anchor.diff:  
   \ Checks I2C1 busy bit
   : i2c-busy?   ( -- b) I2C1-SR2 h@ 1 bit and 0<> ;
  -
   
   \ Init and reset I2C. Probably overkill. TODO simplify
   : i2c-init
  
positive.code:       then
      loop
    16 +loop ;
  
  
  
negative.code:   \ AHBCLK / APB1 = 36MHz
    \ AHBCLK / APB2 = 72MHz
    \ I2C = APB1 = 36MHz
  
    \ Configure clock control registers?!
  
    27           \ CCR 27?
    15 bit or    \ FM
    I2C1-CCR h!  \ FREQ = 36MHZ, 31 ns; DUTY=0 3x 31ns = 10 MHz; must divide by 27
    3  I2C1-TRISE h!         \ 2+1 for 1000ns SCL
  
    0  bit I2C1-CR1 hbis!    \ Enable bit
  