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;Firmware for Digital RF Field Strength indicator ;with LED Display using Atmel AT90SA2313
;*********************************
; 7 Segment LED Display millivoltmeter
;*********************************
.include "2313def.inc"
;***** 16 bit binary-to-packed-BDC Subroutine Register Variables
.equ AtBCD0 =13 ;address of tBCD0
.equ AtBCD2 =15 ;address of tBCD1
.def tBCD0 =r13 ;BCD value digits 1 and 0
.def tBCD1 =r14 ;BCD value digits 3 and 2
.def tBCD2 =r15 ;BCD value digit 4
.def fbinL =r16 ;binary value Low byte
.def fbinH =r17 ;binary value High byte
.def cnt16a =r18 ;loop counter
.def tmp16a =r19 ;temporary value
;*****other register assignments************
.def segmentvalue = r0
.equ digit1 = $01 ;store of first digit's binary value
.def digit1val = r1 ;storage of first digit's 7 segment image
.equ digit2 = $02 ;storage of second digit's binary value
.def digit2val = r2 ;storage of second digit's 7 segment image
.equ digit3 =$03 ;storage of third ditit's binary value
.def digit3val = r3 ;storage of thrid digit's 7 segment image
.def offsetl = r4 ;offsete to zero reading, low byte
.def offseth =r5 ;offset to zero reading, high byte
.def flagreg = r6 ;bit 0 true enables measurement during interrupt
.def intcountl = r7 ;24 bit timer for power management
.def intcountm =r8 ;count low, middle, and high bytes
.def intcounth = r9
.def dimflag = r10 ;if not zero, then dim the display
.def rezeroedflag = r11 ;nonzero if rezero has occured
.def temp = r20 ;general purpose variabl
.def digitvalue = r21 ;value of current digit
.def digitpointer = r22 ;pointer to digit to be written
.def interruptcount = r23 ;keeps track of which task to execute next
.def slowdownmeasurements =r24 ;counter to cause less frequent measurements
;when I set this up at +5V and when operating from a 3V battery
.equ dimtime = $AE ;dim time 3 mintues
.equ sleeptime =$E8 ;shut down time at 4 minutes
.ORG $0000
rjmp start
.ORG $0006
rjmp timerservice
start:
ldi temp,RAMEND ;Init Stack Pointer
out SPL,temp
ldi temp,$00 ;clear measurement during interrupt enable flag
mov flagreg,temp
ldi temp,$FF ;segment drivers
out DDRD,temp
ldi temp,$FC ;digit drivers and power to the external circuit
out DDRB,temp
ldi temp,$3C ;digit drivers and power to the external circuit
out PORTB,temp
ldi temp, $00 ;set up comparitor
out ACSR, temp
ldi temp,$FF
mov dimflag,temp
;set interrupt counter to zero
clr intcountl
clr intcountm
clr intcounth
clr rezeroedflag
ldi temp, $03 ; use temp to initaize prescaler 03
out TCCR0, temp
ldi temp,$00 ; use temp to initialize counter
out TCNT0,temp
ldi temp, $02 ; use temp to initialize TIMSK
out TIMSK,temp
ldi temp,$FF ;clear measurement during interrupt enable flag
mov flagreg,temp
sei ;ENABLE THE TIMER INTERRUPTS
loop:
;check to see if its time to dim the display
ldi temp,dimtime ;skip dimming if intcountm is >< dimtime
eor temp,intcountm
brne dontdim
clr dimflag ;make register $FF if its time.
com dimflag
dontdim:
;check if its past time to sleep the machine
ldi temp,sleeptime ;skip sleeping if intcountm is >< sleep
eor temp,intcountm
brne dontsleep
;routine to sleep the machine
cli ;disble all interrupts
clr temp
out TCCR1b,temp ;stop timer 1
out TCCR0,temp ;stop timer 0
ldi temp,$18 ;make sure watch dog timer is disabled
out wdtcr,temp
ldi temp,$10
out wdtcr,temp
cbi ACSR,$07 ;turn off comparitor
;
clr temp ;make I/O pins inputs
out DDRB,temp
out DDRD,temp
ldi temp, $30
out MCUCR,temp ; set MCUCR bit 4 to set power down mode for sleep and
; set MCUCR bit 5 to enable sleep
sleep ; enter sleep. Reset to wake up.
dontsleep:
;Set up rezeroing of A-to-D after running some short time.
