; *****************************************************************************************
; Copyright © [01/26/1999] Scenix Semiconductor, Inc. All rights reserved.
;
; Scenix Semiconductor, Inc. assumes no responsibility or liability for
; the use of this [product, application, software, any of these products].
; Scenix Semiconductor conveys no license, implicitly or otherwise, under
; any intellectual property rights.
; Information contained in this publication regarding (e.g.: application,
; implementation) and the like is intended through suggestion only and may
; be superseded by updates. Scenix Semiconductor makes no representation
; or warranties with respect to the accuracy or use of these information,
; or infringement of patents arising from such use or otherwise.
;*****************************************************************************************
;
; Filename: simple_fsk_rcv_1_10.src
;
; Authors: Chris Fogelklou
; Applications Engineer
; Scenix, Inc.
;
; Revision: 1.10
;
; Part: SX28AC datecode 9929AA
;
; Freq: 50Mhz
;
; Compiled using Parallax SX-Key software v1.07 and SASM 1.40
;
; Date Written: January 25, 1999
;
; Last Revised: November 17, 1999
;
; Program Description: This is simple software to demonstrate the concept of
; converting an incoming frequency to a data train. This
; program simply watches the incoming frequency and outputs
; a high or a low to the RS-232 TX pin. For this reason, the
; PC that the board is connected to must be set to the desired
; baud rate. Example: If a 300,N,8,1 settings are desired,
; simply set the PC's terminal program to these settings and
; the SX modem will act as a simple frequency-voltage converter,
; translating the incoming frequency (1300Hz and 2100Hz) to
; an output voltage which the computer will receive as a 300,N,8,1
; data packet. Once the modem is connected, simply press a key
; on the keyboard to get it to pick up and begin receiving.
;
; Disclaimer: This program is simplified... It is just
; for demo purposes, to show the power and
; simplicity of Virtual Peripherals for telephony
; applications. An actual modem would need a
; more complex algorithm (See the V.23 Modem Appnote)
; to achieve sufficient error response.
;
; Note: This program works only with an accurate Oscillator.
; The SX-ISD's Oscillator is not accurate enough to
; produce error-free results. The XTAL on the Scenix
; Demo boards produced better results.
;
; INPUTS:
; FSK input on fsk_rx_pin (rb.1) (Signal must be passed through comparator/zero-cross
; circuitry.)
; RS-232 input on rx_pin (ra.1)
;
; OUTPUTS:
; Received RS-232 characters on tx_pin (ra.2)
; LED flashes while receiving on led_pin (rb.0)
;
; Revision History: 1.0 Drew out the FSK receive code from the rest of the code
; surrounding it in the old modem demo software and implemented
; it as a module by itself (December 17, 1998)
; 1.01 Added more documentation to the software for web-posting.
; (January 25, 1999)
; 1.02 Added support for rev 1.4 boards (2/23/99)
; 1.10 Updated the program for the SASM assembler
;
; RESOURCES:
; Program memory: 91 Words
; Data memory: 2 1/8 bytes
;*****************************************************************************************
;*****************************************************************************************
; Target SX
; Uncomment one of the following lines to choose the SX18AC, SX20AC, SX28AC, SX48BD/ES,
; SX48BD, SX52BD/ES or SX52BD. For SX48BD/ES and SX52BD/ES, uncomment both defines,
; SX48_52 and SX48_52_ES.
;*****************************************************************************************
;SX18_20
SX28
;SX48_52
;SX48_52_ES
;*****************************************************************************************
; Assembler Used
; Uncomment the following line if using the Parallax SX-Key assembler. SASM assembler
; enabled by default.
;*****************************************************************************************
SX_Key
;*********************************************************************************
; Assembler directives:
; high speed external osc, turbo mode, 8-level stack, and extended option reg.
;
; SX18/20/28 - 4 pages of program memory and 8 banks of RAM enabled by default.
; SX48/52 - 8 pages of program memory and 16 banks of RAM enabled by default.
