200 ;************************************************************* ; Jump table for page 1 ;************************************************************* FSK_send jmp FSK_send_byte FSK_send_return retp ;************************************************************* ; ; Get byte via serial port ; get_byte bank serial sb rx_flag.1 retp clrb rx_flag.1 setb rx_flag.7 ;Tell FSK module to send mov w,rx_byte ;followed by send_byte bank pwm mov FSK_trm_byte,w mov w,#_sending ;send 'sending' string page send_string call send_string bank pwm mov w,FSK_trm_byte call send_byte mov w,#_prompt ;send prompt string page send_string call send_string retp ; ; Send byte via serial port ; send_byte bank serial :wait test tx_count ;wait for not busy jnz :wait not w ;ready bits mov tx_high,w setb tx_low.7 mov tx_count,#10 ;1 start + 8 data + 1 stop bit setb tx_flag.0 retp ; ; ; Send string at w ; send_string mov string,w ;send string at w :loop mov w,string ;read chr at w mov m,#1 iread mov m,#$F test w ;if 0, exit snz retp page send_byte call send_byte ;not 0, send chr inc string ;next chr jmp :loop ; ; ; Make byte uppercase ; uppercase csae byte,#'a' ret sub byte,#'a'-'A' ret ;************************************************************* FSK_send_byte setb ra.3 ;Enable output mov !ra,#%0010 ;Enable pwm output ; This is where channel seizure or handshaking generation would be inserted. bank pwm setb lo_or_hi.0 ;Set PWM to transmit 1200Hz for start bit bank timers mov !option,#%11011111 ;disable rtcc interrupt mov timer_accl,#$5d ;1250uS mov timer_acch,#$fd ;--//-- mov !option,#%10011111 ;enable rtcc interrupt clrb timer_flag.0 ;Clear overflow-flag jnb timer_flag.0,$ ;Is overflow-flag set? mov bit_cnt,#8 ;Initialize bit_cnt :next_bit bank pwm jnb FSK_trm_byte.0,:set_2200_pwm :set_1200_pwm setb lo_or_hi.0 ;Set PWM to transmit 1200Hz jmp :set_timer_833u :set_2200_pwm clrb lo_or_hi.0 ;Set PWM to transmit 2200Hz :set_timer_833u bank timers mov !option,#%11011111 ;disable rtcc interrupt mov timer_accl,#$00 ;833uS mov timer_acch,#$fe ;--//-- mov !option,#%10011111 ;enable rtcc interrupt clrb timer_flag.0 ;Clear overflow-flag jnb timer_flag.0,$ ;Is overflow-flag set? bank pwm rr FSK_trm_byte bank timers djnz bit_cnt,:next_bit bank pwm clrb lo_or_hi.0 ;Set PWM to transmit 2200Hz for stop bit bank timers mov !option,#%11011111 ;disable rtcc interrupt mov timer_accl,#$00 ;833uS mov timer_acch,#$fe ;--//-- mov !option,#%10011111 ;enable rtcc interrupt clrb timer_flag.0 ;Clear overflow-flag jnb timer_flag.0,$ ;Is overflow-flag set? :FSK_transmit_out mov !ra,#%0011 ;Disable pwm output clrb ra.3 ;Disable output bank serial clrb rx_flag.7 jmp FSK_send_return ;************************************************************* ;************************************************************* ; org $1a0 ; ; Data ; _hello dw 13,10,13,10,'SX Modem Demo...',13,10,0 _cr dw 13,10,0 _prompt dw 13,10,'>',0 _sending dw 13,10,'Sending...',32,0 _hex dw '0123456789ABCDEF' org $600 sine1200 = $ DW 5 ; 1 DW 7 ; 2 DW 8 ; 3 DW 8 ; 4 DW 9 ; 5 DW 9 ; 6 DW 10 ; 7 DW 9 ; 8 DW 9 ; 9 DW 8 ;10 DW 8 ;11 DW 7 ;12 DW 6 ;13 DW 5 ;14 DW 3 ;15 DW 2 ;16 DW 1 ;17 DW 1 ;18 DW 0 ;19 DW 0 ;20 DW 0 ;21 DW 0 ;22 DW 0 ;23 DW 1 ;24 DW 1 ;25 DW 2 ;26 DW 3 ;27 end1200 = $ DW 4 ;28
| file: /Techref/scenix/lib/io/dev/modem/fsk.src, 9KB, , updated: 1999/2/20 11:23, local time: 2024/11/14 23:39,
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