; ******************************************************************************
; SX Demo Enhanced 2.0
;
;
; Length: 666 bytes (total)
; Authors: Parallax Inc., Craig Webb
; Written: 97/03/10 to 98/6/08
;
; This program implements eight virtual peripherals on Parallax, Inc.'s
; SX DEMO board. The various virtual peripherals are as follows:
;
; 1) 16-bit timer/frequency outputs (2)
; 2) Pulse-Width Modulated outputs (2)
; 3) Analog-to-Digital Converter(s) (ADC) (2)
; 4) Universal Asynchronous Receiver Transmitter (UART)
; 5) Time clock (keeps count in msec)
; 6) Software execution path switcher
; 7) Push button detection & debounce (4)
; 8) I2C serial (EEPROM) interface
;
; All of these peripherals (except the I2C interface) take advantage
; of the SX's internal RTCC-driven interrupt so that they can operate
; in the background while the main program loop is executing.
;
; Improvements over SX Demo original version:
; - I2C protocol EEPROM store/retrieve subroutines added
; - push button detection, debounce, and action vectors added
; - button presses signaled through UART interface
; - time clock (counts in msec) added with path switcher
; - 3 new UART user-interface functions added to access EEPROM
; - faster, shorter timer/freqency output code
; - faster, shorter analog to digital converter code
; - bug removed from adc code (adc value=0FFh when input=5V)
; - faster, shorter UART transmit code
; - interrupt vector example added
; - byte received flag (rx_flag) moved to common register bank
;
;******************************************************************************
;
;****** Assembler directives
;
; uses: SX28AC, 2 pages of program memory, 8 banks of RAM, high speed osc.
; operating in turbo mode, with 8-level stack & extended option reg.
;
DEVICE pins28,pages2,banks8,oschs
DEVICE turbo,stackx,optionx
ID 'SXDemo20' ;program ID label
RESET reset_entry ;set reset/boot address
;
;******************************* Program Variables ***************************
;
; Port Assignment: Bit variables
;
scl EQU RA.0 ;I2C clock
sda EQU RA.1 ;I2C data I/O
rx_pin EQU ra.2 ;UART receive input
tx_pin EQU ra.3 ;UART transmit output
led_pin EQU rb.6 ;LED output
spkr_pin EQU rb.7 ;Speaker output
pwm0_pin EQU rc.0 ;Pulse width mod. PWM0 output
pwm1_pin EQU rc.2 ;Pulse width mod. PWM1 output
adc0_out_pin EQU rc.4 ;ADC0 input pin
adc0_in_pin EQU rc.5 ;ADC0 output/calibrate pin
adc1_out_pin EQU rc.6 ;ADC1 input pin
adc1_in_pin EQU rc.7 ;ADC1 output/calibrate pin
button0 EQU RB.0 ;Push button 0
button1 EQU RB.1 ;Push button 1
button2 EQU RB.2 ;Push button 2
button3 EQU RB.3 ;Push button 3
;
;
;****** Register definitions (bank 0)
;
org 8 ;start of program registers
main = $ ;main bank
;
temp ds 1 ;temporary storage
byte ds 1 ;temporary UART/I2C shift reg.
cmd ds 1
number_low ds 1 ;low byte of rec'd value
number_high ds 1 ;high byte of rec'd value
hex ds 1 ;value of rec'd hex number
string ds 1 ;indirect ptr to output string
flags DS 1 ;program flags register
;
got_hex EQU flags.0 ;=1 if hex value after command
seq_flag EQU flags.1 ;I2C: R/W mode (if sequential=1)
got_ack EQU flags.2 ; if we got ack signal
erasing EQU flags.3 ; high while erasing eeprom
rx_flag EQU flags.4 ;signals when a byte is received
;
org 30h ;bank1 variables
timers = $ ;timer bank
;
timer_low ds 1 ;timer value low byte
timer_high ds 1 ;timer value high byte
timer_accl ds 1 ;timer accumulator low byte
timer_acch ds 1 ;timer accumulator high byte
freq_low ds 1 ;frequency value low byte
freq_high ds 1 ;frequency value high byte
freq_accl ds 1 ;frequency accumulator low byte
freq_acch ds 1 ;frequency accumulator high byte
;
;
org 50h ;bank2 variables
analog = $ ;pwm and ADC bank
;
port_buff ds 1 ;buffer - used by all
pwm0 ds 1 ;pwm0 - value
pwm0_acc ds 1 ; - accumulator
pwm1 ds 1 ;pwm1 - value
pwm1_acc ds 1 ; - accumulator
adc0 ds 1 ;adc0 - value
adc0_count ds 1 ; - real-time count
adc0_acc ds 1 ; - accumulator
adc1 ds 1 ;adc1 - value
;adc1_count ds 1 ; - real-time count
adc1_acc ds 1 ; - accumulator
;
;
org 70h ;bank3 variables
serial = $ ;UART bank
;
tx_high ds 1 ;hi byte to transmit
tx_low ds 1 ;low byte to transmit
tx_count ds 1 ;number of bits sent
tx_divide ds 1 ;xmit timing (/16) counter
rx_count ds 1 ;number of bits received
rx_divide ds 1 ;receive timing counter
rx_byte ds 1 ;buffer for incoming byte
;
; The following three values determine the UART baud rate.
; The value of baud_bit and int_period affect the baud rate as follows:
; Baud rate = 50MHz/(2^baud_bit * int_period * RTCC_prescaler)
; Note: 1 =< baud_bit =< 7
; *int_period must <256 and longer than the length of the slowest
; possible interrupt sequence in instruction cycles.
; Changing the value of int_period will affect the
; rest of the virtual peripherals due to timing issues.