;
;*********************************************************************************
IFDEF SX_Key ;SX-Key Directives
IFDEF SX18_20 ;SX18AC or SX20AC device directives for SX-Key
device SX18L,oschs2,turbo,stackx_optionx
ENDIF
IFDEF SX28 ;SX28AC device directives for SX-Key
device SX28L,oschs2,turbo,stackx_optionx
ENDIF
IFDEF SX48_52_ES ;SX48BD/ES or SX52BD/ES device directives for SX-Key
device oschs,turbo,stackx,optionx
ELSE
IFDEF SX48_52 ;SX48/52/BD device directives for SX-Key
device oschs2
ENDIF
ENDIF
freq 50_000_000
ELSE ;SASM Directives
IFDEF SX18_20 ;SX18AC or SX20AC device directives for SASM
device SX18,oschs2,turbo,stackx,optionx
ENDIF
IFDEF SX28 ;SX28AC device directives for SASM
device SX28,oschs2,turbo,stackx,optionx
ENDIF
IFDEF SX48_52_ES ;SX48BD/ES or SX52BD/ES device directives for SASM
device SX52,oschs,turbo,stackx,optionx
ELSE
IFDEF SX48_52 ;SX48BD or SX52BD device directives for SASM
device SX52,oschs2
ENDIF
ENDIF
ENDIF
id 'SFSKRX11' ;
reset reset_entry ; set reset vector
;*****************************************************************************************
; Macros
;*****************************************************************************************
;*********************************************************************************
; Macro: _bank
; Sets the bank appropriately for all revisions of SX.
;
; This is required since the bank instruction has only a 3-bit operand, it cannot
; be used to access all 16 banks of the SX48/52. For this reason FSR.4 (for SX48/52BD/ES)
; or FSR.7 (SX48/52bd production release) needs to be set appropriately, depending
; on the bank address being accessed. This macro fixes this.
;
; So, instead of using the bank instruction to switch between banks, use _bank instead.
;
;*********************************************************************************
_bank macro 1
bank \1
IFDEF SX48_52
IFDEF SX48_52_ES
IF \1 & %00010000 ;SX48BD/ES and SX52BD/ES (engineering sample) bank instruction
setb fsr.4 ;modifies FSR bits 5,6 and 7. FSR.4 needs to be set by software.
ENDIF
ELSE
IF \1 & %10000000 ;SX48BD and SX52BD (production release) bank instruction
setb fsr.7 ;modifies FSR bits 4,5 and 6. FSR.7 needs to be set by software.
ELSE
clrb fsr.7
ENDIF
ENDIF
ENDIF
endm
;*********************************************************************************
; Macro: _mode
; Sets the MODE register appropriately for all revisions of SX.
;
; This is required since the MODE (or MOV M,#) instruction has only a 4-bit operand.
; The SX18/20/28AC use only 4 bits of the MODE register, however the SX48/52BD have
; the added ability of reading or writing some of the MODE registers, and therefore use
; 5-bits of the MODE register. The MOV M,W instruction modifies all 8-bits of the
; MODE register, so this instruction must be used on the SX48/52BD to make sure the MODE
; register is written with the correct value. This macro fixes this.
;
; So, instead of using the MODE or MOV M,# instructions to load the M register, use
; _mode instead.
;
;*********************************************************************************
_mode macro 1
IFDEF SX48_52
mov w,#\1 ;loads the M register correctly for the SX48BD and SX52BD
mov m,w
ELSE
mov m,#\1 ;loads the M register correctly for the SX18AC, SX20AC
;and SX28AC
ENDIF
endm
;*****************************************************************************************
; Data Memory address definitions
; These definitions ensure the proper address is used for banks 0 - 7 for 2K SX devices
; (SX18/20/28) and 4K SX devices (SX48/52).
;*****************************************************************************************
IFDEF SX48_52
global_org = $0A
bank0_org = $00
bank1_org = $10
bank2_org = $20
bank3_org = $30
bank4_org = $40
bank5_org = $50
bank6_org = $60
bank7_org = $70
ELSE
global_org = $08
bank0_org = $10
bank1_org = $30
bank2_org = $50
bank3_org = $70
bank4_org = $90
bank5_org = $B0
bank6_org = $D0
bank7_org = $F0
ENDIF
;*****************************************************************************************
; Global Register definitions
; NOTE: Global data memory starts at $0A on SX48/52 and $08 on SX18/20/28.
