# Arduino Analog¶

Accessing the Analog ports for reading needs the files lib/bitnames.frt for basic routines, the file appl/arduino/blocks/ports-arduinotype.frt for the actual ports and appl/arduino/blocks/wiring_analog.frt for the code to do the work. After loading the files, the Analog Conversion Module has to be initialized with the adc.init. This has to be done after a reset and power cycle as well.

Now it is time to connect some hardware to one of the ports labled Analog In. Once this is done, some simple commands will work:

> analog.1 adc.get u.
67 ok
>


The ADC on the ATmega has a resolution of 10 bits, thus a number between 0 and 1023 can be expected as the result.

Note that the ADC module needs some time between two conversion. If you do it too fast, expect malfunctions or even crashes. A simple 50 ms circumvent most problems.

\ continuously read the adc port
\ and print the new value if it
\ has changed considerably since last round
\ note the 50ms delay to keep things
\ run smoothly. A key press will
: analog-test
0
begin
( -- old )
analog.1 adc.get ( -- old new  )
swap over        ( -- new old new )
- abs 6 >        ( -- new f )
50 ms            ( wait...)
if dup u. then   ( -- new )
key?             ( -- new f )
until
key drop
drop ;