; The start delay value must be set equal to (2^baud_bit)*1.5 + 1
;
; *** 19200 baud
baud_bit = 4 ;for 19200 baud
start_delay = 16+8+1 ; " " "
int_period = 163 ; " " "
;
; *** 2400 baud (for slower baud rates, increase the RTCC prescaler)
;baud_bit = 7 ;for 2400 baud
;start_delay = 128+64+1 ; " " "
;int_period = 163 ; " " "
;
; *** 115.2k baud (for faster rates, reduce int_period - see above*)
;baud_bit = 1 ;for 115.2K baud
;start_delay = 2+1+1 ; " " "
;int_period = 217 ; " " "
;
org 90H ;bank4 variables
I2C EQU $ ;I2C bank
;
data DS 1 ;data byte from/for R/W
address DS 1 ;byte address
count DS 1 ;bit count for R/W
delay DS 1 ;timing delay for write cycle
byte_count DS 1 ;number of bytes in R/W
num_bytes DS 1 ;number of byte to view at once
save_addr DS 1 ;backup location for address
;
in_bit EQU byte.0 ;bit to receive on I2C
out_bit EQU byte.7 ;bit to transmit on I2C
;
control_r = 10100001b ;control byte: read E2PROM
control_w = 10100000b ;control byte: write E2PROM
portsetup_r = 00000110b ;Port A config: read bit
portsetup_w = 00000100b ;Port A config: write bit
eeprom_size = 128 ;storage space of EEPROM
;
t_all = 31 ;bit cycle delay (62=5 usec)
;
org 0B0H ;bank5 variables
clock EQU $ ;clock bank
buttons EQU $ ;push button bank
;
time_base_lo DS 1 ;time base delay (low byte)
time_base_hi DS 1 ;time base delay (high byte)
msec_lo DS 1 ;millisecond count (low)
msec_hi DS 1 ;millisecond count (high)
;
tick_lo = 80 ;instruction count for
tick_hi = 195 ; 50MHz xtal, turbo, prescaler=1
;
debounce0 DS 1 ;push button 0 debounce count
debounce1 DS 1 ;push button 1 debounce count
debounce2 DS 1 ;push button 2 debounce count
debounce3 DS 1 ;push button 3 debounce count
pbflags DS 1 ;push button status flags
pb0_pressed EQU pbflags.0 ;push button 0 action status
pb1_pressed EQU pbflags.1 ;push button 1 action status
pb2_pressed EQU pbflags.2 ;push button 2 action status
pb3_pressed EQU pbflags.3 ;push button 3 action status
pb0_down EQU pbflags.4 ;push button 0 down status
pb1_down EQU pbflags.5 ;push button 1 down status
pb2_down EQU pbflags.6 ;push button 2 down status
pb3_down EQU pbflags.7 ;push button 3 down status
;
hold_bit = 3 ;debounce period = 2^hold_bit msec
;
;*************************** INTERRUPT VECTOR ******************************
;
; Note: The interrupt code must always originate at 0h.
; A jump vector is not needed if there is no program data that needs
; to be accessed by the IREAD instruction, or if it can all fit into
; the lower half of page 0 with the interrupt routine.
;
ORG 0 ;interrupt always at 0h
; JMP interrupt ;interrupt vector
;
;***************************** PROGRAM DATA ********************************
;
; String data for user interface (must be in lower half of memory page 0)
;
; <this data has been strategically placed within the interrupt routine,
; after the path switch VP in order to save the interrupt jump vector byte
; and the three required instruction cycles.>
;
;**************************** INTERRUPT CODE *******************************
;
; Note: Care should be taken to see that any very timing sensitive routines
; (such as adcs, etc.) are placed before other peripherals or code
; which may have varying execution rates (like the UART, for example).
;
interrupt ;beginning of interrupt code
;
;****** Virtual Peripheral: TIMERS (including frequency output)
;
; This routine adds a programmable value to a 16-bit accumulator (a pair of
; two 8-bit registers) during each pass through the interrupt. It then
; copies the value from the high bit of the accumulator to the
; appropriate output port pin (LED, speaker, etc.)
;
; Input variable(s) : timer_low,timer_high,timer_accl,timer_acch
; freq_low,freq_high,freq_accl,freq_acch
; Output variable(s) : LED port pin, speaker port pin
; Variable(s) affected : timer_accl, timer_acch, freq_accl, freq_acch
; Flag(s) affected : none
; Size : 1 byte + 10 bytes (per timer)
; Timing (turbo) : 1 cycle + 10 cycles (per timer)
;
bank timers ;switch to timer reg. bank
:timer
; clc ;only needed if CARRYX=ON
add timer_accl,timer_low ;adjust timer's accumulator
addb timer_acch,c ; including carry bit
add timer_acch,timer_high ; (timer = 16 bits long)
movb led_pin,timer_acch.7 ;toggle LED (square wave)
:frequency
; clc ;only needed if CARRYX=ON
add freq_accl,freq_low ;adjust freq's accumulator
addb freq_acch,c ; including carry bit
add freq_acch,freq_high ; (freq = 16 bits long)
movb spkr_pin,freq_acch.7 ;toggle speaker(square wave)
;
;
;***** Virtual Peripheral: Pulse Width Modulators
;
; These routines create an 8-bit programmable duty cycle output at the
; respective pwm port output pins whose duty cycle is directly proportional
; to the value in the corresponding pwm register. This value is added to an
; accumulator on each interrupt pass interrupt. When the addition causes a
; carry overflow, the ouput is set to the high part of its duty cycle.
; These routines are timing critical and must be placed before any
; variable-execution-rate code (like the UART, for example).
