sine-wave
caskaz
Posts: 957
Hi,.
I try to make sine-wave.
But wave is DC 1.66V to check by oscillooscop.
Connected RC-cuicuit at P0. R=1kohm C=103
sin_wave.spin
I think to not get value of sine_table.
But I can't find out where is incorrect code.
Please teach me advice.
Post Edited (caskaz) : 3/9/2010 5:43:11 AM GMT
I try to make sine-wave.
But wave is DC 1.66V to check by oscillooscop.
Connected RC-cuicuit at P0. R=1kohm C=103
CON _clkmode = xtal1 + pll16x _xinfreq = 5_000_000 OBJ sin : " sine_wave" PUB sin.start(0,1)
sin_wave.spin
VAR
long dira_, ctra_, cnt_
PUB start(pin, freq) : cog
dira_ := |< pin
ctra_ := %00110 << 26 + pin 'DUTY single-end
cnt_ := clkfreq/(8192 * freq)
cog := cognew(@entry, @dira_)
DAT
entry org
mov t1,par
rdlong dira,t1 ' dira_
add t1,#4
rdlong ctra,t1 ' ctra_
add t1,#4
rdlong period, t1 ' cnt_
mov degree,#0
:loop test degree,sin_90 wc ' get sine quadrant 2|4 int c
test degree,sin_180 wz ' get sine quadrant 3|4 into nz
negc degree,degree ' if sine quadrant 2|4, negate table offset
or degree,sin_table ' insert sine table base address >> 1
shl degree,#1 ' shift left to get final word address
rdword t1,degree ' read sine word from table
negnz t1,t1 ' if quadrnt 3|4, negate word
shl t1,#15
add t1,level
mov frqa,t1
add degree,#1
mov time, cnt
waitcnt time,period
jmp #:loop
sin_table long $0000E000 >> 1
sin_180 long $00001000
sin_90 long $00000800
level long $7fffffff
degree res 1
t1 res 1
period res 1
time res 1
I think to not get value of sine_table.
But I can't find out where is incorrect code.
Please teach me advice.
Post Edited (caskaz) : 3/9/2010 5:43:11 AM GMT
Comments
I think it's these two lines, because degree can be negative, i.e. $ffff in the upper 16 bits. Using OR to add the base address of the sin table does not work as expected in this case. You'd have to use:
... shl degree, #1 if_c add degree, sin_table_end if_nc add degree, sin_table ... sin_table long $e000 sin_table_end long $f001So in the case of carry set, the negative value is used to index the sin_table down from its end.
Edit: you also have to use another loop variable instead of 'degree', because degree is modified inside the loop. Just copy this loop variable to degree at the :loop label.
HTH,
Juergen
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
He died at the console of hunger and thirst.
Next day he was buried. Face down, nine edge first.
Post Edited (pullmoll) : 3/8/2010 8:39:12 AM GMT
Thank you foy your advise.
It fine works.
DAT entry org mov t1,par rdlong dira,t1 ' dira_ add t1,#4 rdlong ctra,t1 ' ctra_ add t1,#4 rdlong period, t1 ' cnt_ mov time, cnt add time,period mov degree,#0 :loop test degree,sin_90 wc test degree,sin_180 wz mov t2,degree and t2,mask negc t2,t2 shl t2,#1 if_c add t2,sin_table_end if_nc add t2,sin_table rdword t1,t2 negnz t1,t1 shl t1,#15 add t1,level mov frqa,t1 add degree,#1 waitcnt time,period jmp #:loop sin_table long $0000E000 sin_table_end long $0000F001 sin_180 long $00001000 sin_90 long $00000800 level long $7fffffff mask long $000007ff degree res 1 t1 res 1 t2 res 1 period res 1 time res 1Post Edited (caskaz) : 3/9/2010 9:14:52 AM GMT