;*****************************************************************************************
org global_org
function_temp equ global_org+1
global_temp equ global_org+2
;*****************************************************************************************
; RAM Bank Register definitions
;*****************************************************************************************
;*********************************************************************************
; Bank 0
;*********************************************************************************
org bank0_org
bank0 = $
flags ds 1
fsk_rx_en equ flags.0 ; Enables the FSK receiver.
;*********************************************************************************
; Bank 1
;*********************************************************************************
org bank1_org
bank1 = $
fsk_receive_bank = $
fsk_trans_count ds 1 ; This register counts the number of counts
; between transitions at the pin
rb_past_state ds 1 ; This register keeps track of the previous
; state of port RB, to watch for transitions
;*********************************************************************************
; Bank 2
;*********************************************************************************
org bank2_org
bank2 = $
;*********************************************************************************
; Bank 3
;*********************************************************************************
org bank3_org
bank3 = $
;*********************************************************************************
; Bank 4
;*********************************************************************************
org bank4_org
bank4 = $
;*********************************************************************************
; Bank 5
;*********************************************************************************
org bank5_org
bank5 = $
;*********************************************************************************
; Bank 6
;*********************************************************************************
org bank6_org
bank6 = $
;*********************************************************************************
; Bank 7
;*********************************************************************************
org bank7_org
bank7 = $
IFDEF SX48_52
;*********************************************************************************
; Bank 8
;*********************************************************************************
org $80 ;bank 8 address on SX52
bank8 = $
;*********************************************************************************
; Bank 9
;*********************************************************************************
org $90 ;bank 9 address on SX52
bank9 = $
;*********************************************************************************
; Bank A
;*********************************************************************************
org $A0 ;bank A address on SX52
bankA = $
;*********************************************************************************
; Bank B
;*********************************************************************************
org $B0 ;bank B address on SX52
bankB = $
;*********************************************************************************
; Bank C
;*********************************************************************************
org $C0 ;bank C address on SX52
bankC = $
;*********************************************************************************
; Bank D
;*********************************************************************************
org $D0 ;bank D address on SX52
bankD = $
;*********************************************************************************
; Bank E
;*********************************************************************************
org $E0 ;bank E address on SX52
bankE = $
;*********************************************************************************
; Bank F
;*********************************************************************************
org $F0 ;bank F address on SX52
bankF = $
ENDIF
;*********************************************************************************
; Pin Definitions (These pins are for use with the Scenix Modem Demo Board,
; Rev. 1.2)
;*********************************************************************************
PDM_pin equ ra.0 ; D/A output pin
rx_pin equ ra.1 ; RS-232 reception pin
tx_pin equ ra.2 ; RS-232 transmission pin
nothing equ ra.3 ; N/C
RA_latch equ %11111111 ;SX18/20/28/48/52 port A latch init
RA_DDIR equ %11111011 ;SX18/20/28/48/52 port A DDIR value
RA_LVL equ %00000000 ;SX18/20/28/48/52 port A LVL value
RA_PLP equ %11111111 ;SX18/20/28/48/52 port A PLP value
led_pin equ rb.0 ; LED pin
rxa_pin equ rb.1 ; FSK receive pin
cntrl_1 equ rb.2 ; drive cntrl_1 low to disable the output of the LPF
ring equ rb.3 ; ring detection pin
hook equ rb.4 ; drive hook low to go off-hook
cntrl_3 equ rb.5 ; drive cntrl_3 low to disable the output of the HPF
rts equ rb.6 ; indicates to the SX that the PC wants to transmit data
cts equ rb.7 ; indicates to the PC that the SX is ready to receive data
RB_latch equ %11011011 ;SX18/20/28/48/52 port B latch init
RB_DDIR equ %01101010 ;SX18/20/28/48/52 port B DDIR value
RB_ST equ %11111111 ;SX18/20/28/48/52 port B ST value
RB_LVL equ %00000000 ;SX18/20/28/48/52 port B LVL value
RB_PLP equ %11111111 ;SX18/20/28/48/52 port B PLP value
dtmf_in_pin equ rc.0 ; DTMF input pin
dtmf_fdbk_pin equ rc.1 ; Negative feedback output for DTMF input
AtoD_in_pin equ rc.2 ; A/D input pin
AtoD_fdbk_pin equ rc.3 ; Negative feedback for A/D input
imp_450_pin equ rc.4 ; Set to an output to set hybrid for 450ohm line impedance. Tristate otherwise.
imp_600_pin equ rc.5 ; Set to an output to set hybrid for 600ohm line impedance. Tristate otherwise.
imp_750_pin equ rc.6 ; Set to an output to set hybrid for 750ohm line impedance. Tristate otherwise.
imp_900_pin equ rc.7 ; Set to an output to set hybrid for 900ohm line impedance. Tristate otherwise.