;
; Input variable(s) : pwm0,pwm0_acc,pwm1,pwm1_acc
; Output variable(s) : pwm port pins
; Variable(s) affected : port_buff, pwm0_acc, pwm1_acc
; Flag(s) affected : none
; Size : 2 bytes + 4 bytes (per pwm)
; + 2 bytes shared with adc code (see below)
; Timing (turbo) : 2 cycles + 4 cycles (per pwm)
; + 2 cycles shared with adc code (see below)
;
bank analog ;switch to adc/pwm bank
clr port_buff ;clear pwm/adc port buffer
;
:pwm0 add pwm0_acc,pwm0 ;adjust pwm0 accumulator
snc ;did it trigger?
setb port_buff.0 ;yes, toggle pwm0 high
:pwm1 add pwm1_acc,pwm1 ;adjust pwm1 accumulator
snc ;did it trigger?
setb port_buff.2 ;yes, toggle pwm1 high
;
;*** If the ADC routines are removed, the following instruction must be
;*** enabled (uncommented) for the PWM routine to function properly:
;:update_RC mov rc,port_buff ;update cap. discharge pins
;
;
;***** Virtual Peripheral: Bitstream Analog to Digital Converters
;
; These routines allow an 8-bit value to be calculated which corresponds
; directly (within noise variation limits) with the voltage (0-5V) present
; at the respective adc port input pins. These routines are timing critical
; and must be placed before any variable-execution-rate code (like the UART,
; for example). The currently enabled routine (version A) has been optimized
; for size and speed, and RAM register usage, however a fixed execution rate,
; yet slightly larger/slower routine (version B) is provided in commented
; (disabled) form to simplify building other timing-critical virtual
; peripheral combinations (i.e. that require fixed rate preceeding code).
; Note: if version B is selected, version A must be disabled (commented)
;
; Input variable(s) : adc0,adc0_acc,adc0_count,adc1,adc1_acc,adc1_count
; Output variable(s) : pwm port pins
; Variable(s) affected : port_buff, pwm0_acc, pwm1_acc
; Flag(s) affected : none
; Size (version A) : 9 bytes + 7 bytes (per pwm)
; + 2 bytes shared with adc code (see below)
; Size (version B) : 6 bytes + 10 bytes (per pwm)
; + 2 bytes shared with pwm code (see below)
; Timing (turbo)
; version A : 2 cycles shared with pwm code (see below) +
; (a) [>99% of time] 11 cycles + 4 cycles (per adc)
; (b) [<1% of time] 9 cycles + 7 cycles (per adc)
; version B : 6 cycles + 10 cycles (per adc)
; + 2 cycles shared with pwm code (see below)
;
;*** If the PWM routines are removed, the following 2 instructions must
;*** be enabled (uncommented) for the ADC routine to function properly:
; bank analog ;switch to adc/pwm bank
; clr port_buff ;clear pwm/adc port buffer
:adcs mov w,>>rc ;get current status of adc's
not w ;complement inputs to outputs
and w,#%01010000 ;keep only adc0 & adc1
or port_buff,w ;store new value into buffer
:update_RC mov rc,port_buff ;update cap. discharge pins
;
; VERSION A - smaller, quicker but with variable execution rate
;
:adc0 sb port_buff.4 ;check if adc0 triggered?
INCSZ adc0_acc ;if so, increment accumulator
INC adc0_acc ; and prevent overflowing
DEC adc0_acc ; by skipping second 'INC'
:adc1 sb port_buff.6 ;check if adc1 triggered
INCSZ adc1_acc ;if so, increment accumulator
INC adc1_acc ; and prevent overflowing
DEC adc1_acc ; by skipping second 'INC'
INC adc0_count ;adjust adc0 timing count
JNZ :done_adcs ;if not done, jump ahead
:update_adc0 MOV adc0,adc0_acc ;samples ready, update adc0
:update_adc1 MOV adc1,adc1_acc ; update adc1
:clear_adc0 CLR adc0_acc ; reset adc0 accumulator
:clear_adc1 CLR adc1_acc ; reset adc1 accumulator
;
; <end of version A>
;
; VERSION B - fixed execution rate
;
;*** The "adc1_count" register definition in the analog bank definition
;*** section must be enabled (uncommented) for this routine to work properly
;
;:adc0 sb port_buff.4 ;check if adc0 triggered
; INCSZ adc0_acc ;if so, increment accumulator
; INC adc0_acc ; and prevent overflowing
; DEC adc0_acc ; by skipping second 'INC'
; mov w,adc0_acc ;load W from accumulator
; inc adc0_count ;adjust adc0 timing count
; snz ;are we done taking reading?
; mov adc0,w ;if so, update adc0
; snz ;
; clr adc0_acc ;if so, reset accumulator
;
;:adc1 sb port_buff.6 ;check if adc1 triggered
; INCSZ adc1_acc ;if so, increment accumulator
; INC adc1_acc ; and prevent overflowing
; DEC adc1_acc ; by skipping second 'INC'
; mov w,adc1_acc ;load W from accumulator
; inc adc1_count ;adjust adc1 timing count
; snz ;are we done taking reading?
; mov adc1,w ;if so, update adc1
; snz ;
; clr adc1_acc ;if so, reset accumulator
;
; <end of version B>
;
:done_adcs
;
;**** Virtual Peripheral: Universal Asynchronous Receiver Transmitter (UART)
;
; This routine sends and receives RS232C serial data, and is currently
; configured (though modifications can be made) for the popular
; "No parity-checking, 8 data bit, 1 stop bit" (N,8,1) data format.
; RECEIVING: The rx_flag is set high whenever a valid byte of data has been
; received and it the calling routine's responsibility to reset this flag
; once the incoming data has been collected.
; TRANSMITTING: The transmit routine requires the data to be inverted
; and loaded (tx_high+tx_low) register pair (with the inverted 8 data bits
; stored in tx_high and tx_low bit 7 set high to act as a start bit). Then
; the number of bits ready for transmission (10=1 start + 8 data + 1 stop)
; must be loaded into the tx_count register. As soon as this latter is done,
; the transmit routine immediately begins sending the data.
; This routine has a varying execution rate and therefore should always be
; placed after any timing-critical virtual peripherals such as timers,
; adcs, pwms, etc.
; Note: The transmit and receive routines are independent and either may be
; removed, if not needed, to reduce execution time and memory usage,
; as long as the initial "BANK serial" (common) instruction is kept.
