Problem 1. I have the tempo click getting added into the audio out, I think this is happening in the ;now produce output. part of the code.
Problem 2. The tapped tempo is inverse to the output, ie slow tempo=fast tremolo.
Any pointers please on where to look to fix these 2 problems ?
Code: Select all
;tap tempo tremolo
;slacker's tap tempo code + Demo rom tremolo code
;mono input (ADCL) mono output (DACL)
;a 0 - 0.99 square wave at the tap tempo rate is send to DACR. This can be used to flash a LED using a suitable driver.
;Pot 0 is used as a tap tempo switch input. This should be a momentary switch, transition can be high to low or low to high.
;see guitar amp application note for examples of switch hookup.
;pot 2 = feedback
;pot 1 = delay level
;set up registers and equates
equ db reg0 ;debounce
equ mom reg1 ;momentary output of switch +1 high, -1 Low
equ latch reg2 ;latched output of switch +1 high, -1 low
equ ramp reg3 ;current value of rmpo, scaled to 0 to 1
equ taptempo reg4 ;taptempo value, 0 to 1
equ led reg5 ;taptempo LED
equ mono reg6
equ trem reg7
equ count 0.01 ;debounce counter
equ delaytime 330 ;initial delay time in milli seconds
mem delay 32767
skp run,START
wldr rmp0,0.064,4096 ;set up rmp0
wldr rmp1,0.064,4096 ;set up rmp1
sof 0,0.99
wrax latch,1 ;set latch = 1 high
wrax led,0 ;set led = 1 high
sof 0,delaytime/1000 ;set initial delay time
wrax ramp,0
START:
;Switch Debouncing and pot filtering work around
ldax pot0 ;read pot0
sof 1,-0.5 ;level shift to -0.5 to 0.5
skp neg,DOWN ;if negative jump to DOWN
ldax db ;else high, read db
sof 1,count ;add count
wrax db,0 ;write new value to db
skp zro,ENDDB ;jump to ENDDB
DOWN:
ldax db ;read db
sof 1,-count ;deduct count
wrax db,0 ;write new value to db
ENDDB:
;latching switch, falling edge triggered flipflop
;Output of debounce routine of < -0.9 is low, > 0.9 is high, values in between
;are ignored and the switch does nothing, Schmitt trigger action.
ldax db ;read db
absa ;get absolute value
sof 1,-0.9 ;deduct 0.9 so only values < -0.9 or > 0.9 give a positive result
skp neg,ENDSWITCH ;if negative then jump to ENDSWITCH
ldax db ;read db
sof 1,-0.9 ;deduct 0.9
skp neg,LO ;if negative jump to LO, output of debounce is low
sof 0,0.999 ;else output of debounce is high
wrax mom,0 ;set mom to 1 (high)
skp zro,ENDSWITCH ;jump to ENDSWITCH
LO:
ldax mom ;read mom
skp neg,ENDSWITCH ;if it's negative then debounce was already low last time so do nothing, jump to ENDSWITCH
sof 0,-0.999 ;else mom was high last time so switch has only just been pressed (falling edge)
wrax mom,0 ;set mom to -1 (low)
ldax latch ;read latch
sof -1,0 ;invert, high becomes low, low becomes high
wrax latch,0 ;write to value to latch
ENDSWITCH:
;tap tempo, uses rmp0 as a 1 Hz rising ramp, runs whilst latch is low and is sampled and held when latch is high
ldax latch ;read latch
skp neg,LOW ;if negative jump to LOW
jam rmp0 ;else latch is high, jam rmp0 (reset to 0)
ldax ramp ;read ramp, will contain last value of rmp0 before latch went high
wrax taptempo,0 ;write to taptempo
skp zro,ENDTT ;jump to ENDTT
LOW:
sof 0,0.064
wrax rmp0_rate,0 ;set rmp0 rate to 1Hz
cho rdal,rmp0 ;read value of rmp0
sof -2,0.999
sof 1,0.001 ;level shift to 0 to 1 rising ramp
wrax ramp,1 ;write to ramp
sof 1,-0.999 ;deduct 0.999 from ramp
skp neg,ENDTT ;if answer is positive then second tap hasn't happened with 0.999 ms of first
ldax taptempo ;so keep last value of taptempo
wrax ramp,0
sof 0,0.999 ;and reset latch high
wrax latch,0
ENDTT:
;Taptempo rate indicator, creates a square wave at the tap tempo rate
sof 0,0.064
wrax rmp1_rate,0 ;set rmp1 rate to 1Hz
cho rdal,rmp1 ;read value of rmp1
sof -2,0.999 ;level shift to 0 - 1 rising ramp
sof 1,0.001
rdax taptempo,-0.5 ;deduct half of the taptempo value
skp neg,ENDLED ;if negative skip to ENDLED
jam rmp1 ;else reset ramp1
ldax led ;and invert value of led register, creates square wave at taptempo rate
sof -1,0
wrax led,0
ENDLED:
;Tremolo
;clear registers and initialize LFOs:
skp run,endclr
wlds sin0,12,100
wlds sin1,0,16383 ;initialize LFO1 SIN F=0, A=16383
endclr:
;sum inputs to mono:
rdax adcl,0.5 ;read from ADC left and divide by 2
rdax adcr,0.5 ;read from ADC right and divide by 2
wrax mono,0.5 ;write result to MONO and divide by 2
;Do tremelo, start with controlling LFO Sin1 with pot1:
ldax taptempo ;get control pot
mulx taptempo ;square function
sof 0.4,0.1 ;scale rate to reasonable range
wrax sin1_rate,0 ;write to sin1 rate register
cho rdal,sin1 ;get sinewave, +/-0.5
sof 1,0.5 ;add 1/2 to get sinwave that swings 0 to 1
wrax trem,0 ;write tremelo modulation signal
;now produce output:
rdax mono,0.5 ;attenuate signals so as not to clip
mulx trem ;ACC=mono*trem
sof 1.999,0 ;boost tremelo to maintain average amplitude
rdax mono,-0.5 ;ACC=ACC+mono*-0,5
mulx pot1 ;crossover between input and tremelo with pot1
rdax mono,0.5 ;ACC=ACC+mono*0,5
sof 1.999,0 ;recover gain
sof 1,0.2 ;ACC=ACC+0,2
wrax dacl,0 ;ACC->DACL
ldax led ;read led register
wrax dacr,0 ;write to DACR, flashes LED attached to DACR