;rezeroiong only happens once and is done in the A-to-D routine inside
;the T0 interrupt.
tst rezeroedflag
brne dontrezero
ldi temp,$02
eor temp,intcountm
brne dontrezero
ldi temp,$5A
mov rezeroedflag,temp ;$5A is the secret word to cause rezeroing
dontrezero:
rjmp loop
;**** A P P L I C A T I O N N O T E A V R 2 0 4 ************************
;* Title: BCD Arithmetics
;* Version: 1.1
;* Last updated: 97.07.04
;* Target: AT90Sxxxx (All AVR Devices)
;*
;* Support E-mail: avr@atmel.com
;*
;* DESCRIPTION
;* This Application Note lists subroutines for the following Binary Coded
;* Decimal arithmetic applications:
;*
;* Binary 16 to BCD Conversion (special considerations for AT90Sxx0x)
;***** Code
bin2BCD16:
ldi cnt16a,16 ;Init loop counter
clr tBCD2 ;clear result (3 bytes)
clr tBCD1
clr tBCD0
clr ZH ;clear ZH (not needed for AT90Sxx0x)
bBCDx_1:lsl fbinL ;shift input value
rol fbinH ;through all bytes
rol tBCD0 ;
rol tBCD1
rol tBCD2
dec cnt16a ;decrement loop counter
brne bBCDx_2 ;if counter not zero
ret ; return
bBCDx_2:ldi r30,AtBCD2+1 ;Z points to result MSB + 1
bBCDx_3:
ld tmp16a,-Z ;get (Z) with pre-decrement
;----------------------------------------------------------------
;For AT90Sxx0x, substitute the above line with:
;
; dec ZL
; ld tmp16a,Z
;
;----------------------------------------------------------------
subi tmp16a,-$03 ;add 0x03
sbrc tmp16a,3 ;if bit 3 not clear
st Z,tmp16a ; store back
ld tmp16a,Z ;get (Z)
subi tmp16a,-$30 ;add 0x30
sbrc tmp16a,7 ;if bit 7 not clear
st Z,tmp16a ; store back
cpi ZL,AtBCD0 ;done all three?
brne bBCDx_3 ;loop again if not
rjmp bBCDx_1
putsegments: ; Enter with value (0..9) in digitvalue,
; and destingation digit in digitpointer
ldi ZH,high(2*ledlut) ; Load high part of byte address into ZH
ldi ZL,low(2*ledlut) ; Load low part of byte address into ZL
add ZL,digitvalue ; Add index (which is digitvalue) to LUT address
ldi temp,$00
adc ZH,temp
lpm ; Load byte from program memory into r0
mov ZL,digitpointer ;Point Z register to the desination memroy location
ldi ZH,$00
st Z,r0 ;move contets of r0 to location pointed to by digitpointer
ret
dimifnecessary:
;check if its past time to start dimming
tst dimflag
breq donedim
dimit: ;routine to dim the display
dimmingtime: ;leave the chars on some some
ldi fbinL,$00
ldi fbinH,$03
dimmingtimeloop:
dec fbinL
cpi fbinL,$00
brne dimmingtimeloop
dec fbinH
cpi fbinH,$00
brne dimmingtimeloop
;now that thime's up, blank display to dim.