;
; Input variable(s) : tx_low (only high bit used), tx_high, tx_count
; Output variable(s) : rx_flag, rx_byte
; Variable(s) affected : tx_divide, rx_divide, rx_count
; Flag(s) affected : rx_flag
; Size : Transmit - 15 bytes + 1 byte shared with receive code
; Receive - 20 bytes + 1 byte shared with transmit code
; Timing (turbo) :
; Transmit - (a) [not sending] 9 cycles
; (b) [sending] 19 cycles
; + 1 cycle shared with RX code ("bank" instr.)
; Receive - (a) [not receiving] 9 cycles
; (b) [start receiving] 16 cycles
; (c) [receiving, awaiting bit] 13 cycles
; (d) [receiving, bit ready] 17 cycles
;
;
bank serial ;switch to serial register bank
:transmit clrb tx_divide.baud_bit ;clear xmit timing count flag
inc tx_divide ;only execute the transmit routine
STZ ;set zero flag for test
SNB tx_divide.baud_bit ; every 2^baud_bit interrupt
test tx_count ;are we sending?
JZ :receive ;if not, go to :receive
clc ;yes, ready stop bit
rr tx_high ; and shift to next bit
rr tx_low ;
dec tx_count ;decrement bit counter
movb tx_pin,/tx_low.6 ;output next bit
;
:receive movb c,rx_pin ;get current rx bit
test rx_count ;currently receiving byte?
jnz :rxbit ;if so, jump ahead
mov w,#9 ;in case start, ready 9 bits
sc ;skip ahead if not start bit
mov rx_count,w ;it is, so renew bit count
mov rx_divide,#start_delay ;ready 1.5 bit periods
:rxbit djnz rx_divide,:rxdone ;middle of next bit?
setb rx_divide.baud_bit ;yes, ready 1 bit period
dec rx_count ;last bit?
sz ;if not
rr rx_byte ; then save bit
snz ;if so
setb rx_flag ; then set flag
:rxdone
;
;****** Virtual Peripheral: Time Clock
;
; This routine maintains a real-time clock count (in msec) and allows processing
; of routines which only need to be run once every millisecond.
;
; Input variable(s) : time_base_lo,time_base_hi,msec_lo,msec_hi
; Output variable(s) : msec_lo,msec_hi
; Variable(s) affected : time_base_lo,time_base_hi,msec_lo,msec_hi
; Flag(s) affected :
; Size : 18 bytes
; Timing (turbo) : [99.9% of time] 15 cycles
; [0.1% of time] 18 cycles
;
BANK clock ;select clock register bank
MOV W,#int_period ;load period between interrupts
ADD time_base_lo,W ;add it to time base
SNC ;skip ahead if no underflow
INC time_base_hi ;yes overflow, adjust high byte
MOV W,#tick_hi ;check for 1 msec click
MOV W,time_base_hi-W ;Is high byte above or equal?
MOV W,#tick_lo ;load instr. count low byte
SNZ ;If hi byte equal, skip ahead
MOV W,time_base_lo-W ;check low byte vs. time base
SC ;skip ahead if low
JMP done_int ;If not, end interrupt
:got_tick CLR time_base_hi ;Yes, adjust time_base reg.'s
SUB time_base_lo,#tick_lo ; leaving time remainder
INCSZ msec_lo ;And adjust msec count
DEC msec_hi ; making sure to adjust high
INC msec_hi ; byte as necessary
:done_clock
;this next line is needed only to allow flashing the pb0 & pb1 LEDs
MOV !RB,#00001111b ;set up pb's as inputs
;****** Virtual Peripheral: Path Switch
;
; This routine allows alternating execution of multiple modules which don't
; need to be run during every interrupt pass in order to reduce the overall
; execution time of the interrupt on any given pass (i.e. it helps the code
; run faster).
; This version runs with the software clock virtual peripheral msec_lo variable
; allowing altenation between the switch positions once each millisecond.
;
; Input variable(s) : msec_lo
; Output variable(s) :
; Variable(s) affected :
; Flag(s) affected :
; Size : 3 bytes + 1 bytes per jump location
; Timing (turbo) : 8 cycles
;
:path_switch MOV W,msec_lo ;load switch selector byte
AND W,#00000011b ;keep low 2 bits - 4 position
JMP PC+W ;jump to switch position pointer
:pos0 JMP pb0 ;pushbutton 0 checking routine
:pos1 JMP pb1 ;pushbutton 1 checking routine
:pos2 JMP pb2 ;pushbutton 2 checking routine
:pos3 JMP pb3 ;pushbutton 3 checking routine
;
;
;***************************** PROGRAM DATA ********************************
;
; String data for user interface (must be in lower half of memory page 0)
;
_hello dw 13,10,13,10,'SX Virtual Peripheral Demo 2.0'
_cr DW 13,10,0
_prompt dw 13,10,'>',0
_error dw 'Error!',13,10,0
_hex dw '0123456789ABCDEF'
_space DW ' ',0
_sample DW 13,10,'Sample=',0
_view DW 13,10,'Bytes stored:',0
_pressed DW 13,10,'Pressed: button ',0
;
;
;****** Virtual Peripheral: Push Buttons*
;
; This routine monitors any number of pushbuttons, debounces them properly
; as needed, and flags the main program code as valid presses are received.
; *Note: this routine requires the Time Clock virtual peripheral or similar
; pre-processing timer routine.
;
; Input variable(s) : pb0_down,pb1_down,debounce0,debounce1
; pb2_down,pb3_down,debounce2,debounce3
; Output variable(s) : pb0_pressed, pb1_pressed, pb2_pressed, pb3_pressed
; Variable(s) affected : debounce0, debounce1, debounce2, debounce3
; Flag(s) affected : pb0_down,pb1_down,pb0_pressed,pb1_pressed
; pb2_down,pb3_down,pb2_pressed,pb3_pressed
; Size : 12 bytes per pushbutton + actions (see below**)
; + 1 byte if path switch not used
; Timing (turbo) : 7,10, or 12 cycles/pushbutton (unless path switch used)
; + actions (see below**)
;
pb0
; BANK buttons ;select bank (if not done elsewhere)
JB button0,:pb0_up ;button0 pressed?