RC_latch equ %00001111 ;SX18/20/28/48/52 port C latch init
RC_DDIR equ %11010101 ;SX18/20/28/48/52 port C DDIR value
RC_ST equ %11111111 ;SX18/20/28/48/52 port C ST value
RC_LVL equ %00000000 ;SX18/20/28/48/52 port C LVL value
RC_PLP equ %11111111 ;SX18/20/28/48/52 port C PLP value
IFDEF SX48_52 ;SX48BD/52BD Port initialization values
RD_latch equ %00000000 ;SX48/52 port D latch init
RD_DDIR equ %11111111 ;SX48/52 port D DDIR value
RD_ST equ %11111111 ;SX48/52 port D ST value
RD_LVL equ %00000000 ;SX48/52 port D LVL value
RD_PLP equ %11111111 ;SX48/52 port D PLP value
RE_latch equ %00000000 ;SX48/52 port E latch init
RE_DDIR equ %11111111 ;SX48/52 port E DDIR value
RE_ST equ %11111111 ;SX48/52 port E ST value
RE_LVL equ %00000000 ;SX48/52 port E LVL value
RE_PLP equ %11111111 ;SX48/52 port E PLP value
ENDIF
;*****************************************************************************************
; Program constants
;*****************************************************************************************
;******************************************************************************
; Equates for FSK reception
;******************************************************************************
glitch_th equ 20 ; The threshold which defines a glitch (small spike which should be ignored)
low_count_error_th equ 40 ; The lowest count allowed for a high frequency
low_high_th equ 95 ; The lowest count allowed for a low frequency
high_count_error_th equ 140 ; The highest count allowed for a low frequency
int_period equ 163 ;RTCC Interrupt rate
IFDEF SX48_52
;*********************************************************************************
; SX48BD/52BD Mode addresses
; *On SX48BD/52BD, most registers addressed via mode are read and write, with the
; exception of CMP and WKPND which do an exchange with W.
;*********************************************************************************
; Timer (read) addresses
TCPL_R equ $02 ;Read Timer Capture register low byte
TCPH_R equ $02 ;Read Timer Capture register high byte
TR2CML_R equ $02 ;Read Timer R2 low byte
TR2CMH_R equ $03 ;Read Timer R2 high byte
TR1CML_R equ $04 ;Read Timer R1 low byte
TR1CMH_R equ $05 ;Read Timer R1 high byte
TCNTB_R equ $06 ;Read Timer control register B
TCNTA_R equ $07 ;Read Timer control register A
; Exchange addresses
CMP equ $08 ;Exchange Comparator enable/status register with W
WKPND equ $09 ;Exchange MIWU/RB Interrupts pending with W
; Port setup (read) addresses
WKED_R equ $0A ;Read MIWU/RB Interrupt edge setup, 0 = falling, 1 = rising
WKEN_R equ $0B ;Read MIWU/RB Interrupt edge setup, 0 = enabled, 1 = disabled
ST_R equ $0C ;Read Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
LVL_R equ $0D ;Read Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
PLP_R equ $0E ;Read Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
DDIR_R equ $0F ;Read Port Direction
; Timer (write) addresses
TR2CML_W equ $12 ;Write Timer R2 low byte
TR2CMH_W equ $13 ;Write Timer R2 high byte
TR1CML_W equ $14 ;Write Timer R1 low byte
TR1CMH_W equ $15 ;Write Timer R1 high byte
TCNTB_W equ $16 ;Write Timer control register B
TCNTA_W equ $17 ;Write Timer control register A
; Port setup (write) addresses
WKED_W equ $1A ;Write MIWU/RB Interrupt edge setup, 0 = falling, 1 = rising
WKEN_W equ $1B ;Write MIWU/RB Interrupt edge setup, 0 = enabled, 1 = disabled
ST_W equ $1C ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
LVL_W equ $1D ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
PLP_W equ $1E ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
DDIR_W equ $1F ;Write Port Direction
ELSE
;*********************************************************************************
; SX18AC/20AC/28AC Mode addresses
; *On SX18/20/28, all registers addressed via mode are write only, with the exception of
; CMP and WKPND which do an exchange with W.