cbi PORTB,2 ;blank all digits
cbi PORTB,3
cbi PORTB,4
donedim:
ret
;************************
timerservice: ;service timer interrupt
;round-robin multitasking, different task on each interrupt
;Display digit1
;display digit2
;display digit3
;acquire new ADC value and put in digit registers
push temp
push xl
push xh
lds temp,$5F ;push status register onto stack
push temp
push fbinL
push fbinH
ldi temp,$01 ;keep timer for dimming and shut down
add intcountl,temp
clr temp
adc intcountm,temp
adc intcounth,temp
inc interruptcount ;point to the next task
andi interruptcount,$03 ;only four tasks allowed
cbi PORTB,2 ;blank all digits
cbi PORTB,3 ;by making all cathode drivers inputs
cbi PORTB,4
;round-robin starts here
cpi interruptcount,$00
breq showdigit1
cpi interruptcount,$01
breq showdigit2
cpi interruptcount,$02
breq showdigit3
cpi interruptcount,$03
breq AtoDConversion
rjmp endoftimerservice ;go back and wait for another interrupt
showdigit1:
out PORTD,digit1val ;copy digit value to output port
sbi PORTB,4 ;enable this digit
rcall dimifnecessary
rjmp endoftimerservice
showdigit2:
out PORTD,digit2val ;copy digit value to output port
sbi PORTB,3 ;enable this digit
rcall dimifnecessary
rjmp endoftimerservice
showdigit3:
out PORTD,digit3val ;copy digit value to output port
sbi PORTB,2 ;enable this digit
rcall dimifnecessary
rjmp endoftimerservice
AtoDConversion:
;convert input voltage to a value, set flag for foreground routine to convert to BCD and store in digit memories
sbrs flagreg,$01 ;if flag not set, don't do conversions
jrelay: rjmp finishedconverison
inc slowdownmeasurements
cpi slowdownmeasurements,$08
brne jrelay ;don't do it, didn't wait long enough
clr slowdownmeasurements ;set counter to zero for next time
;set PORTB bit 0 to 0 to assure no current out of pins
cbi PORTB,0
;set DDRB, bit 0 an output. This discharges the capacitor on the I/O pin.
sbi DDRB,0
ldi fbinL,$00
ldi fbinH,$08
turnondelay:
dec fbinL
cpi fbinL,$00
brne turnondelay
;set DDRB bit 0 to input
cbi DDRB,$00
ldi xh,$00
ldi xl,$00
waitforramp:
sbiw xh:xl,1
in temp,acsr
sbis acsr,aco ;branch back to waiting if comparitor not tripped
rjmp waitforramp
;Zero ADC by measuring offset. Only happens once.
; after running about a
ldi temp,$5A
eor temp,rezeroedflag
brne dontrezeroagain
mov offsetl,xl
mov offseth,xh
ldi temp,$FF
mov rezeroedflag,temp
clr dimflag
dontrezeroagain:
sub xl,offsetl ;subtract offset to zero reference reading
sbc xh,offseth
brpl positivenumber
ldi xh,0 ;if we'r here, its negative, so set to zero;
ldi xl,0 ;negative field strength doesn't make any sense in the real world
positivenumber: ;now we have the number, we just need to convert it.
; Check for overflow
mov temp,xh
andi temp,$0F
subi temp,$03
brpl overflow
brne defintelynotoverflow
mov temp,xl
subi temp,$E7
brpl overflow
defintelynotoverflow:
mov fbinL,xl ;move counter contents to input for number conversion
mov fbinH,xh
rcall bin2BCD16 ;Convert to 2.5-byte packed BCD format
;result: tBCD2:tBCD1:tBCD0 = $054321
mov digitvalue,tBCD0 ; now send it to the LED display
andi digitvalue,$0F
ldi digitpointer,$01
rcall putsegments
mov digitvalue,tBCD0
lsr digitvalue
lsr digitvalue
lsr digitvalue
lsr digitvalue
ldi digitpointer,$02
rcall putsegments
mov digitvalue,tBCD1
andi digitvalue,$0F
ldi digitpointer,$03
rcall putsegments
rjmp finishedconverison
overflow:
;set display for overflow indication
ldi digitvalue,$0A
ldi digitpointer,$01
rcall putsegments
ldi digitvalue,$0A
ldi digitpointer,$02
rcall putsegments
ldi digitvalue,$0A
ldi digitpointer,$03
rcall putsegments
finishedconverison:
endoftimerservice:
pop fbinH
pop fbinL
pop temp
sts $5F,temp ;restore status register
pop xh
pop xl
pop temp
reti
ledlut: ;LED Look-Up Table, Segent codes for 0..9 on 7 segment display
.db $3F,$06,$5B,$4F,$66,$6D,$7d,$07,$7F,$6F,$09,$08
;Please see the liability disclaimer on the HOME page.
; Contents ©2002 Richard Cappels All Rights Reserved.;http://projects.cappels.org/