JB pb0_down,:done_pb0 ;yes, but is it new press?
INC debounce0 ; and adjust debounce count
JNB debounce0.hold_bit,:done_pb0 ;wait till long enough
SETB pb0_down ;yes, flag that button is down
;**If the button activity is short (a few bytes), it can fit here, though be
; careful that longest possible interrupt doesn't exceed int_period # of cycles.
;
; <short code segment can go here>
;
;**Otherwise, use this flag to process button press in main code (and don't
; forget to reset the flag once the button activity is complete).
SETB pb0_pressed ; and set pb0 action flag
SKIP ;skip next instruction
:pb0_up CLRB pb0_down ;button up, clear flag
CLR debounce0 ; and clear debounce count
:done_pb0
;
JMP done_int ;this needed only if path switch used
pb1
; BANK buttons ;do bank select (if not done elsewhere)
JB button1,:pb1_up ;button1 pressed?
JB pb1_down,:done_pb1 ;yes, but is it new press?
INC debounce1 ; and adjust debounce count
JNB debounce1.hold_bit,:done_pb1 ;wait till long enough
SETB pb1_down ;yes, flag that button is down
;**If the button activity is short (a few bytes), it can fit here, though be
; careful that longest possible interrupt doesn't exceed int_period # of cycles.
;
; <short code segment can go here>
;
;**Otherwise, use this flag to process button press in main code (and don't
; forget to reset the flag once the button activity is complete).
SETB pb1_pressed ; and set pb1 action flag
SKIP ;skip next instruction
:pb1_up CLRB pb1_down ;button up, clear flag
CLR debounce1 ; and clear debounce count
:done_pb1
;
JMP done_int ;this needed only if path switch used
pb2
; BANK buttons ;do bank select (if not done elsewhere)
JB button2,:pb2_up ;button2 pressed?
JB pb2_down,:done_pb2 ;yes, but is it new press?
INC debounce2 ; and adjust debounce count
JNB debounce2.hold_bit,:done_pb2 ;wait till long enough
SETB pb2_down ;yes, flag that button is down
;**If the button activity is short (a few bytes), it can fit here, though be
; careful that longest possible interrupt doesn't exceed int_period # of cycles.
;
;**Otherwise, use this flag to process button press in main code (and don't
; orget to reset the flag once the button activity is complete).
SETB pb2_pressed ; and set pb2 action flag
SKIP ;skip next instruction
:pb2_up CLRB pb2_down ;button up, clear flag
CLR debounce2 ; and clear debounce count
:done_pb2
;
JMP done_int ;this needed only if path switch used
pb3
; BANK buttons ;do bank select (if not done elsewhere)
JB button3,:pb3_up ;button3 pressed?
JB pb3_down,:done_pb3 ;yes, but is it new press?
INC debounce3 ; and adjust debounce count
JNB debounce3.hold_bit,:done_pb3 ;wait till long enough
SETB pb3_down ;yes, flag that button is down
;**If the button activity is short (a few bytes), it can fit here, though be
; careful that longest possible interrupt doesn't exceed int_period # of cycles.
;
;**Otherwise, use this flag to process button press in main code (and don't
; forget to reset the flag once the button activity is complete).
SETB pb3_pressed ; and set pb3 action flag
SKIP ;skip next instruction
:pb3_up CLRB pb3_down ;button up, clear flag
CLR debounce3 ; and clear debounce count
:done_pb3
; ;***these next 7 lines are needed only to allow flashing the pb0 & pb1 LEDs
MOV !RB,#00001100b ;return pb's to LED outputs
SETB button0 ;flash pb0 LED
SB msec_hi.1 ; roughly once/sec
CLRB button0 ;
CLRB button1 ; alternating with pb1 LED
SB msec_hi.1 ;
SETB button1 ;
done_int ;interrupt routines complete
;
; Maximum interrupt length = 21 (timers:2) + 12 (PWMs:2) + 23 (ADCs:2) + 37 (UART)
; + 18 (clock) + 8 (switch) + (12) (PBs) + 10 (leds)
; + 4 (next two instr.) + 6 (RTCC interrupt processing)
; = 163 cycles (must be =< int_period)
mov w,#-int_period ;interrupt every 'int_period' clocks
retiw ;exit interrupt
;
;****** End of interrupt sequence
;
;************************** RESET ENTRY POINT *****************************
;
reset_entry PAGE start ;Set page bits and then
JMP start ; jump to start of code
;***************************** SUBROUTINES *********************************
;
; Note: These subroutines must appear in the lower 256 bytes of any given
; memory page. Here, page 1 (=200h) is used. Remember to set page bits
; when accessing them from other than page 2 of program memory.
ORG 200h
;
;
; Subroutine - Get byte via serial port
;
get_byte
;the following code watches pb0-pb3 for presses and acts on them
BANK buttons ;select clock/pb bank
MOV W,pbflags ;load pushbutton flags
BANK serial ;re-select serial bank
AND W,#00001111b ;keep only 'pressed' flags
JZ :no_press ;jump ahead if not pressed
MOV temp,W ;store flags temporarily
MOV W,#_pressed ;point to "pressed" string
CALL send_string ;send it out via UART
CLR string ;clear 2nd temp storage reg.