;*********************************************************************************
; Exchange addresses
CMP equ $08 ;Exchange Comparator enable/status register with W
WKPND equ $09 ;Exchange MIWU/RB Interrupts pending with W
; Port setup (read) addresses
WKED_W equ $0A ;Write MIWU/RB Interrupt edge setup, 0 = falling, 1 = rising
WKEN_W equ $0B ;Write MIWU/RB Interrupt edge setup, 0 = enabled, 1 = disabled
ST_W equ $0C ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
LVL_W equ $0D ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
PLP_W equ $0E ;Write Port Schmitt Trigger setup, 0 = enabled, 1 = disabled
DDIR_W equ $0F ;Write Port Direction
ENDIF
;*****************************************************************************************
; Interrupt Service Routine
;*****************************************************************************************
; Note: The interrupt code must always originate at address $0.
;
; Interrupt Frequency = (Cycle Frequency / -(retiw value)) For example:
; With a retiw value of -163 and an oscillator frequency of 50MHz, this
; code runs every 3.26us.
;*****************************************************************************************
org $0
interrupt ;3
;*********************************************************************************
; Virtual Peripheral: FSK Detection (Simple)
;
;
; Input variable(s): fsk_rx_en: Enables/Disables this routine
; RB.1: FSK Input on this port pin.
; Output variable(s): Sets/Clears the LED_pin and the tx_pin, depending on
; the current input frequency
; Variable(s) affected: fsk_trans_count, rb_past_state
; Flag(s) affected: None
; Variable Length?: Yes.
;*********************************************************************************
jnb fsk_rx_en,fsk_rx_out ; jump out if the FSK receiver is not enabled
FSK_RECEIVE
bank fsk_receive_bank ; switch to fsk_receive_bank of RAM
add fsk_trans_count,#1 ; Regardless of what is going on, increment the
snc ; transition timer. These get cleared when a transition
jmp :error ; takes place.
cjb fsk_trans_count,#low_high_th,:fsk_timer_out ; as soon as it takes longer than 95 counts
setb tx_pin ; to transition, this must be a low frequency
clrb LED_pin ; If a high is being sent, clear the LED
:fsk_timer_out
mov w,rb
and w,#%00000010 ; get the current state of rb.
xor w,rb_past_state ; compare it with the previous state of the pin
jz fsk_rx_out ; if there was no change, then jump out, there is nothing to do.
; Now it is time to determine if the transition that took place indicates a bit was received
; (it must be within some thresholds... below 20, ignore it, below 40, what???,
; below 95, high frequency, below 140, low frequency (already set), above 140,
; what???)
cjb fsk_trans_count,#glitch_th,:glitch_so_ignore ; pulse was below specs, ignore it... probably noise
cjb fsk_trans_count,#low_count_error_th,:error ; pulse was not a glitch but wasn't long enough to mean anything... huh?
cjb fsk_trans_count,#low_high_th,:high_frequency ; pulse was within specs for a high frequency...
cjb fsk_trans_count,#high_count_error_th,:fsk_receive_done ; pulse was within specs for a low frequency (don't do anything)
jmp :error ; pulse was too long to mean anything, so do nothing.
:high_frequency ; a high frequency corresponds to low data.
clrb tx_pin
setb LED_pin ; set the LED to indicate a LOW is being sent.
jmp :fsk_receive_done
:error
;--------------- PUT ERROR HANDLING CODE IN HERE -----------------
:fsk_receive_done
clr fsk_trans_count ; clear the bit counter.
