' This program uses the Propeller Demo Board, Rev C
' The microphone is digitized and the samples are played on the headphones.

CON  
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000 
' At 80MHz the ADC/DAC sample resolutions and rates are as follows: 
' sample   sample               
' bits       rate               
' ----------------              
' 5       2.5 MHz               
' 6      1.25 MHz               
' 7       625 KHz               
' 8       313 KHz               
' 9       156 KHz               
' 10       78 KHz               
' 11       39 KHz               
' 12     19.5 KHz               
' 13     9.77 KHz               
' 14     4.88 KHz              
  bits = 8               'try different values from table here 
PUB go
  cognew(@asm_entry, 0)   'launch assembly program into a COG 
DAT  
              org  
asm_entry     mov       dira,asm_dira                   'make pins 8 (ADC) and 0 (DAC) outputs

              movs      ctra,#8                         'POS W/FEEDBACK mode for CTRA
              movd      ctra,#9
              movi      ctra,#%01001_000
              mov       frqa,#1

              movs      ctrb,#10                        'DUTY DIFFERENTIAL mode for CTRB
              movd      ctrb,#11
              movi      ctrb,#%00111_000
              
              mov       asm_cnt,cnt                     'prepare for WAITCNT loop
              add       asm_cnt,asm_cycles 
:loop         waitcnt   asm_cnt,asm_cycles              'wait for next CNT value (timing is determinant after WAITCNT)
              mov       asm_sample,phsa                 'capture PHSA and get difference
              sub       asm_sample,asm_old
              add       asm_old,asm_sample
              wrlong    asm_sample,dadd              
              shl       asm_sample,#32-bits             'justify sample and output to FRQB
              mov       frqb,asm_sample
              jmp       #:loop   'wait for next sample period 
asm_cycles    long      |< bits - 1                     'sample time
asm_dira      long      $00000E00                       'output mask
dadd          long      $7ee0
asm_cnt       res       1
asm_old       res       1
asm_sample    res       1