:which_pb INC string ;increment 2nd temp value
RR temp ;check which button
SC ;skip ahead if not this one
JMP :which_pb ;keep looping
MOV W,--string ;get 2nd temp value (less 1)
MOV temp,W ;save it in temp
MOV W,#'0' ;get the '0' character
ADD W,temp ;and adjust it as needed
CALL send_byte ;and send it out via UART
BANK buttons ;select button bank
MOV W,#11110000b ;get clear mask for pbflags
AND pbflags,W ;clear all "pressed" flags
MOV W,temp ;get which button pressed
JMP PC+W ;Go do PB routines
:pb0 JMP pb0_action ;do pb0 action
:pb1 JMP pb1_action ;do pb1 action
:pb2 JMP pb2_action ;do pb2 action
:pb3 JMP pb3_action ;do pb3 action
:no_press jnb rx_flag,get_byte ;wait till byte is received
clrb rx_flag ;reset the receive flag
mov byte,rx_byte ;store byte (copy using W)
; & fall through to echo char back
;
; Subroutine - Send byte via serial port
;
send_byte bank serial
:wait test tx_count ;wait for not busy
jnz :wait ;
not w ;ready bits (inverse logic)
mov tx_high,w ; store data byte
setb tx_low.7 ; set up start bit
mov tx_count,#10 ;1 start + 8 data + 1 stop bit
RETP ;leave and fix page bits
;
; Subroutine - Send hex byte (2 digits)
;
send_hex mov w,#_cr ;get <cr> with <lf>
call send_string ; and send it
:num_only mov w,<>number_low ;get first digit
call :digit ; and send it
mov w,number_low ;load 2nd digit
:digit and w,#$F ;read hex chr
mov temp,w ; and store it temporarily
mov w,#_hex ;load hex table address
; clc ;only needed if CARRYX used
add w,temp ;calculate hex table offset
mov m,#0 ; and go get the appropriate
iread ; character with indirect
mov m,#$F ; addressing using MODE reg.
jmp send_byte ;go send hex character
;
;
; Subroutine - Send string pointed to by address in W register
;
send_string mov string,w ;store string address
:loop mov w,string ;read next string character
mov m,#0 ; with indirect addressing
iread ; using the mode register
mov m,#$F ;reset the mode register
test w ;are we at the last char?
snz ;if not=0, skip ahead
RETP ;yes, leave & fix page bits
call send_byte ;not 0, so send character
inc string ;point to next character
jmp :loop ;loop until done
;
;
; Subroutine - Make byte uppercase
;
uppercase csae byte,#'a' ;if byte is lowercase, then skip ahead
ret
sub byte,#'a'-'A' ;change byte to uppercase
RETP ;leave and fix page bits
;
; Subroutine - Convert hex number from ascii
;
get_hex clr number_low ;reset number
clr number_high
CLRB got_hex ;reset hex value flag
:loop call get_byte ;get digit
cje byte,#' ',:loop ;ignore spaces
mov w,<>byte ;get nibble-swapped byte
mov hex,w ; into hex register
cjb byte,#'0',:done ;if below '0', done
cjbe byte,#'9',:got ;if '0'-'9', got hex digit
call uppercase ;make byte uppercase
cjb byte,#'A',:done ;if below 'A', done
cja byte,#'F',:done ;if above 'F', done
add hex,#$90 ;'A'-'F', adjust hex digit
:got mov temp,#4 ;shift digit into number
:shift rl hex ; by rotating
rl number_low ; all three registers
rl number_high ; left 4 times
djnz temp,:shift ;
SETB got_hex ;flag that we got a value
jmp :loop ;go get next digit
:cr call get_byte ;get a byte via serial port
:done cjne byte,#13,:cr ;loop until it's a <cr>
RETP ;leave and fix page bits
;
;
;******************************** I2C Subroutines *****************************
;
; These routines write/read data to/from the 24LCxx EEPROM at a rate of approx.
; 200kHz. For faster* reads (up to 400 kHz max), read, write, start amd stop
; bit cycles and time between each bus access must be individually tailored
; using the CALL Bus_delay:custom entry point with appropriate values in the W
; register - in turbo mode: delay[usec] = 1/xtal[MHz] * (6 + 4 * (W-1)).
; Acknowledge polling is used to reduce delays between successive operations
; where the first of the two is a write operation. In this case, the speed
; is limited by the EEPROM's storage time.
;
;
;****** Subroutine(s) : Write to I2C EEPROM
; These routines write a byte to the 24LCxxB EEPROM. Before calling this
; subroutine, the address and data registers should be loaded accordingly. The
; sequential mode flag should be clear for normal byte writing operation.
; To write in sequential/page mode, please see application note.
;
; Input variable(s) : data, address, seq_flag
; Output variable(s) : none
; Variable(s) affected : byte, temp, count, delay
; Flag(s) affected : none
; Timing (turbo) : approx. 200 Kbps write rate
; : approx. 10 msec between successive writes
;
I2C_write CALL Set_address ;write address to slave
:page_mode MOV W,data ;get byte to be sent
CALL Write_byte ;Send data byte
JB seq_flag,:done ;is this a page write?
CALL Send_stop ;no, signal stop condition
:done RETP ;leave and fix page bits
;
Set_address CALL Send_start ;send start bit
MOV W,#control_w ;get write control byte
CALL Write_byte ;Write it & use ack polling
JNB got_ack,Set_address ; until EEPROM ready
MOV W,address ;get EEPROM address pointer
CALL Write_byte ; and send it
RETP ;leave and fix page bits
;
Write_byte MOV byte,W ;store byte to send
MOV count,#8 ;set up to write 8 bits
:next_bit CALL Write_bit ;write next bit
RL byte ;shift over to next bit
DJNZ count,:next_bit ;whole byte written yet?
CALL Read_bit ;yes, get acknowledge bit
SETB got_ack ;assume we got it
SNB in_bit ;did we get ack (low=yes)?
CLRB got_ack ;if not, flag it
;
; to use the LED as a 'no_ack' signal, the ':toggle_led' line in the interrupt
; section must be commented out, and the next 3 instructions uncommented.
; CLRB led_pin ;default: LED off
; SNB in_bit ;did we get ack (low=yes)?