:glitch_so_ignore ; don't clear the counter if the data was a glitch
mov w,rb ; save the new state of RB.
and w,#%00000010
mov rb_past_state,w
fsk_rx_out
;*********************************************************************************
; Set Interrupt Rate
;*********************************************************************************
isr_end mov w,#-int_period ;refresh RTCC on return
retiw ;return from the interrupt
; = 1/(int_period*RTCC prescaler*1/50MHz)
; = 1/(163*1*20ns) = 1/3.26us = 306.7kHz
;*****************************************************************************************
; End of the Interrupt Service Routine
;*****************************************************************************************
;*****************************************************************************************
; RESET VECTOR
;*****************************************************************************************
;*********************************************************************************
; Program execution begins here on power-up or after a reset
;*********************************************************************************
reset_entry jmp @_reset_entry ; Go to the location in the last page where the
; main program is.
;*****************************************************************************************
org $200
;*****************************************************************************************
; Jump table for page 1
; Enables CALLs to functions in the second half of the page
;*****************************************************************************************
;function_label_2 jmp function_label_2_
;*****************************************************************************************
; Subroutines
;*****************************************************************************************
;*********************************************************************************
; Function:
;
; Inputs:
;
; Outputs:
;
; Registers affected:
;
; Functions Called:
;
;*********************************************************************************
;function_label
; retp
;*********************************************************************************
; Function:
;
; Inputs:
;
; Outputs:
;
; Registers affected:
;
; Functions Called:
;
;*********************************************************************************
;function_label_1
; retp
;*********************************************************************************
; Function:
;
; Inputs:
;
; Outputs:
;
; Registers affected:
;
; Functions Called:
;
;*********************************************************************************
;function_label_2_
; retp
;*****************************************************************************************
org $400
;*****************************************************************************************
;*****************************************************************************************
org $600
;*****************************************************************************************
;*****************************************************************************************
; RESET VECTOR
;*****************************************************************************************
;*********************************************************************************
; Program execution begins here on power-up or after a reset
;*********************************************************************************
_reset_entry
;*********************************************************************************
; Initialise all port configuration
;*********************************************************************************
_mode ST_W ;point MODE to write ST register
mov w,#RB_ST ;Setup RB Schmitt Trigger, 0 = enabled, 1 = disabled
mov !rb,w
mov w,#RC_ST ;Setup RC Schmitt Trigger, 0 = enabled, 1 = disabled
mov !rc,w
IFDEF SX48_52
mov w,#RD_ST ;Setup RD Schmitt Trigger, 0 = enabled, 1 = disabled
mov !rd,w
mov w,#RE_ST ;Setup RE Schmitt Trigger, 0 = enabled, 1 = disabled
mov !re,w
ENDIF
_mode LVL_W ;point MODE to write LVL register
mov w,#RA_LVL ;Setup RA CMOS or TTL levels, 0 = TTL, 1 = CMOS
mov !ra,w
mov w,#RB_LVL ;Setup RB CMOS or TTL levels, 0 = TTL, 1 = CMOS
mov !rb,w
mov w,#RC_LVL ;Setup RC CMOS or TTL levels, 0 = TTL, 1 = CMOS
mov !rc,w
IFDEF SX48_52
mov w,#RD_LVL ;Setup RD CMOS or TTL levels, 0 = TTL, 1 = CMOS
mov !rd,w
mov w,#RE_LVL ;Setup RE CMOS or TTL levels, 0 = TTL, 1 = CMOS
mov !re,w
ENDIF
_mode PLP_W ;point MODE to write PLP register
