anchor.diff:          i2c-EV6                  \ wait for ADDR and clear
           i2c-ACK-0
           i2c-SR1-BTF i2c-SR1-wait \ wait for BTF
  +        i2c-nak?
           i2c-stop!                \ set stop without waiting
           0 i2c.needstop !
         endof
  
positive.code:   i2c-EV6a                       \ wait for completion of addressing or AF
  ;
  
  : i2c-xfer ( u -- nak) \ prepares for an nbyte reply. Use after i2c-addr. Stops i2c after completion.
    dup i2c.cnt !
    i2c-EV6b
      case
  
negative.code:         i2c-DR!
          i2c-EV6    \ wait until ready to read
          \ i2c-SR1-ADDR i2c-SR1-wait
          i2c-nak?
          1 i2c.needstop !
      endcase
  ;
  