; SETB led_pin ; if not, flag it with LED
;
RETP ;leave and fix page bits
;
Write_bit MOVB sda,out_bit ;put tx bit on data line
MOV !ra,#portsetup_w ;set Port A up to write
JMP :delay1 ;100ns data setup delay
:delay1 JMP :delay2 ; (note: 250ns at low power)
:delay2 SETB scl ;flip I2C clock to high
; MOV W,#t_high ;get write cycle timing*
CALL Bus_delay ;do delay while bus settles
CLRB scl ;return I2C clock low
MOV !ra,#portsetup_r ;set sda->input in case ack
; MOV W,#t_low ;get clock=low cycle timing*
CALL Bus_delay ;allow for clock=low cycle
RETP ;leave and fix page bits
;
Send_start SETB sda ;pull data line high
MOV !ra,#portsetup_w ;setup I2C to write bit
JMP :delay1 ;100ns data setup delay
:delay1 JMP :delay2 ; (note: 250ns at low power)
:delay2 SETB scl ;pull I2C clock high
; MOV W,#t_su_sta ;get setup cycle timing*
CALL Bus_delay ;allow start setup time
:new CLRB sda ;data line goes high->low
; MOV W,#t_hd_sta ;get start hold cycle timing*
CALL Bus_delay ;allow start hold time
CLRB scl ;pull I2C clock low
; MOV W,#t_buf ;get bus=free cycle timing*
CALL Bus_delay ;pause before next function
RETP ;leave and fix page bits
;
Send_stop CLRB sda ;pull data line low
MOV !ra,#portsetup_w ;setup I2C to write bit
JMP :delay1 ;100ns data setup delay
:delay1 JMP :delay2 ; (note: 250ns at low power)
:delay2 SETB scl ;pull I2C clock high
; MOV W,#t_su_sto ;get setup cycle timing*
CALL Bus_delay ;allow stop setup time
SETB sda ;data line goes low->high
; MOV W,#t_low ;get stop cycle timing*
CALL Bus_delay ;allow start/stop hold time
RETP ;leave and fix page bits
;
Bus_delay MOV W,#t_all ;get timing for delay loop
:custom MOV temp,W ;save it
:loop DJNZ temp,:loop ;do delay
RETP ;leave and fix page bits
;
;****** Subroutine(s) : Read from I2C EEPROM
; These routines read a byte from a 24LCXXB E2PROM either from a new address
; (random access mode), from the current address in the EEPROM's internal
; address pointer (CALL Read_byte:current), or as a sequential read. In either
; the random access or current address mode, seq_flag should be clear. Please
; refer to the application note on how to access the sequential read mode.
;
; Input variable(s) : address, seq_flag
; Output variable(s) : data
; Variable(s) affected : byte, temp, count, delay
; Flag(s) affected : none
; Timing (turbo) : reads at approx. 200Kbps
;
I2C_read CALL Set_address ;write address to slave
:current CALL Send_start ;signal start of read
MOV W,#control_r ; get read control byte
CALL Write_byte ; and send it
:sequential MOV count,#8 ;set up for 8 bits
CLR byte ;zero result holder
:next_bit RL byte ;shift result for next bit
CALL Read_bit ;get next bit
DJNZ count,:next_bit ;got whole byte yet?
MOV data,byte ;yes, store what was read
SB seq_flag ;is this a sequential read?
:non_seq JMP Send_stop ; no, signal stop & exit
CLRB out_bit ; yes, setup acknowledge bit
CALL Write_bit ; and send it
RETP ;leave and fix page bits
;
Read_bit CLRB in_bit ;assume input bit low
MOV !ra,#portsetup_r ;set Port A up to read
SETB scl ;flip I2C clock to high
; MOV W,#t_high ;get read cycle timing*
CALL Bus_delay ;Go do delay
SNB sda ;is data line high?
SETB in_bit ;yes, switch input bit high
CLRB scl ;return I2C clock low
; MOV W,#t_buf ;get bus=free cycle timing*
CALL Bus_delay ;Go do delay
RETP ;leave and fix page bits
;
;
Take_sample BANK analog ;switch to analog bank
MOV W,ADC1 ;get ADC1 value
BANK I2C ;switch to EEPROM bank
SNB got_hex ;did user enter a value?
MOV W,number_low ;yes, load it instead
MOV data,W ;save ADC1 value
CALL I2C_Write ;store it in EEPROM
INC address ;move to next address
INC byte_count ;adjust # bytes stored
MOV W,eeprom_size ;get memory size
MOV W,address-W ;are we past end?
SNZ ;if not, skip ahead
CLR address ;if so, reset it
:done RETP ;leave and fix page bits
;
Erase_Mem CLR address ;restore address pointer
SETB erasing ;flag erase operation
MOV num_bytes,#eeprom_size ;wipe whole mem
:wipeloop CLR data ;byte to wipe with=0
; MOV data,address ;byte to wipe with=addr
CALL I2C_write ;wipe EEPROM byte
INC address ;move to next address
DJNZ num_bytes,:wipeloop ;Erased enough yet?
CLR byte_count ;done, reset stored count
CLR save_addr ;reset backup address
MOV W,#eeprom_size ;load mem size into W
CALL View_mem:all ; and view cleared memory
CLRB erasing ;flag operation done
RETP ;leave and fix page bits
;
View_Mem MOV W,byte_count ;get # bytes stored
:all MOV num_bytes,W ;store it into view count
MOV W,#_view ;get view message
CALL send_string ;dump it
BANK I2C ;switch to EEPROM bank
MOV number_low,byte_count ;get byte storage count
CALL send_hex:num_only ;dump it
BANK I2C ;switch to I2C bank
MOV W,#0 ;Address = start of EEPROM
JMP :address ;Go store address
:single MOV num_bytes,#1 ;only a single byte
MOV W,number_low ;get the address pointer
:address MOV address,W ;store requested address
MOV W,#_cr ;get carriage return
:dump CALL send_string ;send it
BANK I2C ;Switch to I2C bank
SB erasing ;viewing after erase cycle
SNB got_hex ; or special hex value?