mov w,#RA_PLP ;Setup RA Weak Pull-up, 0 = enabled, 1 = disabled
mov !ra,w
mov w,#RB_PLP ;Setup RB Weak Pull-up, 0 = enabled, 1 = disabled
mov !rb,w
mov w,#RC_PLP ;Setup RC Weak Pull-up, 0 = enabled, 1 = disabled
mov !rc,w
IFDEF SX48_52
mov w,#RD_PLP ;Setup RD Weak Pull-up, 0 = enabled, 1 = disabled
mov !rd,w
mov w,#RE_PLP ;Setup RE Weak Pull-up, 0 = enabled, 1 = disabled
mov !re,w
ENDIF
_mode DDIR_W ;point MODE to write DDIR register
mov w,#RA_DDIR ;Setup RA Direction register, 0 = output, 1 = input
mov !ra,w
mov w,#RB_DDIR ;Setup RB Direction register, 0 = output, 1 = input
mov !rb,w
mov w,#RC_DDIR ;Setup RC Direction register, 0 = output, 1 = input
mov !rc,w
IFDEF SX48_52
mov w,#RD_DDIR ;Setup RD Direction register, 0 = output, 1 = input
mov !rd,w
mov w,#RE_DDIR ;Setup RE Direction register, 0 = output, 1 = input
mov !re,w
ENDIF
mov w,#RA_latch ;Initialize RA data latch
mov ra,w
mov w,#RB_latch ;Initialize RB data latch
mov rb,w
mov w,#RC_latch ;Initialize RC data latch
mov rc,w
IFDEF SX48_52
mov w,#RD_latch ;Initialize RD data latch
mov rd,w
mov w,#RE_latch ;Initialize RE data latch
mov re,w
ENDIF
;*********************************************************************************
; Clear all Data RAM locations
;*********************************************************************************
IFDEF SX48_52 ;SX48/52 RAM clear routine
mov w,#$0a ;reset all ram starting at $0A
mov fsr,w
:zero_ram clr ind ;clear using indirect addressing
incsz fsr ;repeat until done
jmp :zero_ram
_bank bank0 ;clear bank 0 registers
clr $10
clr $11
clr $12
clr $13
clr $14
clr $15
clr $16
clr $17
clr $18
clr $19
clr $1a
clr $1b
clr $1c
clr $1d
clr $1e
clr $1f
ELSE ;SX18/20/28 RAM clear routine
clr fsr ;reset all ram banks
:zero_ram sb fsr.4 ;are we on low half of bank?
setb fsr.3 ;If so, don't touch regs 0-7
clr ind ;clear using indirect addressing
incsz fsr ;repeat until done
jmp :zero_ram
ENDIF
;*********************************************************************************
; Initialize program/VP registers
;*********************************************************************************
;*********************************************************************************
; Setup and enable RTCC interrupt, WREG register, RTCC/WDT prescaler
;*********************************************************************************
RTCC_ON = %10000000 ;Enables RTCC at address $01 (RTW hi)
;*WREG at address $01 (RTW lo) by default
RTCC_ID = %01000000 ;Disables RTCC edge interrupt (RTE_IE hi)
;*RTCC edge interrupt (RTE_IE lo) enabled by default
RTCC_INC_EXT = %00100000 ;Sets RTCC increment on RTCC pin transition (RTS hi)
;*RTCC increment on internal instruction (RTS lo) is default
RTCC_FE = %00010000 ;Sets RTCC to increment on falling edge (RTE_ES hi)
;*RTCC to increment on rising edge (RTE_ES lo) is default
RTCC_PS_ON = %00000000 ;Assigns prescaler to RTCC (PSA lo)
RTCC_PS_OFF = %00001000 ;Assigns prescaler to RTCC (PSA lo)
PS_000 = %00000000 ;RTCC = 1:2, WDT = 1:1
PS_001 = %00000001 ;RTCC = 1:4, WDT = 1:2
PS_010 = %00000010 ;RTCC = 1:8, WDT = 1:4
PS_011 = %00000011 ;RTCC = 1:16, WDT = 1:8
PS_100 = %00000100 ;RTCC = 1:32, WDT = 1:16
PS_101 = %00000101 ;RTCC = 1:64, WDT = 1:32
PS_110 = %00000110 ;RTCC = 1:128, WDT = 1:64
PS_111 = %00000111 ;RTCC = 1:256, WDT = 1:128
mov w,#RTCC_PS_OFF ;setup option register
mov !option,w
jmp @main
;*****************************************************************************************
; MAIN PROGRAM CODE
;*****************************************************************************************
;*********************************************************************************
; Main
;*********************************************************************************
main
clrb CTS
jb rx_pin,$ ; until the user presses a key, loop indefinetely
clrb hook ; pick up the line
setb fsk_rx_en ; enable the FSK receiver
;*********************************************************************************
; Main Program Loop
;*********************************************************************************
main_loop
; Do nothing... ISR Does everything.
jmp main_loop
;*****************************************************************************************
END ;End of program code
;*****************************************************************************************
| file: /Techref/scenix/lib/io/dev/modem/simple_fsk_rcv_1_10.SRC, 32KB, , updated: 2002/4/11 12:05, local time: 2024/11/9 17:27,
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