DHT22.txt

\ *********************************************************************
\ DHT11, DHT22 1-wire Control
\    Filename:      DHT22.txt
\    Date:          28 july 2022
\    Updated:       28 july 2022
\    File Version:  0.0
\    MCU:           ESP32-WROOM-32
\    Forth:         ESP32forth all versions 7.x++
\    Copyright:     ohiyooo2 / Frank Lin
\    Original publ. https://ohiyooo2.pixnet.net/blog/post/406078286
\    Adaptation for GitHub: Marc PETREMANN
\    GNU General Public License
\ *********************************************************************


\
\  DHT11, DHT22 1-wire Control Code - ESP32FORTH
\     Frank Lin 2022.7.20
\

\
\   Digital I/O Access Codes
\


: >OUTPUT ( pin --)      \ set the direction of digital I/O to output
    output pinMode
;

: <INPUT  ( pin --)      \ set the direction of digital I/O to input
    input pinMode
;

: PULLUP ; immediate     \ dummy for syntax sweeter

: ->High ( pin --)       \ put digital I/O to High
   high digitalWrite
;

: ->Low  ( pin --)       \ put digital I/O to Low
   low digitalWrite
;

: Pin@ ( pin -- status)   \ read the state of digital I/O, 0=low, 1=high
   digitalRead
;

: ticks ( -- ticks)
   ms-ticks
;


\
\  extension for ESP32FORTH
\    ESP32FORTH only has catch/throw, no standard ABORT, ABORT"
\


: abort ( --)  -1 throw ;

: abort" ( flag "text" --)
   state @
   if
      postpone if   postpone s"   postpone type   postpone cr
                    postpone abort
      postpone then
   else [char] " parse type cr abort then
; immediate




\
\  DHT Sensor, 1-wire data Pin
\


14 constant DHTPin           \ Pin14 as DHT data Pin

: delay  ( n--) for next ;   \ used as the delay timer

\ DIO and delay speed test
\

: t1 ticks DHTPin 1000000 for DHTPin Pin@ 0= if then next drop ticks swap - . ;

\
\ result: 642 ms / 1000000 = 0.642 uS per loop
\

: t2 ticks 1000000 delay ticks swap - . ;

\
\  result: 96.5 ms / 1000000 = 0.0965 uS for 1 delay
\

: wait (  --)     \ wait until pulse-high
   begin DHTPin Pin@ until
;

\
\ DHT 1-wire signal:
\   start: 50uS Low
\   signal 1:      70 uS Pulse High
\   signal 0: 26 - 28 uS Pulse High


\
\     112uS / 0.642uS = 174
\  67.175uS / 0.642uS = 104
\


: signal@  ( --  true=1/false=0)
   174  ( ~112uS)
   for
       DHTPin Pin@ 0=  ( pulse low?)
       if  r> 104 ( ~ 67.175uS) <  exit  ( length > 70 = 44.825 uS)
       then
   next
   ." Error! Signal not match with expectation!" cr
   abort
;


: 8bits@ ( --  Data)
   0  ( data)
   7 for
        wait
        signal@ if 1 r@ lshift or then
     next
;

: 40bits@ ( -- n1 n2 n3 n4 n5)
  4 for 8bits@ next
;

\
\  Start Signal
\   18mS Low, to active communication
\   then 20 - 40uS High
\   then wait DHT sends 80uS Low, 80uS High
\   then receive 40bits data transmition from DHT
\

\
\ 20uS = 20/0.0965 ~ 207 delay
\ 82uS = 82/0.0965 ~ 850 delay
\ 14uS = 14/0.0965 ~ 145 delay
\

: start! ( --)
   DHTPin >OUTPUT
   DHTPin ->Low
     20 ms
   DHTPin ->High
     145 delay  ( ~ 14uS)
   DHTPin <INPUT

;

: DHT@ ( -- n1 n2 n3 n4 CheckSum)
   start!
   207 delay ( ~ 20uS)
   wait
   850 delay ( ~ 82uS)
   40bits@
;


: >DHT11 ( RHint RHdec Tint Tdec Checksum -- RH Temp)
   nip  over -  >r    ( RHint RHdec Tint | R: checksum')
   nip  over r>    -
   abort" Error: CheckSum not match!!"
;


: ?negate ( n1 n2 -- n3)
    $80 and if negate then
;


: >DHT22 ( RH.H RH.L T.H T.L Checksum -- RH Temp)
   >r   2dup + >r
   swap 8 lshift or  >r  ( RH.H RH.L R: T CS1 CS)
   2dup + >r             ( RH.H RH.L R: CS2 T CS1 CS)
   swap 8 lshift or      ( RH R: CS2 T CS1 CS)
   r> r> swap            ( RH T CS2 R: CS1 CS)
   r> +                  ( RH T CS3 R: CS)
   256 u/mod drop
   r> <>
   abort" Error: CheckSum not match!!"

   $7fff over and  swap ?negate
;

: DHT11@ ( -- RH T)
    DHT@  >DHT11
    10 * >r  10 * r>
;

: DHT22@ ( -- RH T)
    DHT@  >DHT22
;


: .[xx.x]  dup <# # [char] . hold #s swap sign #> type ;


: DHT11
   cr
   begin
     DHT11@
     ." Temperature = "       .[xx.x] ." C , "
     ." Relative Humidity = " .[xx.x] ." %"    cr
     2000 ms
   again
;


: DHT22
   cr
   begin
     DHT22@
     ." Temperature = "       .[xx.x] ." C , "
     ." Relative Humidity = " .[xx.x] ." %"    cr
     2000 ms
   again
;