JMP :viewloop ;yes, go dump it
TEST save_addr ;no, is EEPROM empty?
SNZ ;if not, skip ahead
JMP :done ;yes, so leave
:viewloop CALL I2C_read ;fetch byte from EEPROM
MOV number_low,data ;setup to send it
CALL send_hex:num_only ;transmit it (RS232)
BANK I2C ;switch to I2C bank
DEC num_bytes ;decrement byte count
SNZ ;skip ahead if not done
JMP :done ;all bytes dumped, exit
INC address ;move to next address
MOV W,#00001111b ;keep low nibble
AND W,address ; of address pointer
MOV W,#_space ;default=send a space
SNZ ;have we done 16 bytes?
MOV W,#_cr ;yes, point to a <cr>
JMP :dump ;go dump it and continue
:done MOV address,save_addr ;restore address pointer
RETP ;leave and fix page bits
;
;************************** End of I2C Subroutines ****************************
;
;********
;* Main *
;********
;
start mov ra,#%1011 ;initialize port RA
mov !ra,#%0100 ;Set RA in/out directions
mov rb,#%10000000 ;initialize port RB
mov !rb,#%00001111 ;Set RB in/out directions
clr rc ;initialize port RC
mov !rc,#%10101010 ;Set RC in/out directions
mov m,#$D ;set input levels
mov !rc,#0 ; to cmos on port C
mov m,#$F ;reset mode register
CLR FSR ;reset all ram starting at 08h
: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
IJNZ FSR,:zero_ram ;repeat until done
bank timers ;set defaults
setb timer_low.0 ;LED off
setb freq_low.0 ;speaker off
mov !option,#%10011111 ;enable rtcc interrupt
;
; Terminal - main loop
;
terminal mov w,#_hello ;send hello string
call send_string
:loop mov w,#_prompt ;send prompt string
call send_string
call get_byte ;get command via UART
call uppercase ; make it uppercase
mov cmd,byte ; and store it
call get_hex ; get hex number (if present)
:check_cmds ;note: below, xx=hex value
cje cmd,#'T',:timer ;T xxxx
cje cmd,#'F',:freq ;F xxxx
cje cmd,#'A',:pwm0 ;A xx
cje cmd,#'B',:pwm1 ;B xx
cje cmd,#'C',:adc0 ;C
cje cmd,#'D',:adc1 ;D
; Command: S [xx] - Store sample (if xx is left out, ADC1 is sampled)
; - if xx is left out, adc1 value is stored
;
cje cmd,#'S',:sample ;S [xx] =store sample
;
; Command: V [xx] - View stored byte(s)
; - if xx is left out, all stored byted are shown
; - if xx=ff then whole eeprom is dumped
;
cje cmd,#'V',:view ;V [xx] =View EEPROM contents
;
; Command: E - Erase EEPROM contents and reset storage pointer
;
cje cmd,#'E',:erase ;E = Erase whole EEPROM
mov w,#_error ;bad command
call send_string ;send error string
jmp :loop ;try again
:timer bank timers ;timer write
mov timer_low,number_low ;store new timer value
mov timer_high,number_high ; (16 bits)
jmp :loop
:freq bank timers ;freq write
mov freq_low,number_low ;store new frequency value
mov freq_high,number_high ; (16 bits)
jmp :loop
:pwm0 bank analog ;pwm0 write
mov pwm0,number_low ;store new pwm0 value
jmp :loop
:pwm1 bank analog ;pwm1 write
mov pwm1,number_low ;store new pwm0 value
jmp :loop
:adc0 bank analog ;adc0 read
mov number_low,adc0 ;get current adc0 value
call send_hex ;transmit it (via UART)
jmp :loop
:adc1 bank analog ;adc1 read
mov number_low,adc1 ;get current adc1 value
call send_hex ; transmit it (via UART)
jmp :loop
:sample BANK I2C ;Switch to I2C bank
CALL Take_sample ;Go take a sample
MOV W,#_sample ;get sample message
CALL send_string ;dump it
BANK I2C ;switch to EEPROM bank
MOV number_low,data ;byte sent
CALL send_hex:num_only ;dump it
JMP :loop ;back to main loop
;
:view BANK I2C ;switch to I2C bank
MOV save_addr,address ;backup address pointer
SNB got_hex ;Was this "V xx" command?
JMP :v_special ;if so, jump
CALL View_mem ;no, view all stored data
JMP :loop ;back to main loop
:v_special MOV W,++number_low ;View whole mem=> "V ff"
JZ :v_whole ;Was this requested?
CALL View_mem:single ;yes, go dump it
JMP :loop ;back to main loop
:v_whole MOV W,#eeprom_size ;Get eeprom mem size
CALL View_mem:all ;Go dump the whole thing
JMP :loop ;back to main loop
;
:erase BANK I2C ;switch to I2C bank
CALL Erase_mem ;no, wipe whole EEPROM
JMP :loop ;back to main loop
;***************
pb0_action
BANK timers ;select timers bank
INC timer_low ;increase LED flash rate
INC freq_low ;increase frequency
BANK clock ;re-select clock bank
JMP terminal:loop
;
pb1_action
BANK timers ;select timers bank
DEC timer_low ;reduce LED flash rate
DEC freq_low ;reduce frequency
BANK clock ;re-select clock bank
JMP terminal:loop
;
pb2_action
;
; <button 2 action goes here>
;
JMP terminal:loop
;
pb3_action
;
; <button 3 action goes here>
;
JMP terminal:loop
;
;***************
END ;End of program code
| file: /Techref/scenix/8vp.src, 53KB, , updated: 2003/6/9 21:07, local time: 2024/11/12 11:50,
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